# AC 90-114C: Automatic Dependent Surveillance-Broadcast Operations - Type: Advisory circular (guidance, not mandatory unless a rule or AD requires it) - Status: Current - Approved: January 14, 2025 - Last reviewed: January 16, 2025 - Family: AC 90-114 - Cancels: [AC 90-114B CHG 1](https://openairdocs.org/ac/90-114B-CHG-1) - 14 CFR parts: 91 - 14 CFR sections: [91.225](https://www.ecfr.gov/current/title-14/section-91.225), [91.227](https://www.ecfr.gov/current/title-14/section-91.227) - Pages: 84 - PDF: https://openairdocs.org/files/sha256/11/a3/11a3d7fc1f9ef4acf091bffae1ae9d5eaee388b5b11271a721a09c195146e590 - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/DRSDOCID128021846820250116135325.0001 - DRS record last changed: November 21, 2025 - Page: https://openairdocs.org/ac/90-114 ## Versions - [AC 90-114C](https://openairdocs.org/ac/90-114) (Current), approved Jan 14, 2025, 84 pages - [AC 90-114B CHG 1](https://openairdocs.org/ac/90-114B-CHG-1) (Historical), approved Dec 15, 2022, 74 pages. Change 1 of AC 90-114B. - [AC 90-114B](https://openairdocs.org/ac/90-114B) (Historical), approved Dec 30, 2019, 59 pages - [AC 90-114A CHG 1](https://openairdocs.org/ac/90-114A-CHG-1) (Historical), approved Mar 7, 2016, 53 pages. Change 1 of AC 90-114A. - [AC 90-114A](https://openairdocs.org/ac/90-114A) (Historical), approved Oct 28, 2014, 47 pages - [AC 90-114 CHG 1](https://openairdocs.org/ac/90-114-CHG-1) (Historical), approved Sep 21, 2012, 43 pages. Change 1 of AC 90-114. - [AC 90-114](https://openairdocs.org/ac/90-114?v=DRSDOCID156248070120240729173820) (Historical), approved Dec 8, 2011, 29 pages ## Text Each page's text from the PDF; open the PDF at a page with #page=N. ### Page 1 U. S. Department of Transportation Federal Aviation Administration Advisory Circular Subject: Automatic Dependent Surveillance-Broadcast Operations Date: 1/14/25 AC No: 90-114C Initiated by: AFS-400 Change: In May 2010, the Federal Aviation Administration (FAA) issued Title 14 of the Code of Federal Regulations (14 CFR) §§ 91.225 and 91.227. This rule requires Automatic Dependent Surveillance-Broadcast (ADS-B) Out performance when operating in designated classes of airspace within the U.S. National Airspace System (NAS) after January 1, 2020, unless authorized by air traffic control (ATC). This advisory circular (AC) provides users of the NAS guidance regarding how to conduct operations in accordance with 14 CFR §§ 91.225 and 91.227. The appendices in this AC provide guidance for additional operations enabled by ADS-B, including ADS-B In. The contents of this document do not have the force and effect of law and are not meant to bind the public in any way, and the document is intended only to provide information to the public regarding existing requirements under the law or agency policies. Hugh J . Thomas for Robert M. Ruiz Acting Executive Director, Flight Standards Service ### Page 2 ii CONTENTS Paragraph Page Chapter 1. Automatic Dependent Surveillance-Broadcast Operations … 1-1 1.1 Purpose of This Advisory Circular (AC) … 1-1 1.2 Audience … 1-1 1.3 Where You Can Find This AC … 1-1 1.4 What This AC Cancels … 1-1 1.5 Scope … 1-1 1.6 AC Feedback Form … 1-2 Chapter 2. Overview and S ystem Description … 2-1 2.1 Overview … 2-1 2.2 ADS-B System Description … 2-1 2.3 ADS-B Broadcast Services … 2-2 2.4 Use of ADS-B In Information for Traffic Situational Awareness … 2-2 Chapter 3. Operational Considerations … 3-1 3.1 U.S. ADS-B Airspace and Equipment Performance Requirements … 3-1 3.2 Exceptions to Airspace Requirements … 3-3 3.3 Traffic Awareness Beacon System (TABS) … 3-3 Chapter 4. Operating Procedures … 4-1 4.1 General Operating Procedures … 4-1 4.2 Operator Familiarity of the Installed ADS-B System … 4-1 4.3 ADS-B Equipment Operations (U.S. Airspace) … 4-1 4.4 Flight Plans (FP) … 4-9 4.5 Preflight Requirements (U.S. Airspace) … 4-12 4.6 Flightcrew Entry of Required ADS-B Data … 4-15 Appendix A. ADS-B In-T rail Procedure … A-1 Appendix B. CAVS Us ing ADS-B In … B-1 Appendix C. ADS-B I n Operations—Aircraft Qualification and Maintenance … C-1 Appendix D. De finitions … D-1 Appendix E. Rel ated Regulations and Reading Material … E-1 Appendix F. In terval Management … F-1 Appendix G. CDTI Assisted Separation On Approach … G-1 ### Page 3 iii List of Figures Figure 3-1. Automatic Dependent Surveillance-Broadcast Airspace Rule (14 CFR § 91.225) Diagram … 3-2 Figure A-1. R eduction of Aircraft Separation Minima With In-Trail Procedure … A-1 Figure A-2. In-T rail Procedure Distances Illustrated … A-3 Figure A-3. S imilar Track … A-4 Figure A-4. In-T rail Procedure Climb/Descent Variations … A-7 Figure F-1. M aintain Current Spacing … F-7 Figure F-2. C apture Then Maintain … F-7 Figure F-3. A chieve-by Then Maintain (Cross) … F-8 Figure F-4. F inal Approach Spacing … F-8 Figure G-1. C ontroller Identifies CAS-A TTF Aircraft … G-5 Figure G-2. C ontroller Issues Instruction to Follow the Designated Traffic Along With Approach Clearance … G-6 L ist of Tables Table 4-1. Aircraft Identification Transmission Examples … 4-17 Table A-1. In-T rail Procedure Initiation/Maneuver Criteria (Reference RTCA DO-312 Supplement) … A-12 Table A-2. F lightcrew Standardized Free Text Controller-Pilot Data Link Communication Message Set for In-Trail Procedure … A-13 Table A-3. C ontroller Free Text Controller-Pilot Data Link Communication Message Set for In-Trail Procedure … A-14 Table F-1. C learance Element Formats … F-6 Table F-2. I nterval Management Clearance Types Summarized … F-9 ### Page 4 **1-1 CHAPTER 1. AUTOMATIC DEPENDENT SURVEILLANCE-BROADCAST** **OPERATIONS** 1.1 Purpose of This Advisory Circular (AC). The intent of this AC is to facilitate operations using Automatic Dependent Surveillance-Broadcast (ADS-B) technology in compliance with Title 14 of the Code of Federal Regulations (14 CFR) §§ 91.225 and 91.227. The appendices provide guidance on additional ADS-B Out and ADS-B In operations that may be authorized by the Administrator. The contents of this document do not have the force and effect of law and are not meant to bind the public in any way, and the document is intended only to provide information to the public regarding existing requirements under the law or agency policies. 1.2 Audience. This AC applies to all operators intending to use ADS-B within the U.S. National Airspace System (NAS). 1.3 Where You Can Find This AC. You can find this AC on the Federal Aviation Administration’s (FAA) website at https://www.faa.gov/regulations_policies/advisory_cir culars and the Dynamic Regulatory System (DRS) at https://drs.faa.gov. 1.4 What This AC Cancels. AC 90-114B, Automatic Dependent Surveillance-Broadcast Operations, dated December 30, 2019, is canceled. 1.5 Scope. This AC contains an overview of the ADS-B system and general operating procedures in compliance with the airspace and performance requirements of 14 CFR §§ 91.225 and 91.227. The appendices provide guidance on additional ADS-B Out and ADS-B In operations that may be authorized by the Administrator. 1.5.1 Obligation. The contents of this document do not have the force and effect of law and are not meant to bind the public in any way. This document is intended only to provide clarity to the public regarding existing requirements under the law or agency policies. This AC is not mandatory and does not constitute a regulation. The guidance contained herein is not legally binding in its own right and will not be relied upon by the FAA as a separate basis for affirmative enforcement action or other administrative penalty. Conformity with the guidance document is voluntary only, and nonconformity will not affect rights and obligations under existing statutes and regulations. This AC describes an acceptable means, but not the only means, to meet the requirements of 14 CFR. 1.5.2 Authorization to Conduct ADS-B Out Operations. The FAA does not require an authorization to conduct ADS-B Out operations in the airspace specified in 14 CFR § 91.225 (U.S. airspace). However, pilots, dispatch personnel, and maintenance personnel should be familiar with the information provided in this AC. 1.5.3 Certification and Installation of ADS-B Out Equipment. AC 20-165, Airworthiness Approval of Automatic Dependent Surveillance - Broadcast OUT Systems, contains guidance associated with the installation and airworthiness approval of ADS-B Out equipment. ### Page 5 1-2 Note: Outside the U.S. NAS, many worldwide Air Traffic Service Providers (ATSP) allow the use of ADS-B equipment certified to the European Union Aviation Safety Agency (EASA) Acceptable Means of Compliance (AMC) 20-24, Certification Considerations for the Enhanced ATS in Non-Radar Areas Using ADS-B Surveillance (ADS-B-NRA) Application via 1090 MHz Extended Squitter. EASA AMC 20-24 is intended for Non-Radar Areas (NRA). However, AMC 20-24 equipment does not necessarily comply with 14 CFR § 91.225. 1.6 AC Feedback Form. For your convenience, the AC Feedback Form is the last page of this AC. Note any deficiencies found, clarifications needed, or suggested improvements regarding the contents of this AC on the Feedback Form. ### Page 6 **2-1 CHAPTER 2. OVERVIEW AND SYSTEM DESCRIPTION** 2.1 Overview. Starting with the National Airspace System (NAS)-wide implementation of ADS-B, the FAA has begun to facilitate improvements needed to increase the capacity and efficiency of the NAS while maintaining safety. ADS-B supports these improvements by providing a higher update rate and enhanced accuracy of surveillance information over the current radar-based surveillance systems. In addition, ADS-B enables the expansion of air traffic control (ATC) surveillance services into areas where none existed previously. The ADS-B ground system also provides Traffic Information Service-Broadcast (TIS-B) and Flight Information Service-Broadcast (FIS-B) for use on appropriately equipped aircraft, enhancing the user’s situational awareness and improving the overall safety of the NAS. 2.2 ADS-B System Description. 2.2.1 ADS-B System Architecture. The ADS-B system architecture is composed of aircraft avionics and an Air Traffic Service Provider (ATSP) infrastructure. Onboard “position source” avionics determine the position of the aircraft, typically by using the Global Navigation Satellite Systems (GNSS) and transmitting this and additional information about the aircraft to receiver stations for use by ATC, to ADS-B In-equipped aircraft, and to other aviation service providers. 2.2.2 ADS-B Operating Frequencies. In the United States, the ADS-B system operates on two frequencies: 1090 or 978 megahertz (MHz). See Chapter 3, Figure 3-1, Automatic Dependent Surveillance-Broadcast Airspace Rule (14 CFR § 91.225) Diagram, for airspace and frequency requirements. 2.2.2.1 The 1090 MHz Frequency. The 1090 MHz frequency is associated with current Mode A, C, and S transponder operations. ADS-B information is included in Mode S transponders’ Extended Squitter (ES) transmit messages, and referred to as 1090ES in this AC. 2.2.2.2 The 978 MHz Frequency. ADS-B equipment operating on 978 MHz are referred to as Universal Access Transceivers (UAT) in this AC. 2.2.3 ADS-B Avionics Operating Modes. ADS-B avionics can have the ability to both transmit and receive information. 2.2.3.1 ADS-B Out. The transmission of ADS-B information from aircraft is known as ADS-B Out. 2.2.3.2 ADS-B In. The receipt of ADS-B information by an aircraft is known as ADS-B In. Note: Since January 1, 2020, all aircraft operating within the airspace defined in 14 CFR § 91.225 are required to transmit the information defined in 14 CFR § 91.227. Refer to 14 CFR §§ 91.225 and 91.227 for more detailed information. ### Page 7 2-2 2.3 ADS-B Broadcast Services. In the United States, ADS-B implementation includes four broadcast services: Automatic Dependent Surveillance-Rebroadcast (ADS-R), ADS-R Same Link Rebroadcast (ADS-R-SLR), TIS-B, and FIS-B. For a detailed explanation of these services, refer to the FAA Surveillance and Broadcast Services Description Document (SRT-047). 2.3.1 ADS-R. Because the ADS-B system operates on two separate frequencies (1090 MHz and 978 MHz), there is a need to translate, reformat, and rebroadcast the information from each frequency to enable aircraft receiving on the other frequency to process and use the other’s information. This process is referred to as ADS-R and occurs within an ADS-B ground station. An aircraft or vehicle that is ADS-B Out and is receiving ADS-R service is known as an ADS-R client. An ADS-B-equipped aircraft or vehicle on the opposite link of the ADS-R client that has its messages translated and transmitted by the ground system is known as an ADS-R target. See paragraph 2.3.5 for ADS-R client qualification criteria. Note: Aircraft operating on the same ADS-B frequency exchange information directly and do not require ADS-R translation. Aircraft with ADS-B In capability on both UAT and 1090ES do not require ADS-R service. 2.3.2 TIS-B. TIS-B is the broadcast of transponder-based Mode C or Mode S traffic information derived from ATC surveillance systems. TIS-B provides ADS-B In-equipped aircraft with a more complete picture of surrounding traffic in situations where not all aircraft are equipped with ADS-B. An aircraft or vehicle that is ADS-B Out and is receiving TIS-B service is known as a TIS-B client. A non-ADS-B-equipped aircraft or vehicle that has its position transmitted in TIS-B reports is known as a TIS-B target. See paragraph 2.3.5 for TIS-B client qualification criteria. 2.3.3 FIS-B. FIS-B operates on UAT only and provides ADS-B In-equipped aircraft with a suite of advisory-only aeronautical and weather information products to enhance the user’s situational awareness. Additional information on FIS-B and the products available through the service are provided in the Aeronautical Information Manual (AIM) and AC 00-63, Use of Flight Deck Displays of Digital Weather and Aeronautical Information. 2.3.4 ADS-R SLR. ADS-R SLR uses ADS-R to rebroadcast ADS-B messages sent by aircraft on or near a runway; it is available at all airports with an FAA surface surveillance system. Airport structures can block reception of direct aircraft-to-aircraft ADS-B messages on an airport surface, impacting use of ADS-B In systems on an airport surface. This effect is mitigated by ADS-R SLR. 2.3.5 ADS-B Out Requirements for ADS-R and TIS-B. The FAA provides ADS-R and TIS-B services for equipment that meets performance requirements outlined in 14 CFR § 91.227 or complies with requirements specified in Technical Standard Order (TSO)-C199, Traffic Awareness Beacon System (TABS). 2.4 Use of ADS-B In Information for Traffic Situational Awareness. This paragraph provides guidance on the use of ADS-B In information for traffic situational awareness. ### Page 8 2-3 See the appropriate appendices of this AC for guidance on the use of ADS-B In for the more advanced procedures, which may be performed if authorized. There is no specific authorization to use ADS-B In for traffic situational awareness. Installation of ADS-B In equipment is not required for compliance with 14 CFR § 91.225 or § 91.227. However, aircraft owners and operators who choose to voluntarily equip with ADS-B In avionics will achieve greater benefit from the technology through improved traffic situational awareness on the ground and in the air. Note: This AC only addresses ADS-B In systems installed consistent with AC 20-172, Airworthiness Approval for ADS-B In Systems and Applications, and meeting TSO-C195b, Avionics Supporting Automatic Dependent Surveillance – Broadcast (ADS-B) Aircraft Surveillance Applications (ASA), or later revision. 2.4.1 ADS-B In Systems. Most ADS-B In systems will include a flight deck traffic display depicting the relative position and related information of ADS-B-equipped aircraft presented on a plan view. This traffic display is only one component of the input and output devices collectively known as a Cockpit Display of Traffic Information (CDTI). The traffic display may be on a dedicated display or integrated into and presented on an existing display (e.g., navigation display (ND) or multifunction display (MFD)). The terms traffic display and CDTI are used interchangeably when the meaning is clear in context. In many installations, a moving map depicting key surface elements of the airport may be displayed when on the ground or within a predefined altitude/distance from an airport while airborne. Note: ADS-B Traffic Advisory System (ATAS) is an ADS-B In application intended specifically for General Aviation (GA) use that incorporates an audio traffic alerting capability. 2.4.2 Operation. The CDTI will display nearby ADS-B Out traffic and may also display TIS-B traffic and FIS-B information if UAT is equipped, depending on the installation and operating airspace. The display may have functionality to allow the pilot to select a target to obtain additional information that might not be automatically displayed, such as distance from own-ship and groundspeed (GS). The system will also provide range selection and declutter functionality. More advanced ADS-B In systems may also include certified functionality to perform ADS-B In procedures described in the appendices of this AC. Note: For traffic situational awareness, pilots are encouraged to incorporate the display in their normal scan to aid in the early detection of nearby traffic when in visual conditions and to aid in understanding the flow and amount of nearby traffic when in instrument conditions. However, the traffic display is not intended to be used for self-separation or to deviate from an ATC clearance. Should questions arise about a potential conflict with traffic while on an instrument flight rules (IFR) clearance, the pilot should query ATC. Pilots are also cautioned to not allow the display to become a distraction from the primary task of flying the aircraft or scanning outside for traffic. Finally, pilots are cautioned against ### Page 9 2-4 unnecessarily communicating on the ATC frequency about traffic observed on the traffic display. 2.4.3 Limitations. Pilots should understand the proper use and limitations of their equipment and should adhere to the following: 2.4.3.1 Only use the traffic display to supplement what can be seen out the window (OTW), except when authorized to conduct ADS-B In operations described in the appendices of this AC. Pilots must always conduct OTW scans to see and avoid as required under 14 CFR § 91.113(b). 2.4.3.2 Unless specifically certified for the function, the traffic display is not intended for collision avoidance or self-separation. 2.4.3.3 Not all ground and airborne traffic will appear on the traffic display. The traffic display can only display properly equipped ADS-B Out traffic broadcasting on the received frequencies, and, depending on the operating location, ADS-R SLR, ADS-R, TIS-B, and/or Airborne Collision Avoidance System (ACAS) (if installed) traffic. Additionally, the completeness of the traffic situational awareness information is affected by range, signal quality, and proper installation and function of the ADS-B Out system on the traffic aircraft. 2.4.3.4 Unless initiated by the controller, pilots should typically not use the call sign or Aircraft Identification (ACID) of observed traffic in radio communications, as this could create confusion for both ATC and pilots monitoring the frequency. 2.4.3.5 In multipiloted aircraft, establish and comply with crew coordination procedures on the use of the CDTI and ADS-B In information to minimize heads-down time. 2.4.3.6 Use of the traffic display does not change pilot or controller responsibilities. 2.4.3.7 If at any time the presented information becomes unreliable, inoperative, or a distraction, disregard the information presented on the traffic display. 2.4.3.8 In ACAS-equipped aircraft, ADS-B In traffic display information does not change existing procedures for response to a traffic advisory (TA) and/or Resolution Advisory (RA). ### Page 10 **3-1 CHAPTER 3. OPERATIONAL CONSIDERATIONS** 3.1 U.S. ADS-B Airspace and Equipment Performance Requirements. Since January 1, 2020, unless authorized by air traffic control (ATC), all aircraft operating in the airspace specified in 14 CFR § 91.225 must meet the equipment performance requirements defined in 14 CFR § 91.227. This chapter describes both the airspace and equipment performance requirements of 14 CFR §§ 91.225 and 91.227. Operators should consider the need to access ADS-B-required airspace and the performance requirements of that airspace when equipping for compliance with 14 CFR §§ 91.225 and 91.227. 3.1.1 Inside Class A Airspace. Operations in Class A airspace must: 1. Meet the equipment performance requirements in: a. Technical Standard Order (TSO)-C166b, Extended Squitter Automatic Dependent Surveillance - Broadcast (ADS-B) and Traffic Information Service - Broadcast (TIS-B) Equipment Operating on the Radio Frequency of 1090 Megahertz (MHz) (1090ES), and Section 2 of RTCA DO-260B, Minimum Operational Performance Standards for 1090 MHz Extended Squitter Automatic Dependent Surveillance - Broadcast (ADS-B) and Traffic Information Services - Broadcast (TIS-B) (as referenced in TSO-C166b); or b. TSO-C166c and Section 2 of RTCA DO-260C as modified by RTCA DO-260C Change 1 (as referenced in TSO-C166c). 2. Meet the requirements of 14 CFR § 91.227. Note: Although TSO-C166b and later revisions incorporate standards for TIS-B equipment, TIS-B equipage (ADS-B In) is not required for compliance with 14 CFR §§ 91.225 and 91.227. 3.1.2 Outside Class A Airspace. Operations within airspace defined in 14 CFR § 91.225, but outside Class A airspace must: 1. Meet the requirements of 14 CFR § 91.227; and 2. Meet the performance requirements in: a. TSO-C166b and Section 2 of RTCA DO-260B (as referenced in TSO-C166b); b. TSO-C166c and Section 2 of RTCA DO-260C as modified by RTCA DO-260C Change 1 (as referenced in TSO-C166c); c. TSO-C154c, Universal Access Transceiver (UAT) Automatic Dependent Surveillance-Broadcast (ADS-B) Equipment Operating on Frequency of 978 MHz, and Section 2 of RTCA DO-282B, Minimum Operational Performance Standards for Universal Access Transceiver (UAT) Automatic Dependent Surveillance - Broadcast (ADS-B) (as referenced in TSO-C154c); or d. TSO-C154d and Section 2 of RTCA DO-282C (as referenced in TSO-C154d). ### Page 11 3-2 3.1.3 Operation of Aircraft With Dual ADS-B Out Links. Operators of aircraft equipped with both 1090 Extended Squitter (ES) and UAT ADS-B systems should be aware that broadcasting only on 978 MHz (UAT) in Class A airspace is not sufficient to meet the requirements of 14 CFR § 91.225. Before operating in Class A airspace, operators of such aircraft should verify that their 1090ES equipment is broadcasting properly. 3.1.4 Operation of Unmanned Aircraft. For unmanned aircraft: 1. No person may operate an unmanned aircraft under a flight plan (FP) and in two-way communication with ATC unless: a. That aircraft has equipment installed that meets the performance requirements in TSO-C166b (including Section 2 of RTCA DO-260B, as referenced in TSO-C166b), TSO-C166c (including Section 2 of RTCA DO-260C as modified by RTCA DO-260C Change 1, as referenced in TSO-C166c), TSO-C154c (including Section 2 of RTCA DO-282B, as referenced in TSO-C154c), or TSO-C154d (including Section 2 of RTCA DO-282C, as referenced in TSO-C154d); and b. The equipment meets the requirements of 14 CFR § 91.227. 2. No person may operate an unmanned aircraft under 14 CFR part 91 with ADS-B Out equipment in transmit mode unless: a. The operation is conducted under an FP, and the person operating that unmanned aircraft maintains two-way communication with ATC; or b. The use of ADS-B Out is otherwise authorized by the Administrator. Figure 3-1. Automatic Dependent Surveillance-Broadcast Airspace Rule (14 CFR § 91.225) Diagram ### Page 12 3-3 3.2 Exceptions to Airspace Requirements. The requirements of 14 CFR § 91.225(b) do not apply to any aircraft that was not originally certified with an engine-driven electrical system or that has not subsequently been certified with such a system installed, including balloons and gliders. The FAA has previously determined that the same aircraft excluded from the transponder requirement are excluded from the ADS-B Out equipage. Accordingly, an aircraft that subsequently has been installed with batteries or an electric starter would not be required to equip for ADS-B Out. These aircraft may conduct operations without ADS-B Out in the airspace specified in 14 CFR § 91.225(d)(2) and (4). However, for other aircraft without ADS-B Out, 14 CFR § 91.225(g) requires ATC authorization prior to operation in ADS-B Out-required airspace. 3.3 Traffic Awareness Beacon System (TABS). Operators of aircraft exempt from carrying a transponder or ADS-B equipment may wish to consider installing a TABS transponder or a transponder with a TABS-compliant position source (refer to TSO-C199, Traffic Awareness Beacon System (TABS)). TABS transponders do not meet the transponder requirements defined in 14 CFR § 91.215, and TABS-compliant position sources do not meet the requirements defined in 14 CFR § 91.227. However, they will allow TABS-equipped aircraft to be electronically “visible” to aircraft equipped with Airborne Collision Avoidance Systems (ACAS), traffic advisory systems (TAS), and ADS-B In systems. TABS-equipped aircraft that are broadcasting an ADS-B In capability will also become TIS-B clients. ### Page 13 **4-1 CHAPTER 4. OPERATING PROCEDURES** 4.1 General Operating Procedures. This chapter describes the general procedures for ADS-B Out operations in accordance with 14 CFR §§ 91.225 and 91.227. All operators should use this information when planning and conducting operations requiring ADS-B Out performance. 4.2 Operator Familiarity of the Installed ADS-B System. 4.2.1 System Operation Familiarity. All operators should use the applicable Airplane Flight Manual (AFM), Aircraft/Airplane Flight Manual Supplement (AFMS), Rotorcraft Flight Manual (RFM), Rotorcraft Flight Manual Supplement (RFMS), pilot’s operating handbook (POH), or other required operating handbooks or manuals to become familiar with the proper operation of the installed ADS-B system and any procedures expected of the user for indications of reduced performance or failures within the system. 4.2.2 Understanding Failure Indicators Within the System. Because many ADS-B system installations are upgrades of transponders (Mode S), there are limited abilities to indicate ADS-B failures. Mode S transponders with ADS-B functionality may indicate a device failure (loss of transponder/ADS-B) and input failures (loss of position source, such as the Global Navigation Satellite System (GNSS)) with the same indicator light. Operators should refer to their AFM, AFMS, RFM, RFMS, POH, and other handbooks and manuals for information on the differences between device failures and function failures and the implications and procedures associated with each failure type. In particular, normal GNSS signal interference on the ground caused by nearby obstacles, such as a large hangar, may be incorrectly interpreted as a failure of the ADS-B system. Moving the aircraft clear of obstructions may be all that is needed to clear an indicated malfunction caused by GNSS multipath signals. 4.2.3 Transponder Operation and ADS-B Transmissions. For ADS-B system installations integrated within a transponder that share control features, operators should be aware that disabling the transponder will also disable ADS-B transmissions, as well as result in a loss of Secondary Surveillance Radar (SSR) services and Airborne Collision Avoidance System (ACAS)/ACAS II operation, if so equipped. 4.3 ADS-B Equipment Operations (U.S. Airspace). 4.3.1 Transmit Requirements. In accordance with 14 CFR § 91.225(f), each person operating an aircraft equipped with ADS-B Out must operate this equipment in the transmit mode at all times, unless authorized by the FAA or directed by air traffic control (ATC). This equipment operation requirement pertains to all phases of flight operation, including airport surface movement area operations. Pilots should select the transponder mode that enables the altitude reporting and ADS-B Out transmissions any time their aircraft is positioned on any portion of an airport movement area. Note: Aircraft must comply with the appropriate Technical Standard Order (TSO) performance requirements when transmitting ADS-B data. ### Page 14 4-2 4.3.1.1 Departures. Select the transponder mode that allows altitude reporting and enable ADS-B Out during pushback or taxi-out from parking spot. Select traffic advisory (TA) or TA/Resolution Advisory (RA) (if equipped with ACAS) when taking the active runway. 4.3.1.2 Arrivals. After clearing the active runway, if ACAS-equipped (TA or TA/RA), select the transponder to altitude reporting mode, and maintain ADS-B Out transmissions. Select “STBY” or “OFF” for the transponder and ADS-B only upon arriving at the aircraft’s parking spot or gate. 4.3.1.3 Formation Operations. ATC uses established transponder and ADS-B transmission procedures when participating in formation operations. Refer to the Aeronautical Information Manual (AIM), Paragraph 4-1-20, Transponder and ADS-B Out Operation, for specific procedures for both formation flights receiving ATC services, and visual flight rules (VFR) formation flights not receiving ATC services. 4.3.1.4 Inoperative ADS-B Out. For operations with inoperative ADS-B Out, comply with the requirements of 14 CFR § 91.213 as appropriate for your aircraft. If you intend to operate in airspace described in 14 CFR § 91.225, see paragraph 4.3.3 and comply with 14 CFR § 91.225(g)(1). 4.3.2 Equipment Qualification Requirements. In order to operate an aircraft in airspace defined in 14 CFR § 91.225, the installed ADS-B Out equipment, and its connected or internal position source, must meet the performance requirements of the applicable TSOs and meet the requirements of 14 CFR § 91.227. Since 14 CFR § 91.225 requires the equipment components to be installed, portable ADS-B Out equipment, including system components and antennas, do not comply with the rule. Operators should also note that FAA regulations require installed equipment to function as intended. Under 14 CFR part 21, installed equipment need not be manufactured under a TSO Authorization (TSOA), but must be approved or qualified according to the type of aircraft as follows: 4.3.2.1 Type-Certificated Aircraft. ADS-B Out systems and equipment (including the connected position source) installed or used in type-certificated aircraft must have a design approval issued under 14 CFR part 21 or must be installed by field approval, if appropriate. AC 20-165, Airworthiness Approval of Automatic Dependent Surveillance - Broadcast OUT Systems, provides guidance on installation of ADS-B Out systems. FAA Policy Memorandum, Installation Approval for ADS-B OUT Systems, dated March 2, 2016, provides information on how ADS-B systems may be installed by field approval. 4.3.2.2 Special Light-Sport Category Aircraft (SLSA). Equipment installed on SLSA must be installed in accordance with an applicable consensus standard and must be authorized by the aircraft’s manufacturer or a person acceptable to the FAA (refer to 14 CFR § 21.181). For equipment to be installed in SLSA, manufacturers should develop installation instructions to facilitate the ### Page 15 4-3 equipment’s installation in accordance with applicable consensus standards for SLSA. 4.3.2.3 Experimental Aircraft, Including Experimental Light-Sport Aircraft (ELSA). 4.3.2.3.1 For experimental category aircraft, including ELSA, there is no FAA approval required for the ADS-B Out system installation. However, to protect all users of the National Airspace System (NAS), it is essential for all aircraft, including experimental and ELSA, to install equipment that has been adequately designed and tested to meet the equipment’s intended functions of supporting safe ATC separation services and providing accurate traffic awareness to other aircraft. To meet this requirement, owners of these aircraft may elect to install equipment manufactured under a TSOA, in accordance with the installation instructions provided by the manufacturer. Alternatively, owners of these aircraft may elect to install equipment that are not approved under a TSOA. For non-TSOA equipment, the owner should obtain installation instructions that include a statement of compliance (SOC) from the applicable avionics manufacturer(s). To qualify non-TSOA equipment as compliant for operations in ADS-B airspace defined in 14 CFR § 91.225, the SOC should indicate that when installed in accordance with the installation instructions, the equipment complies with all requirements of 14 CFR § 91.227, and with the performance requirements of the appropriate TSO. While the SOC is important for showing compliance of the installation to 14 CFR § 91.225, it is critical to perform the installation correctly for the equipment to operate properly. 4.3.2.3.2 Owners of experimental aircraft should retain the installation instructions from the equipment supplier, including the SOC, in the aircraft records. The SOC documents the equipment’s compliance with the requirements of 14 CFR §§ 91.225 and 91.227, and retaining the installation instructions will assist in resolving in-service issues if necessary. 4.3.2.4 All Aircraft—Importance of Proper Installation. Experience with FAA compliance monitoring of ADS-B Out-equipped aircraft to date has revealed that many equipped aircraft have deficiencies with ADS-B Out system performance following initial installations. Many of these deficiencies have been traced to improper installation and incorrect system configuration. Therefore, the FAA considers it particularly important for equipment manufacturers to provide installation instructions that are as clear and easy to follow as possible and to revise these instructions when deficiencies in the instructions are discovered. Installers should adhere to the manufacturer’s installation instructions and employ practices that consistently result in ADS-B Out system installations that comply with 14 CFR § 91.227 equipment performance requirements. ### Page 16 4-4 4.3.2.5 All Aircraft—ADS-B Out Equipment Performance and FAA Monitoring. 4.3.2.5.1 The ADS-B Out rule does not impose additional continued/recurrent airworthiness inspection requirements for applicable equipment. Therefore, owners/operators of ADS-B Out-equipped aircraft should ensure continued compliance of applicable equipment performance requirements following initial installation or any subsequent alteration to the system. Note: Transponder-based ADS-B Out systems (i.e., 1090ES) are still required to meet the requirements of 14 CFR § 91.413. 4.3.2.5.2 The FAA continuously monitors the equipment performance of all ADS-B Out-equipped aircraft operating in U.S. airspace for compliance of regulatory requirements specified in 14 CFR § 91.227. Applicable equipment performance monitoring is conducted by a tool known as the ADS-B Performance Monitor (APM). 4.3.2.5.3 The APM collects data transmitted by ADS-B Out-equipped aircraft monitored on the surface and airborne. The APM applies established compliance criteria to collected data for more than 40 individual equipment performance checks, assembles relevant information into a flight record, and identifies exceptions to applicable regulations to support various internal and external reporting requirements. Aircraft identified by the APM with exceptions are referred to as non-performing equipment (NPE). 4.3.2.5.4 While the term NPE is generally used to describe aircraft with ADS-B Out equipment performance exceptions, certain pilot actions can result in NPE conditions. Such pilot actions may include the following: 1. Movement of aircraft on the surface (under its own power) or while airborne with ADS-B Out equipment turned off; 2. Operating with a nonconforming or unauthorized local call sign or flight identification (FLT ID) code; 3. Operating with an FLT ID code that does not correspond to the code filed on an associated flight plan (FP) (as applicable); 4. Operating with barometric altitude reporting off (when not directed to do so by ATC); 5. Operating a Universal Access Transceiver (UAT) transponder-dependent device with the transponder turned off (no barometric altitude or Mode A code present in ADS-B messages); and 6. Operating ADS-B Out equipment in any manner contrary to applicable regulations. ### Page 17 4-5 4.3.2.5.5 As discussed in paragraph 4.2, pilots should be familiar with the operation of ADS-B Out equipment, including any associated failure indications provided by the system. It is important for pilots to understand that most ADS-B failure indications are limited to system component failures; and indications associated with equipment performance required by regulation are not provided. 4.3.2.5.6 To enable public access to ADS-B equipment performance data needed for owners/operators to verify compliance with 14 CFR § 91.227 requirements, the FAA provides a free, web-based service called the Public ADS-B Performance Report (PAPR) at https://adsbperformance.faa.gov/PAPRReques t.aspx. Additional information on the PAPR service can be found at https://www.faa.gov/air_traffic/technology/equipadsb. 4.3.2.5.7 The FAA recommends that owners/operators of ADS-B Out-equipped aircraft verify equipment performance through frequent use of the PAPR request service, especially following initial equipment installation, modification, or maintenance of existing ADS-B Out systems (including component software updates/changes). 4.3.2.6 Handling of Aircraft With NPE. 4.3.2.6.1 When ADS-B Out equipment performance becomes deficient during flight, ATC may direct the pilot to discontinue ADS-B Out transmissions pursuant to 14 CFR § 91.225(f)(2). The pilot should comply with the procedures established for that aircraft or notify ATC if unable. If necessary, ATC may direct the aircraft to exit 14 CFR § 91.225 airspace. 4.3.2.6.2 FAA flight monitoring has shown that aircraft engaged in aerobatic and agricultural operations may fail to meet applicable equipment performance requirements due to maneuvering that exceeds the design limits of the installed GNSS equipment. Aircraft identified by the APM with exceptions to 14 CFR § 91.227 resulting from maneuvering characteristics of aerobatic and/or agricultural operations are not considered NPE by the FAA. When not actively engaged in aerobatics or agricultural operations (e.g., when transiting to and from applicable areas of operation), these aircraft are expected to meet ADS-B Out equipment performance requirements. 4.3.2.6.3 In late 2017, the FAA published a notice to the Federal Register (FR) announcing changes to ADS-B services, including the Traffic Information Service-Broadcast (TIS-B) (refer to 82 FR 60302, Docket Number FAA-2017-1194, Change to Automatic Dependent Surveillance Broadcast Services, at https://www.federalregister.gov). These changes included implementation of a filter within the FAA ATC automation system to prevent processing of data transmitted by certain NPE aircraft. Application of the filter is enabled by restricting use of the 24-bit International Civil Aviation Organization (ICAO) address (Mode S code) transmitted from NPE aircraft ### Page 18 4-6 and managed through a list referred to as the No Services Aircraft List (NSAL). NPE aircraft on the NSAL cannot be provided ATC services via the ADS-B data network and do not meet the equipment performance requirements necessary to qualify for TIS-B client services. Owners/operators of aircraft on the NSAL must seek authorization from ATC to operate in the airspace specified by 14 CFR § 91.225. 4.3.2.6.4 Prior to listing NPE aircraft on the NSAL, the FAA will provide written notification of relevant ADS-B equipment issues to the owner/operator at the address associated with the aircraft’s registry in an effort to coordinate NPE corrective action. In cases where the FAA makes notification of NPE to an owner/operator via an individual FAA letter of finding (LOF), the owner/operator has 45 days from the date of the LOF to respond to the FAA to establish a plan of corrective action for the NPE. All NPE aircraft are subject to being placed on the NSAL if contact is not established with the FAA to communicate a plan for corrective action within the 45-day period. Note: NPE notifications mailed to unmonitored mailboxes may result in aircraft being listed to the NSAL (after 45 days) without owner/operator awareness. Owners/operators with addresses associated with an unmonitored mailbox (e.g., LLC or nonresident addresses) are advised to request a PAPR for awareness of ADS-B Out equipment performance and the NSAL status of their aircraft. 4.3.2.6.5 Additionally, the FAA has implemented a process to provide an automated report indicating potential NPE for aircraft operated by a specific certificate holder (CH). The report is called the Fleet Report Avionics Trend Analysis Tool (ATAT). In cases where the FAA makes notification of NPE (or potential NPE) via this report, the receiving CH, along with the FAA Certificate Management Team (CMT), should coordinate with the appropriate office within the FAA Flight Standards Aircraft Maintenance Division to discuss the identified potential NPE in the report, as necessary. This coordination should occur in a timely manner as much as practical. The 45-day period that is associated with the individual LOF sent to an aircraft owner/operator does not apply to those receiving the automated Fleet Report ATAT. 4.3.2.6.6 The operation of aircraft with certain NPE characteristics (e.g., erroneous position reports) present a significant safety hazard to surrounding airspace and ATC services. Hazardous NPE aircraft may require immediate placement on the NSAL to mitigate applicable safety risks prior to owner/operator notification. 4.3.2.6.7 In rare cases, it is necessary for the FAA to issue an Aircraft Condition Notice (FAA Form 8620-1) to prevent operation of aircraft with hazardous NPE characteristics. ### Page 19 4-7 4.3.2.6.8 Owners/operators receiving an NPE notification letter and/or Aircraft Condition Notice should follow the instructions provided in those documents and contact the handling aviation safety inspector (ASI) as soon as possible to coordinate required corrective action. Following NPE corrective action, a verification flight must be conducted pursuant to 14 CFR § 91.407(b), and the handling ASI should be notified, to validate equipment performance. When the handling ASI determines the NPE condition has been corrected, they will notify the owner/operator and, when applicable, initiate the process for removal of the aircraft from the NSAL. Note: Once requested, removal of aircraft from the NSAL can take up to 30 days. 4.3.2.6.9 Aircraft on the NSAL are identified on the cover page of an applicable PAPR with the following language (in red font): Aircraft is on No Services List. This language is omitted from a PAPR associated with aircraft not currently on the NSAL. See paragraph 4.3.2.5.6 for information on obtaining a PAPR. 4.3.3 Operation of Aircraft With Inoperative ADS-B. Title 14 CFR § 91.225(g) permits ATC to authorize the operation of aircraft with inoperative ADS-B or that do not have ADS-B installed into airspace where it is required. Under 14 CFR § 91.225(g), operators must make requests for ATC-authorized deviations from the requirements in 14 CFR § 91.225 to the ATC facility that has jurisdiction over the concerned airspace or airport movement area within the time periods specified below: 1. For operation of an aircraft with inoperative ADS-B equipment to the airport of ultimate destination (including any intermediate stops) or to proceed to a place where suitable repairs can be made, or both, the request may be made at any time. 2. For operation of an aircraft that is not equipped with ADS-B, operators must make the request at least 1 hour before the proposed operation. 4.3.4 Procedures for Requesting and Authorizing Deviations. In order to standardize the process for requests and document authorized deviations, the FAA has established the following sets of procedures: one for air carrier operators and another for all others. 4.3.4.1 Air Carriers Procedures. For departures within 2 hours of the request, the air carrier should contact the FAA Joint Air Traffic Operations Command (JATOC) telephonically (540-422-HELP (4357)) for approval of the immediate operation. For departures that are more than 2 hours from the request, email the ADS-B Deviation Authorization Preflight Tool (ADAPT) Help Desk (adapthelp@faa.gov) and include the following information: aircraft registration number (and flight number(s)), proposed departure and destination airport(s), flight dates, number of operating days, planned date of repair, confirmation that the aircraft transponder is functioning, and air carrier email point of contact (POC). The JATOC will relay the approval or denial by email. ### Page 20 4-8 Note: To request an authorized deviation for inoperative ADS-B between the hours of 2201–0559 eastern time, make the request directly with the appropriate ATC facility, as directed by regulation (summarized in paragraph 4.3.3). 4.3.4.2 All Other Operators. All other operators are encouraged to use ADAPT to document your request and authorization (see paragraph 4.3.6). You may also request coordination through the departure airport ATC tower. Note 1: Aircraft must have an operable transponder with Mode C altitude reporting capability to use ADAPT. If the failure results in the loss of all transponder functions, you must coordinate through the Air Traffic Control System Command Center (ATCSCC) or the local facility, as appropriate, or use your existing procedures for an inoperative transponder. Note 2: All airborne failures will be handled by the FAA facility where the failure occurs. The FAA facility will coordinate through the ATCSCC if necessary, which will then coordinate with all FAA facilities along the remaining route of flight. 4.3.5 Operation of Aircraft Not Equipped With ADS-B. In April 2019, the FAA published a notice to the FR clarifying policy for authorizations to operators of aircraft not equipped with ADS-B (refer to 84 FR 12062, Docket Number FAA-2019-0239, Statement of Policy for Authorizations to Operators of Aircraft That Are Not Equipped With Automatic Dependent Surveillance-Broadcast (ADS-B) Out Equipment, at https://www.federalregister.gov). Operators are encouraged to review the notice, summarized below. 4.3.5.1 To operate in ADS-B airspace, an operator whose aircraft is not equipped with ADS-B Out equipment must obtain a preflight authorization in accordance with 14 CFR § 91.225(g). The operator has the responsibility to obtain a preflight authorization from ATC for all ADS-B Out airspace on the planned flightpath. For the reasons explained in the policy, however, the FAA will be very unlikely to issue routine and regular authorizations to scheduled operators seeking to operate nonequipped aircraft in rule airspace. Likewise, although unscheduled operators may request authorizations for airspace at capacity constrained airports as defined in the policy, issuance of an authorization may prove difficult to obtain. 4.3.5.2 Note that the provision of air traffic services to a non-ADS-B-equipped aircraft whose flight transits ADS-B Out airspace will not constitute authorization under 14 CFR § 91.225(g). Although ATC will be able to observe that an aircraft is not equipped with ADS-B Out equipment, ATC will not be responsible for determining whether nonequipped aircraft operating in the NAS are properly authorized to operate in ADS-B Out airspace. The provision of air traffic services is separate from and will not constitute an ### Page 21 4-9 authorization to deviate from the ADS-B Out equipage requirements while operating in that airspace. The nonequipped operator, as always, will have the responsibility to ensure compliance with the regulations, which includes obtaining a preflight authorization in accordance with 14 CFR § 91.225(g). 4.3.6 ADAPT. The FAA developed ADAPT, a web-based mechanism for requesting authorization in accordance with the regulation and this policy. You may access ADAPT at https://sapt.faa.gov. While ADAPT is intended primarily for requests to operate without ADS-B, you may also choose to use it as a means to request an authorization to operate with inoperative ADS-B. Refer to the ADAPT User Guide for additional information. Air carriers are not precluded from using ADAPT; however, there is no guarantee that an automatic authorized deviation will be issued. 4.4 Flight Plans (FP). The information to complete the ICAO FP continues to evolve with the introduction of Next Generation Air Transportation System (NextGen) equipment and capabilities. The information provided here represents just some of the ADS-B specific information elements. For the most current and complete instructions and descriptions of FP filing codes, refer to AIM, Paragraph 5-1-9, Single Flights Conducted With Both VFR and IFR Flight Plans, and the FAA Flight Planning Information web page at https://www. faa.gov/about/office_org/headquarters_offices/ato/service_units/air_traffic_services/fligh t_plan_filing. 4.4.1 ICAO FP Item 10, Equipment. When operating aircraft equipped with ADS-B you should indicate surveillance equipment in Item 10 of the ICAO FP (FAA Form 7233-4, Pre-Flight Pilot Checklist and International Flight Plan). In addition to the transponder codes (refer to AIM, paragraph 5-1-9), you should include an ADS-B capability code from the following list. Note that FAA automation does not process ADS-B reports on Very High Frequency (VHF) Digital Link Mode 4, so those codes are not listed here. 4.4.2 ADS-B Capability Codes. The ADS-B capability codes are as follows: • B1: ADS-B with dedicated 1090-megahertz (MHz) ADS-B Out capability. • B2: ADS-B with dedicated 1090 MHz ADS-B Out and In capability. • U1: ADS-B Out capability using UAT. • U2: ADS-B Out and In capability using UAT. Note 1: Only include an ADS-B capability code when at least one serviceable ADS-B Out system is installed. Note 2: Do not file an ADS-B code for “in” capability only. There is currently no way to indicate that an aircraft has “in” capability but no “out” capability. For aircraft with ADS-B “out” on one frequency and “in” on another, include only the ADS-B “out” code. (e.g., B1 or U1). ### Page 22 4-10 4.4.3 ICAO FP Item 18, Other Information. 4.4.3.1 SUR/A2: If you file an ADS-B capability code of B1 or B2 in Item 10 and the ADS-B equipment complies with 14 CFR § 91.225, include the item “SUR/A2” in Item 18. This indicates the aircraft has 1090 MHz Extended Squitter (ES) ADS-B compliant with RTCA DO-260B, Minimum Operational Performance Standards for 1090 MHz Extended Squitter Automatic Dependent Surveillance - Broadcast (ADS-B) and Traffic Information Services - Broadcast (TIS-B), or RTCA DO-260C as modified by RTCA DO-260C Change 1. 4.4.3.2 SUR/A2: If you file an ADS-B capability code of U1 or U2 in Item 10 and the ADS-B equipment complies with 14 CFR § 91.225, include the item “SUR/A2” in Item 18. This indicates the aircraft has 978 MHz UAT ADS-B compliant with RTCA DO-282B, Minimum Operational Performance Standards for Universal Access Transceiver (UAT) Automatic Dependent Surveillance - Broadcast (ADS-B), or RTCA DO-282C. Note: If the ADS-B capability filed in Item 10 is not compliant with 14 CFR § 91.225, do not include “SUR/” information in this FP field. 4.4.4 Anonymity Operations and VFR FPs. Title 14 CFR § 91.227 contains specific provisions allowing operators with TSO-C154c or TSO-C154d, Universal Access Transceiver (UAT) Automatic Dependent Surveillance - Broadcast (ADS-B) Equipment Operating on the Radio Frequency of 978 Megahertz (MHz), equipment to transmit a self-assigned (randomized) temporary 24-bit address and no Aircraft Identification (ACID). However, pursuant to the regulations (14 CFR § 91.227(d)(11)), the UAT self-assigned temporary 24-bit address feature may only be used when the operator “has not filed a flight plan” and “has not requested ATC services.” The FAA interprets the exceptions in 14 CFR § 91.227(d)(8) and (11) as applying to pilots who: (1) have not filed an instrument flight rules (IFR) FP; (2) have not requested ATC services, such as separation services or VFR flight following; and (3) are using a TSO-C154c or TSO-C154d self-assigned temporary 24-bit address. As a result, VFR pilots using the anonymity feature may file a VFR FP, which enables search-and-rescue capabilities, provided they do not request flight following. Note: For any operation where ATC assigns you a discrete Mode A code, you are receiving ATC services. 4.4.5 Privacy ICAO Address (PIA) Program. The FAA acknowledges the desire of some operators to limit the availability of real-time ADS-B position and identification information for a specific aircraft. To address privacy concerns and to accommodate the needs of aircraft, participation will be subject to the following conditions and limitations: • U.S. registered. • 1090 MHz ADS-B equipped. ### Page 23 4-11 • Using a third-party call sign. • Flying in domestic U.S. airspace, as well as offshore within U.S.-controlled flight information regions (FIR). 4.4.5.1 The PIA program will enable interested aircraft owners to request an alternate, temporary ICAO aircraft address, which will not be assigned to any owner in the Civil Aviation Registry (CAR). This service will be available in two phases: 1. Phase 1: The application for PIA can be accessed on the FAA website at https://www.faa.gov/air_traffic/technology/equipadsb/privacy. This service will be operated, monitored, and maintained by the FAA. 2. Phase 2: The service will be transitioned to third-party service provider(s) who will operate, monitor, and maintain this program, which will continue to be available from the above website. 4.4.5.2 To maintain the safety and integrity of air traffic operations, the FAA monitors PIA use in the NAS. The following list includes improper uses of PIAs: • Use of PIAs assigned to another aircraft. • Use of unassigned PIAs. • PIAs used for operations outside of U.S.-controlled FIRs. • PIAs changed in flight. • PIAs used with an underperforming ADS-B emitter. • PIA used with a UAT or dual 1090/UAT emitter. 4.4.5.3 PIAs used by an aircraft other than the aircraft to which the address is assigned results in a violation of 14 CFR § 91.227 and notification to the FAA. Upon detection of improper PIA use, the aircraft owner/operator will be issued a warning that requires immediate action to remedy the issue before the next operation involving the assigned PIA. Failure to comply may result in the revocation of the PIA assignment. Upon revocation of the PIA assignment, the aircraft would be required to fly with its original ICAO aircraft address as found in the CAR, and failure to do so may result in regulatory enforcement action by the FAA and cessation of additional PIA assignments to that aircraft until the enforcement action is closed. 4.4.5.4 An aircraft operator may use the ICAO aircraft address originally assigned and recorded in the CAR at any time for operations, including any time while having an active PIA assignment. Use of the assigned ICAO aircraft address recorded in the CAR is required for all flights leaving U.S. sovereign airspace, and it may be used for any other flights at any time, as desired by the aircraft operator. ### Page 24 4-12 4.4.5.5 The FAA requires that the user submits documented validation that an ICAO aircraft address has been correctly installed into the aircraft’s ADS-B avionics after each change. Refer to the FAA PIA web page for complete program details. 4.5 Preflight Requirements (U.S. Airspace). Note: The remainder of paragraph 4.5 describes additional preflight considerations that only apply to the operation of aircraft equipped with selective availability (SA) On position sources, as further described in paragraph 4.5.1.2. 4.5.1 Flight Planning Requirements for Certain Operators. Under 14 CFR § 91.103, pilots and operators must use all available information in planning their flight, to ensure that the performance requirements will be met for the duration of the flight. Variations in position source performance affect ADS-B Out in two specific broadcast elements required by 14 CFR § 91.227: Navigation Accuracy Category for Position (NACp) and Navigation Integrity Category (NIC). During certain Global Positioning System (GPS) constellation geometries, some position sources may produce values for NACp and NIC that are less than required by the rule. 4.5.1.1 Four different variants of GPS receivers are currently in use as a position source that can meet ADS-B Out rule performance requirements, to varying degrees, when adequate numbers of GPS satellites are in view. SA is a feature that deliberately degraded the GPS satellite signal, resulting in a less accurate reported position. SA was deactivated in 2000. 4.5.1.2 SA-On GPS receivers assume SA is still active (on), thereby unnecessarily inflating integrity and accuracy bounds of the positions that are no longer degraded by SA. Most GPS receivers that are only compliant with TSO-C129, Airborne Supplemental Navigation Equipment Using the Global Positioning System (GPS), are SA-On receivers. 4.5.1.3 SA-Aware GPS receivers are designed to recognize that SA is inactive and optimize the performance from GPS. GPS receivers that comply with the performance requirements of TSO-C196, Airborne Supplemental Navigation Sensors for Global Positioning System Equipment Using Aircraft-Based Augmentation, are SA-Aware receivers. 4.5.1.4 Satellite-Based Augmentation System (SBAS) receivers also use the additional signals from geostationary satellites specifically designed for aviation use, improving the quality and robustness of positioning performance. This difference in performance is most pronounced for very precise operations, such as localizer performance with vertical guidance (LPV) approaches, and for all operations when there are inoperative GPS satellites. GPS receivers complying with TSO-C145, Airborne Navigation Sensors Using the Global Positioning System Augmented by the Satellite Based Augmentation System (SBAS), or TSO-C146, Stand-Alone Airborne ### Page 25 4-13 Navigation Equipment Using the Global Positioning System Augmented by the Satellite Based Augmentation System (SBAS), are SBAS receivers. 4.5.1.5 Aircraft-Based Augmentation System (ABAS) sensors tightly integrate GPS measurements with inertial reference/navigation sensor data, improving the quality and robustness of positioning performance. This difference in performance is most pronounced for lower level Required Navigation Performance (RNP) operations, such as Area Navigation (RNAV) approaches, and for all operations when there are inoperative GPS satellites. Note 1: Some GPS receivers manufactured with a TSO-C129a approval are SA-Aware, and, therefore, have the same NACp and NIC availability as TSO-C196( )-approved equipment. Operators should check with their GPS receiver supplier to verify whether their installed TSO-C129( ) GPS receiver is SA-On or SA-Aware. Note 2: The Wide Area Augmentation System (WAAS) is the designation of the SBAS available in North America and is the term often used when making reference to SBAS in the United States. 4.5.2 GPS Performance Prediction. For aircraft equipped with TSO-C129( ) GPS units to support ADS-B Out equipment, an NACp and NIC GPS service availability prediction should be performed for the intended route of flight (route and time) using available GPS satellite information and guidance published in this AC. It is not necessary for operators of aircraft equipped with the following receivers to conduct a preflight availability prediction: WAAS (TSO-C145 or TSO-C146), SA-Aware (TSO-C196), TSO-C129a receivers that are SA-Aware, or ABAS that include SA-Aware GPS receivers. 4.5.2.1 Prediction Methods. Operators may use any of the following preflight availability prediction methods. 4.5.2.1.1 Operators of large fleets of aircraft or users of flight planning programs may wish to use their own preflight availability verification tool. The operator is responsible for selecting a tool that accurately predicts the ADS-B position source performance for their aircraft. The tool needs to account for the GPS satellites that are in service at the time of the prediction, and may take into account unique characteristics of the GNSS receiver, aircraft integration, or installation, including performance better than required in FAA standards or use of inertial information integrated into the ADS-B Out position source. The FAA does not evaluate or approve a particular tool, but may evaluate the basis of the operator’s determination that the tool is appropriate to their aircraft, particularly if its use results in noncompliant flights in airspace where ADS-B Out is required. 4.5.2.1.2 Operators may use the FAA-provided preflight availability prediction tool, called the Service Availability Prediction Tool (SAPT) (https://sapt.faa.gov). Refer to the SAPT User Guide for specific instructions on its use. ### Page 26 4-14 4.5.2.1.3 Operators may use a third-party interface, incorporating FAA GPS performance prediction data without altering performance values, to predict NACp/NIC performance outages for the aircraft’s predicted flightpath and times. 4.5.2.2 Prediction Model Parameters. The operator should use a model appropriate to their equipment, including the type of GPS receiver and the demonstrated capability to track satellites at a given mask angle. When selecting a mask angle, the operator should consider the equipment qualification, installation in the aircraft, and the effects of normal maneuvering. Aircraft are typically qualified with a 5-degree mask angle, and operational experience has indicated that a 2-degree mask angle can be achieved by some equipment installations. If using the SAPT, each prediction is valid for the operation within 5 minutes of the plan time and 7.5 nautical miles (NM) of the route. The operator may wish to submit additional requests for predictions for varying times around the proposed departure time to ensure compliance at the actual departure time. 4.5.2.3 Flight Planning Guidance. Predictions should be conducted within 24 hours of departure and as close to departure time as feasible, but with sufficient time to replan the flight in the event a segment along the planned route is predicted to have insufficient GPS service availability. The prediction should be reevaluated prior to flight if new information (i.e., a Notice to Air Missions (NOTAM)) provides notice of an unscheduled GPS satellite outage. In the event of a predicted loss of performance for any part along the intended route in the airspace where ADS-B Out is required, the flight should be replanned so that ADS-B Out performance requirements specified in 14 CFR § 91.227 can be met. 4.5.3 Preflight Prediction Compliance. Operators need to perform an ADS-B Out preflight prediction only for the intended route of flight to the intended destination. For example, when departure and/or arrival alternate airports are required, no preflight prediction is necessary for these routes. However, if you become aware of a change that could result in degraded ADS-B Out performance, such as a satellite outage prior to receiving an ATC clearance for the intended route of flight, then you should conduct a subsequent preflight prediction for the planned flight. This will ensure that ADS-B Out performance is still predicted to comply with the performance requirements of 14 CFR § 91.227(c)(1)(i) and (iii). Once the pilot has received an ATC route clearance, there is no requirement to conduct a subsequent preflight prediction. Therefore, upon receiving a satisfactory preflight availability prediction and an ATC clearance for an intended route of flight, the operator will be deemed to have complied with the preflight availability prediction requirement and the performance requirements of 14 CFR § 91.227(c)(1)(i) and (iii). The FAA accepts that unanticipated changes in route of flight and environmental conditions may adversely affect ADS-B Out performance. ATC will continue to exercise its responsibility for the safe and efficient movement of air traffic, including the routing of traffic to meet those objectives. ADS-B preflight planning should include: ### Page 27 4-15 • Identification of flights or aircraft that require completion of a preflight prediction. • Identification of the preflight prediction system (or systems) to be used. • A means to document completion of a satisfactory prediction for each flight where a prediction is required. • Retention of prediction completion documentation for a suitable period of time, such as 3 months. 4.5.4 GPS Interference With ADS-B Compliance. There may be times when the GPS position source cannot meet the required technical performance for compliance with 14 CFR § 91.227 due to planned GPS interference. In the event of a scheduled interference outage of GPS, the FAA will issue a NOTAM that identifies the airspace and time periods that may be affected by the interference. The FAA has determined that it would be impractical and not in the public interest to require operators to avoid the affected area based on the chance that an otherwise compliant flight could experience GPS interference. Accordingly, operators should proceed with their intended operation if the only impediment to their operation is possible planned GPS interference. An operator who is required to perform a preflight availability prediction for the intended route of flight is still required to obtain a satisfactory preflight availability prediction. When a NOTAM identifies the airspace and time periods that may be affected by GPS interference, an operator will not be required to alter their route of flight to avoid the area based solely on that NOTAM. If an operator encounters actual GPS interference during their flight that results in a degradation of ADS-B Out performance, provided the operator has taken the appropriate preflight actions, the FAA will not consider these events to constitute a violation, as such application of the regulation would impose standard of conduct wholly outside the operator’s control. 4.5.5 SAPT Outages. The FAA will issue a NOTAM in the event of a SAPT outage. Operators who use SAPT as their preflight prediction tool will not need to conduct a preflight prediction for the duration of the outage. Additionally, any FPs submitted to ATC with a proposed departure time within 90 minutes of SAPT return to service do not require a subsequent preflight analysis. When there is a SAPT outage and an operation falls below the performance requirements, provided the operator has taken the appropriate preflight actions with regard to relying upon SAPT, the FAA will not consider these events to constitute a violation, as such application of the regulation would impose standard of conduct wholly outside the operator’s control. For operators who have been notified by the FAA of consistent and repeated ADS-B Out performance issues, the FAA cautions that operating during a SAPT outage without first redressing the identified nonperformance issue will be considered a continuation of existing noncompliance of the performance requirements. 4.6 Flightcrew Entry of Required ADS-B Data. The operator should develop operational procedures to address flightcrew entry of the ADS-B message elements required in 14 CFR § 91.227 and as described in paragraphs 4.6.1 through 4.6.4. If the ADS-B avionics system design does not allow for a single point of entry for this information, the AFM, AFMS, RFM, RFMS, POH, or other required flight manual must address the ### Page 28 4-16 requirement to enter the information multiple times through the appropriate system’s interface and to ensure that conflicting ACID information is not transmitted to ATC. 4.6.1 Mode A Code. 4.6.1.1 ATC automation relies on the Mode A code to identify aircraft under radar surveillance and to correlate the displayed target to an FP. The Mode A code is one element of the transmitted ADS-B message set. Since SSR and ADS-B surveillance will overlap in much of the NAS, correlation of the Mode A code between the transponder and the ADS-B message is necessary to ensure that a single target is resolved and correlated to an FP route. 4.6.1.2 It is imperative that the ATC-assigned transponder code is identical to the one in the ADS-B Out message. Refer to AC 20-165 for more information. Note: Transmission of conflicting transponder and ADS-B Mode A codes will result in erroneous traffic conflict alerts within the ATC automation system. 4.6.2 Aircraft’s FLT ID. 4.6.2.1 An aircraft’s FLT ID is transmitted by the ADS-B Out avionics. Per 14 CFR § 91.227(d)(8), the FLT ID must be identical to the “Aircraft Identification” as entered in Item 7 of FAA Form 7233-4 and Item 2 of FAA Form 7233-1, Flight Plan, which limit it to a maximum of seven alphanumeric characters. It is also referred to as a call sign. The FLT ID is typically entered by the flightcrew during preflight through either a flight management system (FMS) interface (control display unit (CDU)) or transponder control panel. The FLT ID for General Aviation (GA) aircraft is typically the aircraft’s registration number. The aircraft owner can preset the FLT ID to the aircraft’s registration number (e.g., N235RA), since it is a fixed value, or the pilot can enter it into the ADS-B Out system prior to flight, provided the ADS-B avionics have this capability. It is important to know that the FLT ID should be input into the ADS-B system exactly as filed in Item 2 of FAA Form 7233-1 or Item 7 of FAA Form 7233-4. No additional characters should be used to fill all available fields. 4.6.2.2 Some ATC systems use transmitted FLT IDs to uniquely identify each aircraft within a given airspace and correlate them with a filed FP for the provision of surveillance and separation services. If the FLT ID is not entered correctly, ATC automation systems may not associate surveillance tracks for the aircraft to its filed FP. Therefore, air traffic services may be delayed or unavailable until this is corrected. Consequently, it is imperative that flightcrews and GA pilots ensure the FLT ID entry correctly matches the ACID annotated in the filed ATC FP prior to departure. 4.6.2.3 In FAA ATC systems, if the FLT ID transmitted by the aircraft’s ADS-B system does not exactly match the FLT ID on the FP, a call sign mismatch ### Page 29 4-17 (CSMM) occurs. When a CSMM occurs and the ATC functionality is enabled, the controller is alerted and may take action, resulting in a flight delay. Furthermore, ATC may elect to advise the Flight Standards Service (FS) of the event and the potential violation of 14 CFR § 91.227(d)(8). The specific wording of this regulation has caused misunderstanding from numerous operators and airmen who believe it is acceptable to have a different FLT ID on the FP [ABC1234] from the FLT ID [N12345] transmitted by ADS-B. In an August 3, 2017, legal interpretation, the FAA Office of the Chief Counsel found that the intent of 14 CFR § 91.227(d)(8) is to require that the FLT ID as entered on the FP must exactly match the ADS-B-transmitted FLT ID. See Table 4-1, Aircraft Identification Transmission Examples, for examples. Table 4-1. Aircraft Identification Transmission Examples Flight Plan Aircraft ID Correct ADS-B Transmission Incorrect ADS-B Transmission AAL5688 AAL5688 AAL-5688 SWA2155 SWA2155 2155 UAL21 UAL21 UAL0021 DAL9450 DAL9450 N561DL ASH5861 ASH5861 ASH5872 N350QS N350QS EJA350 FDY1055 FDY1055 VFR N777JK N777JK N-777JK N123DJ N123DJ NGF123 **CGABC CGABC C-GABC** **VHXYZ VHXYZ VH-XYZ N100PH N100PH N1OOPH** 4.6.2.4 GA pilots occasionally have the opportunity to use an FLT ID provided by a charity or other organization instead of using their N-number. In this situation, the GA pilot may only use the organization’s FLT ID for the flight, provided they change the FLT ID transmitted by the ADS-B Out avionics. If the ADS-B equipment does not allow the FLT ID to be changed or the pilot is unsure of how it is accomplished, the pilot should not use the organization’s FLT ID. In this case, in order to ensure compliance with 14 CFR § 91.227(d)(8), the pilot should use the aircraft registration number as the FLT ID. 4.6.2.5 Aircraft owners/operators are encouraged to periodically verify that their ADS-B is broadcasting the correct FLT ID. This is particularly true after any maintenance has been performed on the aircraft, even if not directly associated with avionics. The free FAA PAPR (described in paragraph 4.3.2.5.6) is an excellent tool to verify the output of ADS-B parameters, including FLT ID. ### Page 30 4-18 4.6.3 Emergency Status. 4.6.3.1 This ADS-B message element and transponder code alerts ATC that the aircraft is experiencing emergency conditions and indicates the type of emergency. The appropriate Mode A code should be entered into the transponder (e.g., 7500, 7600, or 7700). The ICAO Annex 10, Aeronautical Telecommunications, Volume IV, Surveillance and Collision Avoidance Systems, emergency codes (general emergency, no communications, and unlawful interference) are required by 14 CFR § 91.227. 4.6.3.2 ADS-B systems integrated within a transponder will automatically set the applicable emergency status when code 7500, 7600, or 7700 is entered into the transponder. Transponders compliant with RTCA DO-181F, Minimum Operational Performance Standards for Air Traffic Control Radar Beacon System/Mode Select (ATCRBS/Mode S) Airborne Equipment, will also automatically set the applicable emergency status when code 7400 is entered into the transponder. 4.6.4 Transponder IDENT Function. The AFM or POH will provide specific instructions on how the IDENT feature will be activated in specific installations, including any installations with multiple IDENT features. ### Page 31 Appendix A A-1 APPENDIX A. ADS-B IN-TRAIL PROCEDURE A.1 Purpose. This appendix provides a description of the ADS-B-enabled In-Trail Procedure (ITP) and guidance to operators seeking FAA authorization to conduct ITP operations. A.2 Background. The ITP is designed primarily for use in nonradar oceanic airspace to enable appropriately equipped ADS-B In aircraft to perform flight level (FL) changes previously unavailable with procedural separation minima applied. The improved traffic information available to ADS-B In-equipped aircraft allows ITP maneuvers to occur safely with reduced separation minima applied. ITP enables flightcrews to execute FL changes to improve ride comfort, avoid weather, or obtain more favorable winds to improve fuel economy and arrival times. A.2.1 ITP Scenario. Figure A-1, Reduction of Aircraft Separation Minima With In-Trail Procedure, illustrates a basic ITP scenario. The ITP aircraft (blue) wishes to climb from FL340 to 360 between two reference aircraft (red) where procedural separation minima is applied. Using onboard ADS-B In and ITP equipment, the ITP aircraft can determine if the necessary criteria can be met and, if so, request air traffic control (ATC) approval to execute the desired FL change using reduced separation minima between the two reference aircraft. A.2.2 ATC Responsibility. ATC maintains separation responsibility throughout the ITP maneuver, and resumes the appropriate separation minima at its completion. ATC will apply the reduced ITP separation only between a qualified ITP aircraft and no more than two reference aircraft for the duration of the maneuver. The ITP maneuver can be performed with reference aircraft that do not have ADS-B In equipment. To enable an ITP maneuver, it is necessary for the reference aircraft to transmit an ADS-B Out signal of sufficient quality. Figure A-1. Reduction of Aircraft Separation Minima With In-Trail Procedure A. 3 ITP Terminology. A.3.1 Closing Groundspeed (GS) Differential. The difference between the ITP aircraft’s GS and a reference aircraft’s GS that results in a reduction of the ITP distance. ### Page 32 Appendix A A-2 A.3.2 Closing Mach Speed Differential. The difference in Mach speed between the ITP aircraft and the reference aircraft that results in a reduction of the ITP distance. A.3.3 ITP Aircraft. An aircraft operated by a flightcrew authorized to conduct an ITP. A.3.4 ITP Criteria. A set of conditions to be satisfied prior to initiating or executing an ITP clearance that ensures the safety of the procedure. A.3.5 ITP Distance. The distance between the ITP aircraft and reference aircraft as defined by the difference in distance to an aircraft calculated common point along a projection of each aircraft’s track in front of or behind the aircraft, as appropriate. (See Figure A-2, In-Trail Procedure Distances Illustrated.) For the case where aircraft are on parallel tracks, the ITP distance is measured along the track of one of the aircraft using its calculated position and the point abeam the calculated position of the other aircraft. This measurement technique is similar to the method described in International Civil Aviation Organization (ICAO) Doc 4444, Procedures for Air Navigation Services—Air Traffic Management, Section 5.4.2.9, Performance-Based Longitudinal Separation Minima. A.3.6 ITP Equipment. The onboard avionics that support an ITP. A.3.7 Reference Aircraft. Aircraft (no more than two) transmitting valid ADS-B data that meet specified criteria and are referenced as part of an ITP clearance request to ATC. ### Page 33 Appendix A A-3 Figure A-2. In-Trail Procedure Distances Illustrated A. 4 ITP Concept. The ITP concept is based on the aircraft satisfying specific initial conditions and the flightcrew promptly and correctly executing the requested procedure once approved. The initial conditions are the ITP speed/distance criteria, the relative altitude criteria, the similar track criteria, and the closing Mach differential, as well as the accuracy and integrity of the ADS-B data transmitted from participating aircraft. (See Table A-1, In-Trail Procedure Initiation/Maneuver Criteria (Reference RTCA DO-312 Supplement).) The safety of the procedure depends upon the ITP aircraft maintaining ### Page 34 Appendix A A-4 constant Mach and climb or descend at a minimum of 300 feet per minute (fpm) during the maneuver. With these criteria, an ITP aircraft should never come closer than the 10-nautical-mile (NM) separation minimum to a reference aircraft while passing through their altitude(s). A.4.1 ITP Distance and GS Differential Criteria. The initial distance criteria values, 15 NM and 20 NM, were selected so that when an FL change at 300 fpm and constant Mach number is maintained with the respective maximum 20- or 30-knot closing GS differential, the distance between the aircraft should not become less than the ITP minimum separation of 10 NM. A.4.2 Relative Altitude Criteria. The design of the procedure is such that the reference aircraft may not be more than 2,000 feet above or below the ITP aircraft. A.4.3 Similar Track Criteria. Application of the ITP is limited to geometries where the ITP aircraft and any reference aircraft are on similar tracks. Similar tracks are defined here as less than 45 degrees from one another. See Figure A-3. Figure A-3. Similar Track A .4.4 Mach Differential. In order to ensure an acceptable closure throughout the ITP maneuver, the controller will not issue an ITP clearance if the closing Mach differential is greater than 0.06 Mach. This Mach differential check accounts for potentially unsafe closure rates due to abnormal or adverse wind gradient conditions at the intermediate altitudes. The Mach number check may be achieved by: 1. Using the cruise Mach numbers of the ITP and reference aircraft where the Mach number technique is being used; 2. Requesting Mach numbers from the ITP and reference aircraft; or 3. Any other methodology determined appropriate and acceptable by the regulatory authority and the air navigation service provider (ANSP). ### Page 35 Appendix A A-5 A.4.5 ADS-B Data Quality Criteria. The ITP avionics only accept ADS-B Out aircraft broadcasting data of sufficient quality for use as reference aircraft for ITP. The ITP avionics only allow ITP when own-ship data quality is sufficient to ensure safe separation. The data quality criteria are: 1. Position accuracy for ITP and reference aircraft—ITP and reference aircraft data with horizontal position accuracies of at least 0.5 NM (95 percent); 2. Position integrity for ITP and reference aircraft—ITP and reference aircraft data with horizontal position integrity bounds of 1.0 NM at 1×10E-05; and 3. Velocity accuracy for ITP and reference aircraft—ITP and reference aircraft data with horizontal velocity accuracies of at least 10 meters/second (m/s) (19.4 kts), 95 percent. A.5 ITP Description. To properly conduct an ITP, a qualified flightcrew uses ADS-B In avionics specifically certified to assist in verifying the initial conditions and a graphical display to monitor the relative position(s) of nearby aircraft. The procedure can only be conducted in airspace with appropriately trained ATC personnel, ITP-compatible automation, and approved ITP separation minima available. The following are the steps necessary to conduct an ITP: A.5.1 Flightcrew Verifies Initial Criteria. Using approved avionics, the ITP flightcrew verifies that their own-ship and the reference aircraft meet initial qualifying criteria. The onboard ITP avionics indicate to the flightcrew whether all initiation criteria are satisfied. A.5.2 Flightcrew Requests ITP. If the criteria are satisfied, the flightcrew requests the ITP clearance using the appropriate phraseology. Direct Controller Pilot Communication (DCPC) ensures unambiguous communication of the ITP request and ATC clearance. Currently, only Controller-Pilot Data Link Communication (CPDLC) is being used in locations where ITP is approved. Preformatted messages for requesting and approving ITP have been developed; however, not all aircraft have implemented them. In aircraft that do not have preformatted messages, flightcrews use standardized free text messages as described in Table A-2, Flightcrew Standardized Free Text Controller-Pilot Data Link Communication Message Set for In-Trail Procedure, and Table A-3, Controller Free Text Controller-Pilot Data Link Communication Message Set for In-Trail Procedure, until further notice. It is essential that the correct message elements be included in the correct format to allow the controller or automation system to properly evaluate the request. Improperly formatted or incomplete requests may be denied. Note: ATC will not issue an ITP clearance to any aircraft unless that aircraft has initiated a proper request. ### Page 36 Appendix A A-6 A.5.3 Controller Issues Clearance. Upon receipt of an ITP request, the controller: 1. Confirms the ITP aircraft and the reference aircraft are on the same track. a. Same-track criteria are not the same as the similar-track criteria, which are checked by the ITP aircraft flightcrew. b. Same-track includes the concept of similar-track (i.e., ITP aircraft and reference aircraft are traveling in the same direction with less than a 45-degree relative track angle between the aircraft), but also includes a check on whether or not the lateral protection areas overlap (e.g., lateral separation cannot be applied). This check can only be done by the controller who knows what separation standard is being applied between the aircraft. 2. Confirms that no more than two reference aircraft have been identified in the request and are identified correctly; that is, that the Aircraft Identification (ACID) of each reference aircraft in the ITP request exactly matches the corresponding aircraft’s filed flight plan (FP). 3. Ensures both the ITP aircraft and reference aircraft are not maneuvering and not expected to maneuver during the ITP. Note: A change of course (only) to remain on the same route would not be considered a maneuver, provided the course change is less than 45 degrees and the aircraft remain in a same track configuration. 4. Verifies that the closing Mach differential is no greater than 0.06 Mach. 5. Verifies that there are no conflicts at the requested altitude. 6. If appropriate, issues an ITP clearance. A.5.4 Flightcrew Reassesses Criteria. Upon receiving the ITP clearance, the flightcrew confirms that all criteria are still satisfied. If the criteria are not satisfied or there has been a loss of traffic information, the flightcrew immediately rejects the ATC clearance and terminates the maneuver. Additionally, if the FL, reference aircraft, or type of maneuver (ITP versus standard FL change) does not exactly match their request or if the flightcrew receives an ITP clearance without requesting one, they will not perform the maneuver and should verify with ATC to confirm the clearance. A.5.5 Flightcrew Executes ITP. If the criteria are still met, the flightcrew accepts the clearance and begins the requested climb or descent without delay. While executing the maneuver, the flightcrew is expected to maintain their flight-planned route, assigned Mach number (or current Mach, if none is assigned), and minimum Vertical Speed (VS) of 300 fpm and ensure they execute only the maneuver for which they have been cleared. The maneuver is complete once the flightcrew reports to ATC that they have reached the new FL. Note: Once the ITP maneuver has been initiated, it should be completed, and the aircraft not returned to the initial altitude. Should reference aircraft data be lost or ITP display fail during the maneuver, the flightcrew should continue the maneuver to the assigned altitude using the appropriate Mach number and ### Page 37 Appendix A A-7 300 fpm minimum VS. Upon completion of the maneuver, notify ATC of the ITP data loss. A.5.6 Approved ITP Variations. An ITP can be conducted with a maximum of two reference aircraft. The procedure design does not allow the reference aircraft to be more than 2,000 feet of altitude above or below the ITP aircraft, but there is no limit on the amount of altitude change the ITP aircraft may request. The reference aircraft both may be behind or ahead of the ITP aircraft or one may be ahead and one behind. Figure A-4 depicts the approved ITP variations. Figure A-4. In-Trail Procedure Climb/Descent Variations A .5.7 Contingency Procedures. The ITP maneuver has been extensively tested both in flight and in computer simulations with consideration given to a variety of environmental and aircraft performance factors. A temporary breach of the 10 NM ITP distance does not constitute an inherently unsafe procedure and should not be the sole factor when considering abandoning the procedure. No new contingency procedures are prescribed for ITP. If, in the pilot’s judgment, the ITP maneuver (i.e., reaching the newly assigned altitude) cannot be successfully completed once the climb or descent has been initiated, they will: 1. Contact ATC and request an alternative clearance as soon as practicable given flightcrew workload and flight conditions. 2. Inform ATC of any action the flightcrew is taking or requesting. Because of the many variables, the CPDLC message should be in the “free text” format. 3. Comply with regional contingency procedures appropriate to the circumstances, or as listed in ICAO Doc 4444, Section 15.2, Special Procedures for In-Flight Contingencies in Oceanic Airspace. ### Page 38 Appendix A A-8 A.5.8 ITP Distance. Except when one aircraft is directly in trail of another, the ITP distance is not the same as the direct line distance between those two aircraft. (See paragraph A.3, ITP Terminology, for the exact description and Figure A-2 for examples.) Since the ITP software is designed to calculate and display ITP distance information, extensive training on the subject is not necessary. However, it is important to emphasize that range and ITP distance are different. Consequently, a lack of understanding could lead the flightcrew to misidentify the correct reference aircraft when requesting an ITP clearance. Training should include examples of the various ITP distance geometries depicted in Figure A-2. A.5.8.1 Lateral Traffic Filters. Some ITP avionics incorporate a lateral traffic filter. The function of the traffic filter is to eliminate any targets beyond a predetermined lateral distance of own-ship’s track from consideration as a potential reference aircraft. This is intended to prevent the flightcrew from misidentifying incorrect reference aircraft during their ITP request. The filter is most useful when in an organized track environment or where traffic may be on a parallel user-preferred route. Incorrect use may result in denied ITP requests. Training should include recommended technique for its use. A.5.8.2 ITP Initiation Criteria. Traffic displayed as an ADS-B In target might not be presented as a valid ITP reference aircraft because it does not meet one or more ITP initiation criteria. Some of the criteria, such as position accuracy, are not displayed to the flightcrew. Training should include a discussion of the initiation criteria, which criteria are known to the flightcrew, and examples of when a displayed ADS-B In target is not an eligible ITP reference aircraft. See Table A-1 for ITP initiation criteria. A.6 Authorization to Conduct ITP. FAA authorization is required for all U.S. aircraft operators to conduct ITP operations using ADS-B In (14 CFR § 119.49(a)(5)). This appendix provides guidance to operators on the process for requesting issuance of this authorization, including guidance on the documentation that should be submitted. Note 1: For FAA authorization, refer to FAA Order 8900.1, Volume 3, Chapter 18, Section 3, Operations Specification (OpSpec)/Management Specification (MSpec)/Letter of Authorization (LOA) A354, Automatic Dependent Surveillance-Broadcast (ADS-B) In-Trail Procedure (ITP). Note 2: Operators may already hold other ADS-B In authorizations. There is no need to submit documentation for an ITP authorization if that documentation has already been submitted for previous ADS-B In authorizations. The ITP application may include references to those duplicate documents instead. A.6.1 Initial Request for Authorization. U.S. aircraft operators seeking to conduct ITP should first contact their assigned FAA office to indicate their intent. At the time of the operator’s initial request, the FAA will provide the operator with an ITP Application Checklist, which should be completed with attached supporting documents. ### Page 39 Appendix A A-9 A.6.2 Documentation to Submit With Formal Proposal. A.6.2.1 Documentation Guidance. The following section provides general guidance on the documentation required for submission of a formal ITP proposal. At the discretion of the operator’s assigned principal inspector (PI), additional information may be required based on any unique aspects of their specific operation. The operator must submit a letter of request for issuance of authorization to the assigned PI. The letter of request should include the following information: • Type of aircraft (make, model, and series (M/M/S)). • ADS-B equipment complies with Technical Standard Order (TSO)-C195b, Avionics Supporting Automatic Dependent Surveillance – Broadcast (ADS-B) Aircraft Surveillance Applications (ASA), or later revision, or as approved for ITP by the Administrator. • Installation has been completed following guidance in AC 20-172, Airworthiness Approval for ADS-B In Systems and Applications, or other acceptable means. • Manufacturer’s name of the ADS-B In software. • Proposed region(s) of operation (not applicable to 14 CFR part 91 operations). Note: The guidance contained in paragraph A.6.2 will also be annotated on the ITP Using ADS-B In Application Checklist provided to the operator by the applicable FAA office. A.6.2.2 Airplane Flight Manual (AFM) Compliance Documentation. Operators submit documentation that demonstrates that their aircraft have an ADS-B In system that meets the performance standards of TSO-C195b or later revision, or as approved for ITP by the Administrator. A.6.2.3 Proposed Operations Area. Authorizations to conduct ITP are limited to specific regions of the world where the ANSP offers ITP and those procedures are determined to be acceptable to the Administrator. Routes or airspace where ITP may be authorized will be published in Aeronautical Information Publications (AIP). Include in your request a description, by flight information region (FIR) and ANSP, of the operational areas where you propose to conduct ITP. If the operator holds an OpSpec/MSpec B050, Authorized Areas of En Route Operations, Limitations, and Provisions, authorization, submit a draft OpSpec/MSpec B050 that includes the operational areas where you propose to conduct ITP, including applicable notes. A.6.2.4 Operational Procedures. As applicable, company manuals should address any ITP-specific guidance from the Air Traffic Service Provider (ATSP) of the proposed region(s) of operation. ### Page 40 Appendix A A-10 A.6.2.5 Operation Manuals and Checklists. The certificate holder (CH)/operator/program manager (as applicable) should submit information (e.g., Airplane Operations Manual (AOM) bulletin or equivalent) to the flightcrews describing ADS-B, to include: • ITP system description; • Normal procedures; • En route procedures using ITP; • Communications; and • Non-normal or contingency procedures. A.6.2.6 Maintenance. See Appendix C, ADS-B In Operations—Aircraft Qualification and Maintenance, for applicable maintenance guidance. A.6.2.7 Revision of Minimum Equipment List (MEL). See Appendix C for guidance on the necessary MEL documents to be submitted for authorization of ITP. A.6.2.8 Pilot Training. Submit applicable portions of proposed ITP-specific pilot training material and include a description of the methods used to conduct, evaluate, and manage the training. The following contains the recommended information to be included in pilot training material: 1. General understanding of ADS-B In operations (i.e., technology, capabilities, and limitations). 2. ITP system operation, including: • Normal procedures; • Non-normal and/or contingency procedures; • ITP flight planning considerations; • ITP dispatch considerations (as applicable); • MEL considerations (as applicable); • ITP terminology, including proper formulation of a CPDLC ITP request/clearance; and • ITP equipment limitations. 3. Explanation of ITP distance as distinct from aircraft range, using select scenario-based examples (see Figure A-2 for ITP distance geometries): • ITP directly in trail of a reference aircraft; • ITP aircraft on a crossing track of reference aircraft—diverging; ### Page 41 Appendix A A-11 • ITP aircraft on a crossing track of reference aircraft—converging; and • ITP aircraft on a parallel track of reference aircraft. A.6.2.9 Dispatch/Flight Follower Training. Submit applicable portions of proposed ITP-specific dispatch/flight planning training material, to include any appropriate updates to the dispatch operations manual, or equivalent, as well as a description of the methods used to conduct, evaluate, and manage training. The following contains the recommended information to be included in dispatch/flight planning training material: 1. General understanding of ADS-B In operations; 2. Dispatch of aircraft with the ITP system unserviceable; 3. How flight planning codes are affected with ADS-B unserviceable; 4. Flight planning, fuel loading, and route change procedures associated with ITP operations; 5. Equipment needed to conduct ITP; and 6. Approved ITP routes and airspace. Note: Dispatch/flight follower training is not required for 14 CFR part 91 operations. However, as the pilot is responsible for flight planning, the pilot should consider these items prior to flight. ### Page 42 Appendix A A-12 Table A-1. In-Trail Procedure Initiation/Maneuver Criteria (Reference RTCA DO-312 Supplement) In-Trail Procedure (ITP) Speed/Distance Criteria ITP Distance ≥ 15 nautical miles (NM) and Closing Groundspeed (GS) Differential ≤ 20 knots (kts) ITP Distance ≥ 20 NM and Closing GS Differential ≤ 30 kts Relative Altitude Criteria Difference in altitude between ITP and Reference Aircraft is less than or equal to 2,000 feet Similar Track Criteria Difference in track angles between ITP and Reference Aircraft is less than ±45 degrees Position Accuracy for ITP and Reference Aircraft ITP and Reference Aircraft data with horizontal position accuracies of at least 0.5 NM (95%) Position Integrity for ITP and Reference Aircraft ITP and Reference Aircraft data with horizontal position integrity bounds of 1.0 NM at 1×10E-05 Velocity Accuracy for ITP and Reference Aircraft ITP and Reference Aircraft data with horizontal velocity accuracies of at least 10 meters/second (m/s) (19.4 kts), 95% Closing Mach Differential (Air Traffic Control (ATC) Crosscheck) Closing Mach Differential is less than or equal to 0.06 Mach ### Page 43 Appendix A A-13 Table A-2. Flightcrew Standardized Free Text Controller-Pilot Data Link Communication Message Set for In-Trail Procedure In-Trail Procedure (ITP) Type (number and relative position of reference aircraft) FREE TEXT Message Element Content 1 reference aircraft (ahead) “ITP [Distance] BEHIND [Aircraft flight identification (FLT ID)]” 1 reference aircraft (behind) “ITP [Distance] AHEAD OF [Aircraft FLT ID]” 2 reference aircraft (both ahead) “ITP [Distance] BEHIND [Aircraft FLT ID] AND [Distance] BEHIND [Aircraft FLT ID]” 2 reference aircraft (both behind) “ITP [Distance] AHEAD OF [Aircraft FLT ID] AND [Distance] AHEAD OF [Aircraft FLT ID]” 2 reference aircraft (one ahead and one behind) “ITP [Distance] BEHIND [Aircraft FLT ID] AND [Distance] AHEAD OF [Aircraft FLT ID]” To request an ITP climb or descent, the flightcrew will send a Controller-Pilot Data Link Communication (CPDLC) REQUEST CLIMB TO [altitude] or REQUEST DESCENT TO [altitude] message, as applicable, with the following verbiage added to FREE TEXT as listed in Table A-2: Example of ITP request message: REQUEST CLIMB TO FL360 ITP 25 NM BEHIND SIA228 AND 21 NM AHEAD OF AFR008. Note: This standardized free text message set will be used until an appropriate message set is implemented. ### Page 44 Appendix A A-14 Table A-3. Controller Free Text Controller-Pilot Data Link Communication Message Set for In-Trail Procedure In-Trail Procedure (ITP) Type (number and relative position of reference aircraft) FREE TEXT Message Element Content 1 reference aircraft (ahead) “ITP BEHIND [Aircraft flight identification (FLT ID)]” 1 reference aircraft (behind) “ITP AHEAD OF [Aircraft FLT ID]” 2 reference aircraft (both ahead) “ITP BEHIND [Aircraft FLT ID] AND BEHIND [Aircraft FLT ID]” 2 reference aircraft (both behind) “ITP AHEAD OF [Aircraft FLT ID] AND AHEAD OF [Aircraft FLT ID]” 2 reference aircraft (one ahead and one behind) “ITP BEHIND [Aircraft FLT ID] AND AHEAD OF [Aircraft FLT ID]” To grant an ITP request, the controller will send an uplink message containing CLIMB TO AND MAINTAIN [altitude] or DESCEND TO AND MAINTAIN [altitude] containing the text in Table A-3: Example of ITP clearance message: ITP BEHIND SIA228 AND AHEAD OF AFR008 CLIMB TO FL360 REPORT LEVEL FL360. Note 1: The controller should never issue an ITP clearance unless one has been requested by a flightcrew. Note 2: This standardized free text message set will be used until an appropriate message set is implemented. ### Page 45 Appendix B B-1 APPENDIX B. CAVS USING ADS-B IN B.1 Purpose. This appendix describes Cockpit Display of Traffic Information (CDTI) Assisted Visual Separation (CAVS) and provides guidance to operators seeking FAA authorization to conduct CAVS operations. B.2 Background. When a flightcrew accepts responsibility to maintain visual separation from another aircraft, they should maintain constant visual surveillance of that aircraft and notify air traffic control (ATC) if they can no longer do so. Additionally, the flightcrew accepts the responsibility for wake turbulence separation from that aircraft. Though the weather must be visual meteorological conditions (VMC) pursuant to CAVS authorization, other environmental conditions may prevent them from maintaining constant visual surveillance of the traffic, such as when the traffic is landing toward a rising or setting sun. Additionally, distances and closure rate to an aircraft directly ahead can be difficult to judge, such that avoiding wake turbulence and getting too close to the traffic can be difficult. B.3 CAVS Concept. CAVS is an ADS-B In application that assists the flightcrew in maintaining separation from ADS-B Out-equipped aircraft during visual separation. Currently, CAVS authorization is only for the approach phase of flight when cleared by ATC to maintain visual separation from specific traffic. Because of the accuracy and integrity of displayed traffic on ADS-B In systems approved for CAVS, CAVS information may be used as a substitute for continuous visual observation of traffic-to-follow (TTF) under specified conditions. CAVS does not relieve the pilot of the responsibility to see and avoid other aircraft. ATC maintains separation responsibility from all other aircraft and for the orderly flow of traffic to the runway. Currently, there is no new phraseology associated with CAVS and approved for the use of CAVS. ATC will be unaware that a flightcrew is using CAVS. CDTI does not replace any traffic advisories (TA) and/or Resolution Advisories (RA) provided by the aircraft’s Airborne Collision Avoidance System (ACAS). RA response is still based on the ACAS display and approved procedures. Note: See Appendix G, CDTI Assisted Separation on Approach, for a description of CDTI Assisted Separation on Approach (CAS-A). B.4 CAVS Arrivals. Traffic information from the CDTI is used to augment out-the-window (OTW) visual contact with an aircraft a flightcrew is assigned to follow. This will enable them to accept separation responsibility from that aircraft. Once the flightcrew has visually acquired and accepted a visual approach clearance behind TTF, the pilot may use the lead aircraft traffic information on the CDTI as a means for maintaining separation while performing a visual approach. As done today with a visual approach clearance, no specific spacing assignments will be made by ATC. The procedure can be conducted behind all weight classes except when the lead aircraft is a super. B.5 CAVS Description. Flightcrews are reminded that CAVS is a visual separation procedure. If at any time the traffic information provided by CAVS equipment becomes unreliable, inoperative, or distracting, its use should be discontinued immediately. ### Page 46 Appendix B B-2 Note 1: Although aircraft call signs are displayed on the CDTI, flightcrews should not use the call sign or Aircraft Identification (ACID) (flight identification (FLT ID)) of observed traffic in radio communications, as this could create confusion for both ATC and flightcrews monitoring the frequency. Note 2: Flightcrews are not relieved of their duty to see and avoid. Note 3: CAVS is currently restricted to maintaining visual separation from aircraft approaching the same landing runway. B.5.1 CAVS Alerting. Installations compliant with Technical Standard Order (TSO)-C195b, Avionics Supporting Automatic Dependent Surveillance – Broadcast (ADS-B) Aircraft Surveillance Applications (ASA), or later revision, incorporate two unique alerting features: a caution level minimum range alert and an advisory level selectable range indication. B.5.1.1 The selectable range indication alert is used to advise the flightcrew that the CAVS aircraft is at a predetermined range from the TTF. The range indication is set in accordance with individual established company procedures and is intended to assist the flightcrew in maintaining a safe distance from the TTF. B.5.1.2 The caution level minimum range alert is activated when the range to the TTF is less than 0.42 nautical miles (NM), and can be issued on traffic that is within 1.4 NM under certain conditions. This alert cannot be modified by the flightcrew and indicates that, due to uncertainty in the ADS-B positions at such close ranges, the CDTI cannot safely be used to determine the position of the TTF. B.5.2 Normal Procedures. CAVS normal procedures are as follows: 1. ATC points out TTF to the flightcrew of CAVS-equipped aircraft. 2. The CAVS flightcrew visually locates the traffic OTW and reports this to ATC. 3. ATC issues a clearance to “maintain visual separation” from the TTF. 4. If the TTF is broadcasting usable ADS-B Out information, the CAVS flightcrew correlates the TTF as seen OTW, with the traffic symbol of the TTF aircraft displayed on their aircraft’s CDTI and any information provided via ADS-B. 5. Once the flightcrew has correctly correlated the TTF on the CDTI, they designate the TTF target on the CDTI, and the avionics display the distance and groundspeed (GS) differential between TTF and own-ship. If CAVS is equipped with a selectable range indication alert, the flightcrew may set it in accordance with company procedures if it has not already been set. 6. Aided by this information, the CAVS flightcrew can more easily maintain visual contact with the TTF and manage their distance and closure. 7. The CAVS aircraft maintains VMC at all times. However, if the flightcrew should lose OTW contact with the TTF, the approach may continue using the CDTI (and ### Page 47 Appendix B B-3 ADS-B Guidance Display (AGD), if one is installed) to maintain visual separation using the CAVS information alone. B.5.3 Maneuver Termination. CAVS is intended to assist the flightcrew in maintaining pilot-applied visual separation. The loss of CAVS information does not itself require discontinuing visual separation, provided OTW visual contact with the TTF and safe separation can be maintained. Discontinue using CAVS as a substitute for OTW visual contact under any of the following conditions: 1. The flightcrew is unable to maintain VMC. 2. AGD (if installed) fails and OTW visual contact cannot be maintained. 3. AGD (if installed) information conflicts with the CDTI information to the extent that it becomes a distraction, is confusing to the pilots, or raises a concern about the safety of the procedure. 4. Sustained loss of ADS-B data quality and/or integrity as indicated to the pilot via the displays. 5. The caution level minimum range alert is activated. 6. If the flightcrew is unable to maintain a safe distance for any reason, they must immediately advise ATC and request further clearance. B.6 CAVS System. The CAVS authorization requires an aircraft to have an installed ADS-B In system that meets the standards of TSO-C195b or later revision, or a system approved by the Administrator intended for use in CAVS. For guidance on the installation of ADS-B Out equipment, refer to AC 20-165, Airworthiness Approval of Automatic Dependent Surveillance - Broadcast OUT Systems, and AC 20-172, Airworthiness Approval for ADS-B In Systems and Applications. B.7 Authorization to Conduct CAVS. FAA authorization is required for all U.S. aircraft operators to conduct CAVS operations using ADS-B In (14 CFR § 119.49(a)(5)). This appendix provides guidance to operators on the process for requesting issuance of this authorization, including guidance on the documentation that should be submitted. Note 1: For FAA authorization, refer to FAA Order 8900.1, Volume 3, Chapter 18, Section 3, Operations Specification (OpSpec)/Management Specification (MSpec)/Letter of Authorization (LOA) A355, Automatic Dependent Surveillance-Broadcast (ADS-B) In Operations. Note 2: Operators may already hold other ADS-B In authorizations. There is no need to submit documentation for a CAVS authorization if that documentation has already been submitted for previous ADS-B In authorizations. The CAVS application may include references to those duplicate documents instead. B.7.1 Initial Request for Authorization. U.S. aircraft operators seeking to conduct CAVS should first contact their assigned FAA office to indicate their intent. At the time of the ### Page 48 Appendix B B-4 operator’s initial request, the FAA will provide the operator with a CAVS Application Checklist, which should be completed with attached supporting documents. B.7.2 Documentation to Submit With Formal Request. B.7.2.1 Documentation Guidance. This section describes the documentation required for submission of a formal CAVS proposal. The operator’s assigned principal inspector (PI) may ask for additional information based on any unique aspects of their specific operation. The operator should submit a letter of request for issuance of authorization to the assigned PI. The letter of request should include the following information: • Type of aircraft (make, model, and series (M/M/S)). • List of aircraft registration numbers (N-number) associated with the request for authorization. • ADS-B equipment complies with TSO-C195b or later revision, or as approved for CAVS by the Administrator. • Installation has been completed following guidance contained in AC 20-172, or other acceptable means. • Name of the ADS-B In (CAVS) software manufacturer and applicable software version(s). B.7.2.2 Airplane Flight Manual (AFM) Compliance Documentation. Operators will submit documentation that demonstrates applicable aircraft have an ADS-B In system that meets the performance standards of TSO-C195b or later revision, or as otherwise approved by the Administrator, for CAVS operations. B.7.2.3 Operation Manuals and Checklists. The certificate holder (CH)/operator/program manager (as applicable) should submit information (e.g., Airplane Operations Manual (AOM) bulletin or equivalent) to the flightcrews describing ADS-B, to include: • CAVS system description; • Normal procedures; and • Non-normal or contingency procedures. B.7.2.4 Maintenance. See Appendix C, ADS-B In Operations—Aircraft Qualification and Maintenance, for applicable maintenance guidance. B.7.2.5 Revision of Minimum Equipment List (MEL). See Appendix C for guidance on the necessary MEL documents to be submitted for authorization of CAVS. ### Page 49 Appendix B B-5 B.7.2.6 Pilot Training. Submit applicable portions of proposed CAVS-specific pilot training material and include a description of the methods used to conduct, evaluate, and manage the training. The CAVS pilot training should include: 1. ADS-B Out/In system overview (if not previously addressed with another ADS-B application). 2. ADS-B CAVS system operations. 3. CAVS normal procedures: • Visual separation procedures. • Speed management. • Assessing closure rates. • Wake turbulence avoidance. • Weather minimums. • Use of and response to the selectable CAVS range alert. • Crew coordination during CAVS. 4. CAVS MEL procedures (as applicable). 5. CAVS equipment limitations. 6. CDTI interface. 7. Contingency procedures. ### Page 50 Appendix C C-1 APPENDIX C. ADS-B IN OPERATIONS—AIRCRAFT QUALIFICATION AND MAINTENANCE C.1 Purpose. This appendix provides guidance on aircraft qualification, maintenance, and maintenance personnel training associated with authorization of ADS-B In operations. C.2 Applicability. The ADS-B In aircraft qualification and maintenance guidance contained herein applies to operations conducted under 14 CFR parts 91, 91 subpart K (14 CFR part 91K), 121, 125 (including 14 CFR part 125 Letter of Deviation Authority (LODA)), 129, and 135. Title 14 CFR part 91 operators (excluding 14 CFR part 91K operators) should comply with the guidance contained in this appendix. Operators conducting operations under 14 CFR parts 91K, 121, 125 (including 14 CFR part 125 LODA), 129, and 135 should address all aspects of the guidance contained in this appendix when submitting requests for authorization of ADS-B In operations. C.3 Aircraft Qualification. C.3.1 ADS-B In systems must meet the standards of the appropriate Technical Standard Order (TSO)-C195b, Avionics Supporting Automatic Dependent Surveillance – Broadcast (ADS-B) Aircraft Surveillance Applications (ASA), or later revision, for authorization. Guidance on the installation of ADS-B Out equipment can be found in AC 20-165, Airworthiness Approval of Automatic Dependent Surveillance - Broadcast OUT Systems. Guidance on the installation of ADS-B In systems can be found in AC 20-172, Airworthiness Approval for ADS-B In Systems and Applications. C.3.2 Applications submitted to the FAA for authorization to conduct ADS-B In operations should contain the following documentation to demonstrate aircraft qualification: 1. Applicable ADS-B In airworthiness documentation in the form of an aircraft type certificate (TC), amended TC, or Supplemental Type Certificate (STC). 2. ADS-B In avionics manufacturer’s instructions for continued airworthiness (ICA), as accepted by the FAA. 3. Proposed minimum equipment list (MEL) revisions, if applicable, listing all limitations and procedures associated with the dispatch of aircraft with the ADS-B In system inoperative. C.4 Maintenance. C.4.1 Maintenance of ADS-B In systems should comply with the guidance contained in this paragraph and must comply with applicable airworthiness regulations. Maintenance personnel should be familiar with the operator’s ADS-B In system maintenance procedures, their individual responsibilities with respect to those procedures, and the availability of any resources within or outside of the maintenance organization necessary to ensure the continued airworthiness of the ADS-B In system. ### Page 51 Appendix C C-2 C.4.2 Applications submitted for authorization to conduct ADS-B In operations under 14 CFR parts 91, 91K, 121, 125 (including 14 CFR part 125 LODA), 129, and 135 should include documentation that includes the following, as applicable: 1. The General Maintenance Manual (GMM) and, for 14 CFR part 125, the Policy and Procedures Manual (PPM) should incorporate the ADS-B In manufacturer’s ICA, as accepted by the FAA, and identify any special techniques, maintenance/inspection frequencies, and test equipment used to support the continued airworthiness of the system. 2. Indicate whether ADS-B In system maintenance is integrated into an existing approved maintenance program or is a separate program. 3. Identify the GMM or PPM revision and update procedures, if not previously approved. 4. Identify how maintenance personnel will be trained on the ADS-B In system and the method to record and maintain any associated qualifications. 5. Procedures for ADS-B In software installation, updates, evaluations, tests, and configuration control. 6. Procedures used to make modifications, additions, and changes to the ADS-B In system. 7. Procedures for ADS-B In discrepancy reporting and recording. 8. MEL and logbook procedures for deferral of the ADS-B In system or components of the system. 9. Notification procedures between maintenance control, engineering, flight operations, and dispatch (or equivalent) when the ADS-B In system is deferred. 10. Procedures to monitor and identify ADS-B In-equipped aircraft with chronic discrepancies and restrict the aircraft from ADS-B In operations until appropriate corrective action and verification tests have been performed. 11. Procedures for return to service of the ADS-B In system following routine/nonroutine maintenance or completion of corrective action on an aircraft flagged for chronic discrepancies. 12. Integration of ADS-B In maintenance into existing quality control (QC) and quality assurance (QA) programs, as applicable. C.5 Maintenance Personnel Training. C.5.1 General. This paragraph contains guidance on maintenance personnel training associated with ADS-B In operations. Operators should address this guidance, as applicable, in proposals submitted to the FAA for authorization to conduct ADS-B In operations. C.5.2 Maintenance Training. Maintenance personnel should be knowledgeable of the guidance contained in this AC and applicable regulations. Operator and contract maintenance personnel, including mechanics, maintenance controllers, avionics technicians, and ### Page 52 Appendix C C-3 inspection/QA personnel, should receive initial and recurrent training (as necessary) to establish and maintain an effective ADS-B In maintenance program. C.5.3 Application Submissions. Applications submitted for authorization to conduct ADS-B In operations should address the following: 1. Identify the person(s) responsible for ensuring ADS-B In maintenance and inspection personnel are properly trained, knowledgeable, and current in accordance with the GMM or PPM, as appropriate. 2. Identify how the ADS-B In training will be conducted (i.e., in-house or outside training provider). 3. Include policy and procedures that address any qualifications for ADS-B In maintenance and inspection personnel. 4. Identify the methods and techniques used to conduct initial and recurrent training (e.g., Instructor-Led Training (ILT), computer-based training (CBT), and on-the-job training (OJT)). 5. Identify the procedures used to record and maintain initial and recurrent ADS-B In training and qualifications. 6. Include maintenance and inspection training curriculum that addresses the following ADS-B In topics: • Operational overview; • Aircraft system overview; • Maintenance and inspection procedures; • Personnel training qualifications (as applicable); • MEL procedures; • Test equipment and use (as applicable); and • Return to service test procedures. ### Page 53 Appendix D D-1 APPENDIX D. DEFINITIONS The terms have the following meaning when used in this AC: D.1 Automatic Dependent Surveillance-Broadcast (ADS-B) Airspace. The airspace specified in 14 CFR § 91.225. D.2 Automatic Dependent Surveillance-Broadcast (ADS-B) Guidance Display (AGD). The AGD provides digital readouts and alerts of time-sensitive information located on the Cockpit Display of Traffic Information (CDTI). This is used primarily for installations where the CDTI is not installed in the forward field of view (FOV). D.3 Automatic Dependent Surveillance-Broadcast (ADS-B) In. ADS-B In is the receipt, processing, and display of ADS-B transmissions. ADS-B In is necessary to utilize ADS-B traffic and broadcast services (e.g., Flight Information Service-Broadcast (FIS-B) and Traffic Information Service-Broadcast (TIS-B)). D.4 Automatic Dependent Surveillance-Broadcast (ADS-B) Out. Transmission of an aircraft’s position, altitude, velocity, and other information to other aircraft and air traffic control (ATC) surveillance systems. D.5 Automatic Dependent Surveillance-Rebroadcast (ADS-R). ADS-R is a link-translation and rebroadcast function of the ADS-B ground system that allows both ADS-B frequencies (1090 megahertz (MHz) and 978 MHz) to share information. D.6 Cockpit Display of Traffic Information (CDTI). This is a generic display that provides the flightcrew with surveillance information about other aircraft, including position. Traffic information may be obtained from one or multiple sources, including ADS-B, Airborne Collision Avoidance System (ACAS), and TIS-B. The display of information may be hosted on an Electronic Flight Bag (EFB) or the aircraft’s integrated avionics suite. D.7 Cockpit Display of Traffic Information (CDTI) Assisted Separation on Approach (CAS-A). CAS-A is an operation that builds on the existing CDTI Assisted Visual Separation (CAVS) operation, as described in Appendix B, CAVS Using ADS-B In, and uses the same flight deck avionics as required for CAVS. CAS-A is initiated by the controller, who provides a CAS-A designation instruction that includes the flight identification (FLT ID) for the traffic-to-follow (TTF). The flightcrew identifies the TTF on the CDTI using the FLT ID provided by the controller (visual acquisition is not required). D.8 Cockpit Display of Traffic Information (CDTI) Assisted Visual Separation (CAVS). CAVS is an ADS-B In application that assists the flightcrew in maintaining visual separation from ADS-B Out-equipped aircraft. D.9 Extended Squitter (ES). ES is how ADS-B messages are transmitted from a Mode Select (Mode S) transponder. ES is a long message (e.g., format DF=17) that ### Page 54 Appendix D D-2 Mode S transponders transmit automatically, without interrogation by radar, to announce the own-ship aircraft’s presence to nearby ADS-B-equipped aircraft and ground stations. D.10 Flight Information Service-Broadcast (FIS-B). FIS-B is a ground broadcast service provided over the 978 MHz frequency Universal Access Transceiver (UAT) data link. The FAA FIS-B system provides pilots and flightcrews of properly equipped aircraft (ADS-B In) with a flight deck display of certain aviation weather and aeronautical information for advisory-only use. D.11 Flightcrew. One or more flight deck crewmembers required for the operation of the aircraft. D.12 Global Navigation Satellite System (GNSS). The generic term for a satellite navigation system, such as the Global Positioning System (GPS), that provides autonomous worldwide geospatial positioning and may include local or regional augmentations. D.13 Global Positioning System (GPS). GPS is a U.S. satellite-based radio navigation system that provides a global positioning service. The service provided by GPS for civil use is defined in the GPS Standard Positioning Service (SPS) Performance Standard. D.14 International Civil Aviation Organization (ICAO). A United Nations (UN) organization that is responsible for developing international standards and for recommending practices and procedures covering a variety of technical fields of aviation. D.15 International Civil Aviation Organization (ICAO) Aircraft Address (Mode S Code). Address assigned to each aircraft transponder and ADS-B transmitter during registration or change of registration. D.16 Interval Management (IM). IM is a set of procedures and capabilities designed to provide precise aircraft-to-aircraft spacing, and is suitable for use en route, on a terminal arrival, and final approach. D.17 In-Trail Procedure (ITP). An ITP is designed primarily for use in nonradar oceanic airspace to enable appropriately equipped ADS-B In aircraft to perform flight level (FL) changes previously unavailable with procedural separation minima applied. D.18 Mode A. One of a possible 4,096 identification codes that are transmitted from an aircraft transponder or ADS-B transmitter. The Mode A code is also known as the squawk code for the aircraft. The Mode A code is used in ATC for associating flight plans (FP) with surveillance data. D.19 Mode C. The encoded barometric altitude from an onboard pressure sensor is contained in the Mode C. This altitude information is transmitted by the aircraft transponder in response to an appropriate interrogation from a secondary radar system. The Mode C is used by ATC to determine the altitude of the reporting aircraft. D.20 Mode S. A Secondary Surveillance Radar (SSR) system that operates using addressed interrogation on 1030 MHz, and the transponder replies on 1090 MHz. Mode S systems ### Page 55 Appendix D D-3 interrogate for aircraft identity (Mode A code), altitude, and other aircraft-specific information. The aircraft transponder replies with the requested information. Mode S supports an ADS-B service known as 1090ES. D.21 Non-Performing Equipment (NPE). ADS-B Out-equipped aircraft operating contrary to 14 CFR § 91.225 and/or § 91.227. D.22 Position Source. The onboard avionics equipment that provides the latitude, longitude, geometric altitude, velocity, position and velocity accuracy metrics, and position integrity metric to the ADS-B transmitter. Additionally, the position source may provide the vertical rate parameters. Currently, only GPS, GPS with Wide Area Augmentation Systems (WAAS), and Aircraft-Based Augmentation System (ABAS) sensors tightly integrated with GPS are approved as position sources. D.23 Secondary Surveillance Radar (SSR). A radar sensor that listens to replies sent by transponders carried on onboard airborne targets. SSR sensors, in contrast to Primary Surveillance Radar (PSR) sensors, require the aircraft under surveillance to carry a transponder. D.24 Statement of Compliance (SOC). The SOC is a manufacturer-generated document that states the ADS-B equipment, when installed in accordance with the installation instructions, complies with all requirements of 14 CFR § 91.227, and with the performance requirements of the appropriate Technical Standard Order (TSO). D.25 Surveillance. Detection, tracking, characterization, and observation of aircraft, other vehicles, weather, and airspace status information and phenomena for the purposes of conducting flight operations in a safe and efficient manner. The primary purposes of traffic surveillance (as distinct from all surveillance functionality) are to control the flow of aircraft, to provide situational awareness for pilots and controllers, and to separate aircraft. D.26 Traffic Information Service-Broadcast (TIS-B). TIS-B is a ground broadcast service provided from an ADS-B ground system network over the UAT and 1090ES links that provides position, velocity, and other information on traffic that is detected by airport surface detection equipment (ASDE), SSR, or Wide Area Multilateration (WAM), but that is not transmitting an ADS-B position. In the United States, TIS-B service will always be deployed with the ADS-R service so that a complete traffic picture is provided for both nonequipped and alternate-link-equipped aircraft. D.27 Transponder. The airborne radar beacon receiver/transmitter portion of the ATC radar beacon system (ATCRBS) or Mode S system that automatically receives radio signals from interrogators and replies with specific reply information as requested. D.28 Universal Access Transceiver (UAT). UAT is a wideband multipurpose data link intended to operate globally on a single channel with a channel signaling rate of just over 1 megabit per second (Mbps). By design, UAT supports multiple broadcast services, including FIS-B and TIS-B, in addition to ADS-B. ### Page 56 Appendix D D-4 D.29 Visual Meteorological Conditions (VMC). Weather conditions in which pilots have sufficient visibility to fly the aircraft while maintaining visual separation from terrain and other aircraft. The exact requirements vary by class of airspace (e.g., Class B airspace: 3 statute miles (sm) visibility, clear of clouds). ### Page 57 Appendix E E-1 APPENDIX E. RELATED REGULATIONS AND READING MATERIAL E.1 Related 14 CFR Parts. You can find the Code of Federal Regulations (CFR) online at https://www.ecfr.gov. 1. Section 1.1, General Definitions. 2. Section 21.50, Instructions for Continued Airworthiness and Manufacturer’s Maintenance Manuals Having Airworthiness Limitations Sections. 3. Part 61, Certification: Pilots, Flight Instructors, and Ground Instructors. 4. Section 91.1, Applicability. 5. Section 91.103, Preflight Action. 6. Section 91.130, Operations in Class C Airspace. 7. Section 91.131, Operations in Class B Airspace. 8. Section 91.135, Operations in Class A Airspace. 9. Section 91.217, Data Correspondence Between Automatically Reported Pressure Altitude Data and the Pilot’s Altitude Reference. 10. Section 91.225, Automatic Dependent Surveillance-Broadcast (ADS-B) Out Equipment and Use. 11. Section 91.227, Automatic Dependent Surveillance-Broadcast (ADS-B) Out Equipment Performance Requirements. 12. Part 91 Subpart K (Part 91K), Fractional Ownership Operations. 13. Part 121, Operating Requirements: Domestic, Flag, and Supplemental Operations. 14. Part 125, Certification and Operations: Aircraft Having a Seating Capacity of 20 or More Passengers or a Maximum Payload Capacity of 6,000 Pounds or More; and Rules Governing Persons On Board Such Aircraft. 15. Part 133, Rotorcraft External-Load Operations. 16. Part 135, Operating Requirements: Commuter and On Demand Operations and Rules Governing Persons On Board Such Aircraft. 17. Part 137, Agricultural Aircraft Operations. E.2 Related Reading Materials (current editions). • You can find this and other ACs on the FAA’s website at https://www.faa.gov/regulat ions_policies/advisory_circulars or on the Dynamic Regulatory System (DRS) at https://drs.faa.gov. ### Page 58 Appendix E E-2 • Inspectors and air carriers can access FAA Order 8900.1, Flight Standards Information Management System, on DRS. Operators and the public can find this order on the FAA’s website at https://www.faa.gov/regulations_policies/orders_notic es and DRS. • You can find a current list of Technical Standard Orders (TSO) on DRS. E.2.1 FAA Guidance Material. 1. AC 20-165, Airworthiness Approval of Automatic Dependent Surveillance - Broadcast OUT Systems. 2. AC 20-172, Airworthiness Approval for ADS-B In Systems and Applications. 3. FAA Order 8900.1, Volume 3, Chapter 18, Section 3, Operations Specification (OpSpec)/Management Specification (MSpec)/Letter of Authorization (LOA) A354, Automatic Dependent Surveillance-Broadcast (ADS-B) In-Trail Procedure (ITP). 4. Aeronautical Information Manual (AIM), Paragraph 4-5-7, Automatic Dependent Surveillance-Broadcast (ADS-B) Services, through Paragraph 4-5-10, Automatic Dependent Surveillance-Rebroadcast (ADS-R). 5. Surveillance and Broadcast Services Description Document (SRT-047). E.2.2 FAA TSOs (edition listed below or later revision). 1. TSO-C129a, Airborne Supplemental Navigation Equipment Using the Global Positioning System (GPS). 2. TSO-C145c, Airborne Navigation Sensors Using the Global Positioning System Augmented by the Satellite Based Augmentation System (SBAS). 3. TSO-C146c, Stand-Alone Airborne Navigation Equipment Using the Global Positioning System Augmented by the Satellite Based Augmentation System (SBAS). 4. TSO-C154c, Universal Access Transceiver (UAT) Automatic Dependent Surveillance-Broadcast (ADS-B) Equipment Operating on Frequency of 978 MHz. 5. TSO-C157a, Aircraft Flight Information Services-Broadcast (FIS-B) Data Link Systems and Equipment. 6. TSO-C166b, Extended Squitter Automatic Dependent Surveillance - Broadcast (ADS-B) and Traffic Information Service - Broadcast (TIS-B) Equipment Operating on the Radio Frequency of 1090 Megahertz (MHz). 7. TSO-C195b, Avionics Supporting Automatic Dependent Surveillance – Broadcast (ADS-B) Aircraft Surveillance Applications (ASA). 8. TSO-C196a, Airborne Supplemental Navigation Sensors for Global Positioning System Equipment Using Aircraft-Based Augmentation. E.2.3 RTCA, Inc. Documents. You can find the most recent editions of RTCA documents available for purchase at https://my.rtca.org/nc__store. ### Page 59 Appendix E E-3 1. RTCA DO-260B, Minimum Operational Performance Standards for 1090 MHz Extended Squitter Automatic Dependent Surveillance - Broadcast (ADS-B) and Traffic Information Services - Broadcast (TIS-B). 2. RTCA DO-282, Minimum Operational Performance Standards for Universal Access Transceiver (UAT) Automatic Dependent Surveillance - Broadcast (ADS-B). 3. RTCA DO-312 Supplement, Safety, Performance and Interoperability Requirements Document for the In Trail Procedure in Oceanic Airspace (ATSA-ITP) Application. 4. RTCA DO-317B, Minimum Operational Performance Standards (MOPS) for Aircraft Surveillance Applications (ASA) System. 5. RTCA DO-328B, Safety, Performance and Interoperability Requirements Documents for Airborne Space – Flight Deck Interval Management (ASPA-FIM). 6. RTCA DO-354, Safety and Performance Requirements Document for CDTI Assisted Visual Separation (CAVS). 7. RTCA DO-361A, Minimum Operational Performance Standards (MOPS) for Flight-Deck Interval Management (FIM). E.3 European Union Aviation Safety Agency (EASA) Publications (current editions). 1. EASA Acceptable Means of Compliance (AMC) 20-24, Certification Considerations for the Enhanced ATS in Non-Radar Areas Using ADS-B Surveillance (ADS-B-NRA) Application via 1090 MHz Extended Squitter. 2. EASA Certification Specifications and Acceptable Means of Compliance for Airborne Communications, Navigation and Surveillance (CS-ACNS). ### Page 60 Appendix F F-1 APPENDIX F. INTERVAL MANAGEMENT CONTENTS Paragraph Page F.1 Purpose … F-3 F.2 Background … F-3 F.3 IM Description … F-3 F.3.1 IM Description—Ground Component … F-3 F.3.2 IM Description—Airborne Component … F-3 F.3.3 Notional Phraseology … F-4 F.3.4 Early FIM Avionics … F-4 F.4 IM Terminology … F-4 F.4.1 Assigned Spacing Goal (ASG) … F-4 F.4.2 Cross Point (CP) … F-4 F.4.3 Designated Traffic … F-4 F.4.4 Flight-Deck Interval Management (FIM) Avionics … F-4 F.4.5 Flight Identification (FLT ID) … F-5 F.4.6 Interval Management (IM) Aircraft … F-5 F.4.7 Interval Management (IM) Clearance Type … F-5 F.4.8 Interval Management (IM) Path Monitoring … F-5 F.4.9 Interval Management (IM) Speed … F-5 F.4.10 Interval Management (IM) Speed Compliance Monitoring … F-5 F.4.11 Planned Cancellation Point (PCP) … F-5 F.4.12 Selected Traffic … F-5 F.5 IM Clearance Types Described … F-5 F.5.1 Clearance Type Format … F-6 F.5.2 Maintain Current Spacing … F-6 F.5.3 Capture Then Maintain … F-7 F.5.4 Achieve-by Then Maintain (“Cross”) … F-7 F.5.5 Final Approach Spacing … F-8 F.5.6 IM Suspend … F-8 F.5.7 SafeRoute+ Differences … F-8 F.5.7.1 Maintain Current Spacing and Capture Then Maintain … F-8 ### Page 61 Appendix F F-2 F.5.7.2 Achieve-by Then Maintain … F-9 F.5.7.3 No IM Suspend … F-9 F.6 IM Procedure … F-9 F.6.1 ATC Identifies IM Pair … F-9 F.6.2 ATC Checks Feasibility … F-9 F.6.3 ATC Issues IM Clearance … F-9 F.6.4 IM Flightcrew Reads Back Clearance … F-10 F.6.5 IM Flightcrew Verifies Lead Aircraft … F-10 F.6.5.1 FLT ID Verification … F-10 F.6.6 FIM Avionics Internal Check … F-10 F.6.7 IM Flightcrew Evaluates IM Speed … F-10 F.6.7.1 Rejected Clearance … F-10 F.6.7.2 Accepted Clearance … F-10 F.6.8 IM Flightcrew Flies IM Speeds … F-10 F.6.8.1 Compliance With IM Speeds … F-10 F.6.8.2 Mandatory Published Speeds … F-11 F.6.8.3 Compliance With Operational or Regulatory Speed Restrictions … F-11 F.6.9 IM Cancellation … F-11 F.7 Off-Nominal Situations … F-11 F.8 IM Flight Planning … F-12 F.8.1 IM Outside the U.S. NAS … F-12 F.8.2 FP Codes … F-12 F.9 Authorization to Conduct IM … F-12 F.9.1 Initial Request for Authorization … F-12 F.9.2 Documentation to Submit With Formal Request … F-12 F.9.2.1 Request Letter … F-12 F.9.2.2 Airplane Flight Manual (AFM) Compliance Documentation … F-13 F.9.2.3 Operation Manuals and Checklists … F-13 F.9.2.4 Maintenance Documentation … F-13 F.9.2.5 Revision of Minimum Equipment List (MEL) … F-13 F.9.2.6 Pilot Training … F-13 F.9.2.7 Dispatch/Flight Follower Training … F-14 ### Page 62 Appendix F F-3 F.1 Purpose. This appendix describes Interval Management (IM) and provides guidance to operators seeking FAA authorization to conduct IM operations. F.2 Background. The busiest airports operate most efficiently when air traffic control (ATC) delivers the arriving aircraft in a well-spaced sequence within an appropriate interval. The benefits of this spacing may include reduced fuel burn, reduced emissions, reduced noise, reduced ATC transmissions, and, as applied to the National Airspace System (NAS), greater throughput and reduced delays. IM is a set of procedures and capabilities designed to provide precise aircraft-to-aircraft spacing, and is suitable for use en route, on a terminal arrival, and final approach. It is an ADS-B In application that takes advantage of NAS-wide presence of ADS-B Out-equipped aircraft. F.3 IM Description. IM has a ground component and an airborne component. On the ground, ATC uses automation support tools to identify candidate pairs of IM aircraft and develop an IM clearance. The flight deck component, called Flight-deck Interval Management (FIM) avionics, consists of equipment that provides IM speeds to be flown by the flightcrew based on the information provided in the ATC clearance. The purpose of the IM clearance is to establish and maintain a precise spacing between a lead ADS-B Out aircraft and a trail IM aircraft. The IM speeds provided by the FIM avionics are expected to be flown as if each one was an individual ATC speed instruction for the duration of the IM procedure. The flightcrew complies with the ATC IM clearance by flying the IM speeds. ATC continues to retain responsibility for safe separation between the lead ADS-B Out aircraft and the trail IM aircraft, as well as all other aircraft. Note: Some may describe the IM aircraft as “following” a lead aircraft. The IM aircraft does not actually follow the lead aircraft but rather spaces from it in time or distance. At all times, each aircraft is navigating independently, as in non-IM operations. There are IM scenarios where the lead aircraft and IM aircraft are on different navigation routes and can be at different altitudes. F.3.1 IM Description—Ground Component. ATC initiates an IM operation when it is determined to be operationally beneficial. ATC, in conjunction with the IM automation support tool, identifies a candidate pair of aircraft consisting of a lead ADS-B Out aircraft and a FIM-equipped IM aircraft. The tool also calculates a desired spacing, called the assigned spacing goal (ASG). Based on when ATC needs the ASG, the controller can choose one of the IM clearance types (covered in paragraph F.5). F.3.2 IM Description—Airborne Component. IM is just one application that can be installed in approved ADS-B In avionics as described in Chapter 2, Overview and System Description, paragraph 2.4.1, and meets the performance requirements of Technical Standard Order (TSO)-C195c, Avionics Supporting Automatic Dependent Surveillance – Broadcast (ADS-B) Aircraft Surveillance Applications (ASA). As with other ADS-B In applications, FIM avionics consist of the Cockpit Display of Traffic Information (CDTI) and application-specific software. The CDTI consists of an input device for the IM clearance elements, a traffic display, and a means to display the IM speeds and provide FIM-specific indications and alerting. A speed algorithm calculates the IM speed: the indicated airspeed (IAS) or Mach number the flightcrew flies to ### Page 63 Appendix F F-4 achieve or maintain the ASG. Calculation of the IM speed is based on a number of variables, including the along-path distance between the two aircraft, their groundspeeds (GS), and the forecast winds and temperatures entered into the FIM avionics or other flight deck systems. The algorithm will limit calculated IM speeds to prevent overly large speed changes and exceeding certain aircraft, regulatory, or procedural limitations. Precise spacing requires that the algorithm use a defined horizontal and vertical path for both aircraft. Therefore, either both aircraft must be on the same horizontal, or near parallel route, or the lead aircraft’s navigation clearance1 must be provided to the FIM avionics. The FIM avionics monitor for horizontal path conformance of both the lead and IM aircraft and IM speed compliance. The avionics will provide appropriate indications to the flightcrew if any path conformance or speed compliance issues arise. 1 The lead aircraft’s navigation clearance may be provided as a named route or a sequence of waypoints. “Same route” may be used to indicate when the lead aircraft will be on the same route as the IM aircraft. F.3.3 Not ional Phraseology. IM has been developed through years of extensive study, simulation, and limited operational trials. However, at the time of this writing, the situations in which ATC may use IM, and the actual phraseology, are still evolving. Therefore, we use notional phraseology in this appendix to explain the IM procedure. We will add approved phraseology to subsequent revisions of this guidance. F.3.4 Early FIM Avionics. The early versions of FIM avionics may have only a subset of the full IM capabilities described in the avionics standards. We will identify any differences in this AC. As later versions of FIM avionics are produced that meet the full set of capabilities described in the avionics standards, we will revise this AC to reflect the added functionality. Additionally, equipment terminology may evolve as new FIM avionics designs are fielded. We will use terminology from the avionics standards in this AC. F.4 IM Terminology. We use the following terminology in this appendix. F.4.1 Assigned Spacing Goal (ASG). The time or distance interval between the IM aircraft and lead aircraft assigned by ATC in the IM clearance. The ASG includes both a value and unit of dimension as time or distance. F.4.2 Cross Point (CP). A point on the IM aircraft’s planned flightpath where the ASG is intended to be met. Also referred to as the “Achieve-by” point in industry standards. F.4.3 Designated Traffic. Traffic designated in the CDTI as the lead aircraft for a specific ADS-B In application. The FIM avionics will make designated traffic distinguishable from all other traffic on the traffic display. F.4.4 Flight-Deck Interval Management (FIM) Avionics. FIM avionics refer to the avionics that provide the IM capabilities defined in this AC. The FIM avionics act as the flightcrew interface and provide features like the IM clearance input interface and the display of IM speeds and any indications or alerts. ### Page 64 Appendix F F-5 F.4.5 Flight Identification (FLT ID). The flight identification, or FLT ID, can be the telephonic “call sign” (e.g., “Brickyard 3691”), the International Civil Aviation Organization (ICAO) three-letter designator (3LD) combined with a flight number (e.g., “RPA3691”), or the registration number of the aircraft (e.g., “N12345”). The FLT ID of the lead aircraft is given by ATC in the IM clearance. F.4.6 Interval Management (IM) Aircraft. An aircraft that is equipped with FIM avionics, flown by an IM-qualified flightcrew. F.4.7 Interval Management (IM) Clearance Type. The basic action that ATC instructs IM aircraft flightcrew to perform as part of the IM operations. The IM clearance types are Achieve-by Then Maintain, Maintain Current Spacing, Capture Then Maintain, Final Approach Spacing, and IM Turn. F.4.8 Interval Management (IM) Path Monitoring. An internal FIM avionics function that leads to the removal of IM information when either the IM aircraft or the lead aircraft vary from their expected route by a predetermined amount. F.4.9 Interval Management (IM) Speed. The speed in IAS or Mach calculated by the FIM avionics that the flightcrew flies to conform to the ATC IM clearance and to achieve or maintain the ASG. F.4.10 Interval Management (IM) Speed Compliance Monitoring. An internal FIM function designed to ensure precise flightcrew adherence to IM speed changes. The speed monitoring may include visual and aural alerting that notifies the flightcrew when the aircraft speed varies from the IM speed by a predetermined amount, or that the flightcrew has not responded to an IM speed change for a predetermined amount of time. F.4.11 Planned Cancellation Point (PCP). A point on the IM aircraft’s planned flightpath where the IM operations end normally. Also referred to as the “Planned Termination Point” in industry standards. F.4.12 Selected Traffic. Traffic uniquely chosen by the flightcrew via the CDTI to obtain additional information (e.g., FLT ID and GS). The FIM avionics will make selected traffic distinguishable from all other traffic on the traffic display. Selected traffic is not participating in an IM operation (but designated traffic is). F.5 IM Clearance Types Described. The FIM avionics standard contains five clearance types: Maintain Current Spacing, Capture Then Maintain, Achieve-by Then Maintain, Final Approach Spacing, and IM Turn. These clearance types describe the functions the FIM avionics perform; however, the terms used over the voice frequency and that are shown on the flightcrew interface may change to align with approved phraseology. ATC does not currently plan to implement the IM Turn clearance type in the NAS, so we do not address it here. We will add information related to IM Turn to a future revision of this appendix should that change. ### Page 65 Appendix F F-6 F.5.1 Clearance Type Format. Each clearance type has required clearance elements and optional clearance elements for ATC to provide. For all clearance types, ATC will provide the FLT ID of the lead aircraft along with the clearance type. For all clearance types, there is an ASG; ATC will state the ASG (in units of time or distance), or it will be implied (i.e., current spacing). ATC will provide the IM aircraft the planned route for the lead aircraft and the CP for the Achieve-by Then Maintain clearance type. The PCP is optional for all clearance types, but the FIM avionics will default the PCP in close proximity to the destination airport if a PCP is not entered. F.5.1.1 See Table F-1 for a summary of the acceptable clearance element formats. The ASG will be expressed in time (seconds) or distance. ATC will provide the CP and PCP as navigational fixes. The lead aircraft planned route will be given as a Standard Terminal Arrival Route (STAR), airway or approach procedure, or as a combination of those procedure types. Table F-1. Clearance Element Formats Clearance Element Format Examples Assigned spacing goal (ASG) Time or distance 90 seconds, 10 nautical miles (NM) Lead aircraft planned route Standard Terminal Arrival Route (STAR), airway, approach, waypoint, or sequence of waypoints EAGUL6, J186, ILS 36R Cross Point (CP) Navigation fix SLIDR, PINNG, 10 NM EAST OF SLIDR Planned Cancellation Point (PCP) Navigation fix EAGUL, DRRVR F.5.2 Maintain Current Spacing. ATC can issue a Maintain Current Spacing clearance expressed in either time or distance. For example, while an IM aircraft is transiting an en route sector, the controller seeing that the current spacing is suitable for delivery to the next sector gives the following: “TRAIL 456 Maintain current time behind LED123,” or “TRAIL 456 Maintain current distance behind LED123.” ### Page 66 Appendix F F-7 Figure F-1. Maintain Current Spacing F.5.3 Capture Then Maintain. ATC can issue a Capture Then Maintain clearance when the IM aircraft and the lead aircraft are on similar routes. The FIM avionics will provide IM speeds to move the IM aircraft to the ASG. A sample IM clearance could be: “TRAIL 456 Capture then maintain 10NM behind LED123.” Figure F-2. Capture Then Maintain F.5.4 Achieve-by Then Maintain (“Cross”). When ATC needs the ASG achieved by the time the IM aircraft reaches a particular fix, the controller may issue an Achieve-by Then Maintain clearance. The lead aircraft and IM aircraft may be on different paths at the time of the clearance, but will cross a common fix. The clearance will contain the lead aircraft’s planned route and the identification of the fix to cross, and optionally the PCP. The ASG can be expressed in time or distance. An example could be: “TRAIL 456 Cross HONEE 90 seconds behind LED123 on the BRAVO Transition. Cancel at LASFX.” The IM flightcrew will fly the IM speeds to achieve the ASG by the time they cross the CP. They will maintain the ASG until the PCP, or until the controller cancels the IM operation. ### Page 67 Appendix F F-8 Figure F-3. Achieve-by Then Maintain (Cross) F.5.5 Fi nal Approach Spacing. ATC may issue a Final Approach Spacing clearance when one or both of the lead aircraft and the IM aircraft will be on the same final approach course. One aircraft can be on an intercept to final if the other aircraft is already established on the final approach course. The controller will include the lead Aircraft Identification (ACID) and the ASG. Figure F-4. Final Approach Spacing F.5.6 IM Suspend. ATC may have a need to interrupt an active IM operation, such as to resolve a developing traffic conflict. IM Suspend is not strictly a clearance type. It is functionality in the FIM avionics that temporarily removes IM speeds, indications, and alerts, but retains the basic IM clearance information. F.5.7 SafeRoute+ Differences. SafeRoute+ is the Aviation Communication & Surveillance Systems’ (ACSS) commercial name for the only FIM avionics in production at the time of this writing (2025). It contains a subset of the standard IM functions and has some functionality that differs from the industry standard. The SafeRoute+ avionics only accommodate two of the clearance types (i.e., Capture Then Maintain and Achieve-by Then Maintain), and they differ slightly from the standards invoked in TSO-C195c. F.5.7.1 Maintain Current Spacing and Capture Then Maintain. In the absence of an ASG entry by the flightcrew, the SafeRoute+ FIM avionics calculate IM speeds to maintain the current spacing. A time or distance input must still be made by the flightcrew. ### Page 68 Appendix F F-9 F.5.7.2 Achieve-by Then Maintain. A SafeRoute+ Achieve-by Then Maintain clearance differs from the standards in two ways. It does not accept the lead aircraft’s planned route; therefore, the lead aircraft and IM aircraft must be flying direct to a common merge point. F.5.7.3 No IM Suspend. SafeRoute+ does not include a “suspend” function. Instead, the pilot uses the “terminate” (also known as “cancel”) function. Table F-2. Interval Management Clearance Types Summarized Clearance Type Maintain Capture Then Maintain Cross Final Approach Spacing Notional Phraseology “TRAIL 456 Maintain distance behind LED123” “TRAIL 456 Maintain 90 seconds behind LED123” (or “Maintain 10 miles”) “TRAIL 456 Cross HONEE 90 seconds behind LED123 on the BRAVO transition. Cancel at LASFX.” “TRAIL 456 Cross GOSER 90 seconds behind LED123” Clearance Elements Lead A/C FLT ID Lead A/C FLT ID Lead A/C FLT ID Lead A/C FLT ID ASG (implied) ASG ASG ASG CP Lead aircraft planned route if different than the IM aircraft planned route Lead aircraft planned route if different than the IM aircraft planned route PCP (optional) PCP (optional) PCP PCP defaulted Notes Underline indicates clearance type cue. Not in SafeRoute+. Underline indicates clearance type cue. Lead aircraft is on different route— “BRAVO” transition. Not in SafeRoute+. F.6 IM Procedure. ATC may initiate an IM operation when operationally beneficial. The IM operations will proceed as follows: F.6.1 ATC Identifies IM Pair. Using automation support tools, ATC identifies the potential IM lead aircraft and IM aircraft, ASG, CP (when applicable), and PCP. F.6.2 ATC Checks Feasibility. ATC, supported by automation, determines the feasibility of the IM operation. Some of the factors used in this determination are current spacing, remaining distance, conflicting traffic, and weather. F.6.3 ATC Issues IM Clearance. ATC issues the IM clearance to the IM aircraft flightcrew using one of the four clearance types. ### Page 69 Appendix F F-10 F.6.4 IM Flightcrew Reads Back Clearance. The IM aircraft flightcrew reads back the IM clearance and enters the IM clearance information into the FIM avionics. F.6.5 IM Flightcrew Verifies Lead Aircraft. The flightcrew verifies that they have selected the correct lead aircraft and that they have entered the IM clearance elements correctly. F.6.5.1 FLT ID Verification. Verifying the correct lead aircraft is an essential step. It can be complicated by two factors. The first factor is that the telephonic or spoken call sign of the lead aircraft might not easily translate into the FLT ID displayed by the FIM avionics. For example, “Brickyard” does not readily translate to “RPA.” The second factor is that the lead aircraft or nearby nonparticipating aircraft might have erroneously programmed their FLT ID in their ADS-B Out system. The flightcrew should not accept the IM clearance if there is any doubt that they have correctly identified the lead aircraft as that given in the IM clearance. F.6.6 FIM Avionics Internal Check. The FIM avionics perform an internal check to ensure all performance criteria are met. If the performance criteria are met, the FIM avionics display the first IM speed. F.6.7 IM Flightcrew Evaluates IM Speed. The flightcrew evaluates the IM speed to determine whether it is acceptable given operational considerations, such as ride conditions and own aircraft limitations. F.6.7.1 Rejected Clearance. If the flightcrew determines that the IM speed is unacceptable, they will immediately notify ATC that they are unable to accept the IM clearance. F.6.7.2 Accepted Clearance. If the flightcrew determines that the IM speed is acceptable, they begin complying with the IM speeds with no further instruction by ATC (i.e., further read-back or reporting the implementation of each IM speed). ATC does not require any further acknowledgment by the flightcrew that they have accepted the IM clearance. This is similar to acknowledging a clearance to descend or climb; ATC expects the flightcrew to promptly comply or notify ATC that they are unable to comply. F.6.8 IM Flightcrew Flies IM Speeds. The FIM avionics calculate IM speeds to maintain or achieve the ASG. In the case of an Achieve-by Then Maintain (also known as “Cross”) clearance, the IM speeds are flown to achieve the ASG by the time the IM aircraft reaches the CP. In the case of a Capture Then Maintain clearance, the IM speeds are flown to achieve the ASG quickly and then maintain that ASG until reaching the PCP. F.6.8.1 Compliance With IM Speeds. It is important to emphasize that flightcrews should resist the temptation to “out-guess” the FIM algorithm by flying speeds other than the IM speed. Flying the IM speeds is how the flightcrew complies with the ATC-issued IM clearance. The FIM algorithm is designed to account for speed changes that result from the lead aircraft trajectory as well as actual winds encountered along the IM aircraft’s route, which inevitably will differ ### Page 70 Appendix F F-11 from the forecast winds entered in the FIM avionics. Not complying with the IM speed will make precise IM spacing more difficult and could lead to the need to fly more IM speeds than necessary. F.6.8.2 Mandatory Published Speeds. The mandatory speeds published on STAR procedure charts are designed to condition the flow of traffic into the terminal arrival area. They are the basis for the speed profile used by the FIM avionics to calculate estimated times of arrival (ETA) at CP when using an Achieve-by Then Maintain clearance type and to calculate speed limits on the IM speed. The IM speeds supersede the published speeds when operating on an IM clearance. Published speeds are used by the FIM avionics in the calculation of the trajectory of the lead aircraft and, hence, the IM speeds. Flightcrews need to continue to comply with the IM speed unless directed by ATC. F.6.8.3 Compliance With Operational or Regulatory Speed Restrictions. It is the flightcrew’s responsibility to ensure that each IM speed does not conflict with any operational or regulatory speed restrictions. IM speeds do not supersede regulatory speed restrictions, such as 250 knots indicated airspeed (KIAS) below 10,000 feet mean sea level (MSL) in the United States. They also do not supersede the aircraft’s various operational speed restrictions. FIM avionics will limit IM speeds to within the operational limits of the aircraft, and not conflict with regulatory speed limits described here. F.6.9 IM Cancellation. The IM aircraft flightcrew complies with the IM speeds until the procedure is canceled. When the IM operation is canceled, the FIM avionics no longer provide IM speeds or alerts. Upon IM cancellation, the flightcrew complies with speeds as instructed by ATC, as published, or as the last IM speed displayed. The IM operation will be canceled in one of the following ways: • Automatically by the FIM avionics upon reaching the PCP; • Manually by the flightcrew upon ATC instruction; • Manually by the flightcrew for other operational reasons (which must be followed with a report to ATC); or • Automatically due to certain off-nominal situations (which must be followed with a report to ATC if the flightcrew determined the operation needed to end). F.7 Off-Nominal Situations. The IM procedure depends upon multiple factors: accurate wind and temperature profiles, close adherence to IM speed, and both aircraft adhering to their planned flight profiles. FIM avionics incorporate internal checks that verify that the horizontal navigation path of the IM aircraft and the lead aircraft are in acceptable limits for the IM procedure. Speed compliance monitoring by the FIM avionics assists the IM aircraft flightcrew with implementing the displayed IM speed. In the event the flightcrew is unable to continue conforming to the IM clearance by flying the IM speeds, they must notify ATC. ### Page 71 Appendix F F-12 F.8 IM Flight Planning. IM flight planning should take into consideration the capabilities of the aircraft, flightcrew, and air navigation service providers (ANSP) where IM is conducted. ATC will need to know in advance which aircraft are FIM-equipped and that the flightcrew is approved to conduct IM. To facilitate this, correct aircraft equipment codes will need to be entered on the flight plan (FP). F.8.1 IM Outside the U.S. NAS. In the future, ANSPs outside the United States may conduct IM. Before conducting IM operations outside the U.S. NAS, determine whether the destination ANSP provides IM services that are compliant with existing ICAO guidance. F.8.2 FP Codes. The FAA is adopting ADS-B In FP capability indicators for ADS-B In operations that require specific equipment, training, and authorization. The capability indicators tell ATC that the necessary equipment is on board the aircraft and operable, and that the flightcrew is qualified and authorized to conduct the indicated ADS-B In operations. When authorized and equipped to conduct IM using ACSS SafeRoute+, enter “SUR/I0” in FP Item 18 and ensure that the ADS-B capability code entered in FP Item 10 reflects ADS-B In capability. Refer to the Aeronautical Information Manual (AIM), Chapter 5, Air Traffic Procedures, for complete instructions on filing ADS-B equipment codes. F.9 Authorization to Conduct IM. FAA authorization is required for all U.S. aircraft operators to conduct IM operations using ADS-B In (14 CFR § 119.49(a)(5)). For FAA authorization, refer to FAA Order 8900.1, Volume 3, Chapter 18, Section 3, Operations Specification (OpSpec)/Management Specification (MSpec)/Letter of Authorization (LOA) A355, Automatic Dependent Surveillance-Broadcast (ADS-B) In Operations. F.9.1 Initial Request for Authorization. U.S. aircraft operators seeking to conduct IM should first contact their assigned FAA office to indicate their intent. At the time of the operator’s initial request, the FAA will provide the operator with an IM Application Checklist, which should be completed with attached supporting documents. F.9.2 Documentation to Submit With Formal Request. This paragraph describes the documentation to be submitted with a formal IM proposal. F.9.2.1 Request Letter. The operator’s assigned principal inspector (PI) may ask for additional information based on any unique aspects of their specific operation. The operator should submit a letter of request for issuance of authorization to the assigned PI. The letter may be in a form acceptable to the Administrator (e.g., as an electronic document entered into the Operations Approval Portal System (OAPS)). The letter of request should include the following information: • Type of aircraft (make, model, and series (M/M/S)). • List of aircraft registration numbers (N-number) associated with the request for authorization. ### Page 72 Appendix F F-13 • ADS-B equipment complies with TSO-C195c or later revision, or as approved for IM by the Administrator. • Installation was completed following guidance contained in AC 20-165, Airworthiness Approval of Automatic Dependent Surveillance - Broadcast OUT Systems, and AC 20-172, Airworthiness Approval for ADS-B In Systems and Applications, or other acceptable means. • Name of the ADS-B In (IM) software manufacturer and applicable software version(s). • Intended areas of IM operations, listed by ANSP. F.9.2.2 Airplane Flight Manual (AFM) Compliance Documentation. Operators will submit documentation that demonstrates applicable aircraft have an ADS-B In system that meets the performance standards of TSO-C195c or later revision, or as otherwise approved by the Administrator, for IM operations. F.9.2.3 Operation Manuals and Checklists. The certificate holder (CH)/operator/program manager (as applicable) should submit information (e.g., Airplane Operations Manual (AOM) bulletin or equivalent) to the flightcrews describing ADS-B, to include: • IM system description; • Normal procedures; and • Non-normal or contingency procedures. F.9.2.4 Maintenance Documentation. See Appendix C, ADS-B In Operations— Aircraft Qualification and Maintenance, for applicable maintenance guidance. F.9.2.5 Revision of Minimum Equipment List (MEL). See Appendix C for guidance on the necessary MEL documents to be submitted for authorization of IM. F.9.2.6 Pilot Training. Submit applicable portions of proposed IM-specific pilot training material and include a description of the methods used to conduct, evaluate, and manage the training. The IM pilot training should include: 1. ADS-B Out/In system overview (if not previously addressed with another ADS-B application). 2. ADS-B IM system operations. 3. IM normal procedures: • Understanding IM clearance types and clearance elements. • Compliance with IM speed. ### Page 73 Appendix F F-14 • Response to IM alerts. • Lead aircraft FLT ID verification. • Crew coordination during IM. 4. IM MEL procedures (as applicable). 5. IM equipment limitations. 6. CDTI interface. 7. Contingency procedures. F.9.2.7 Dispatch/Flight Follower Training. Submit applicable portions of proposed IM-specific dispatch/flight planning training material, to include any appropriate updates to the dispatch operations manual, or equivalent, as well as a description of the methods used to conduct, evaluate, and manage training. The training material should include: 1. General understanding of ADS-B In operations. 2. Correct flight planning codes for IM operations, including the ACID. A correct ACID in the FP is essential to the IM operation. Before ATC can commence an IM operation, the transmitted FLT ID from the lead aircraft must exactly match that from the FP. While filing ACID refers directly to the ADS-B Out aircraft, it can adversely impact an IM operation. 3. Dispatch of aircraft with the FIM system unserviceable. 4. How flight planning codes are affected with ADS-B or FIM avionics unserviceable. 5. Equipment needed to conduct IM. 6. ANSPs and airspace where IM operations are approved. ### Page 74 Appendix G G-1 APPENDIX G. CDTI ASSISTED SEPARATION ON APPROACH CONTENTS Paragraph Page G.1 Purpose … G-3 G.2 Background … G-3 G.3 CAS-A Concept … G-3 G.3.1 CAS-A Concept—Ground Component … G-3 G.3.2 CAS-A Concept—Airborne Component … G-3 G.3.3 Notional Phraseology … G-4 G.4 CAS-A Terminology … G-4 G.4.1 Cockpit Display of Traffic Information (CDTI) Assisted Separation on Approach (CAS-A) Aircraft … G-4 G.4.2 Cockpit Display of Traffic Information (CDTI) Assisted Separation on Approach (CAS-A) Avionics … G-4 G.4.3 Designated Traffic … G-4 G.4.4 Flight Identification (FLT ID) … G-4 G.4.5 Selected Traffic … G-4 G.5 CAS-A Communications Described … G-4 G.6 CAS-A Procedure … G-4 G.6.1 Controller Identifies CAS-A TTF Aircraft … G-5 G.6.2 Flightcrew Reads Back the Designation Instruction … G-5 G.6.3 Flightcrew Verifies TTF Aircraft … G-5 G.6.3.1 FLT ID Verification … G-5 G.6.3.2 CAS-A Avionics Performs Internal Checks … G-5 G.6.3.3 Flightcrew Confirms TTF Designation With the Controller … G-5 G.6.4 Controller Issues Instruction to Follow the Designated Traffic Along With Approach Clearance … G-6 G.6.4.1 Accepted CAS-A Instruction to Follow the Designated TTF … G-7 G.6.4.2 Rejected Clearance … G-7 G.6.5 Flightcrew Flies Normal Approach Procedure … G-7 G.6.6 CAS-A Cancellation … G-7 G.7 CAS-A Alerting … G-7 G.7.1 Selectable Range Indication … G-7 ### Page 75 Appendix G G-2 G.7.2 Minimum Range Alert … G-7 G.8 Off-Nominal Situations … G-8 G.9 CAS-A FP Codes … G-8 G.10 Authorization to Conduct CAS-A … G-8 G.10.1 Initial Request for Authorization … G-8 G.10.2 Documentation to Submit With Formal Request … G-8 G.10.2.1 Request Letter … G-8 G.10.2.2 Airplane Flight Manual (AFM) Compliance Documentation … G-9 G.10.2.3 Operation Manuals and Checklists … G-9 G.10.2.4 Maintenance Documentation … G-9 G.10.2.5 Revision of Minimum Equipment List (MEL) … G-9 G.10.2.6 Pilot Training … G-9 G.10.2.7 Dispatch/Flight Follower Training … G-10 ### Page 76 Appendix G G-3 G.1 Purpose. This appendix describes Cockpit Display of Traffic Information (CDTI) Assisted Separation on Approach (CAS-A) and provides guidance to operators seeking FAA authorization to conduct CAS-A operations. G.2 Background. To realize maximum runway capacity, operations at some airports are based on a flightcrew maintaining visual separation from traffic-to-follow (TTF). The objective of CAS-A is to maintain visual-like separation safely and more efficiently from TTF than visual separation alone, using the information on the CDTI during approach procedures. It is expected to recapture some of the runway capacity benefits of visual separation operations during weather conditions that do not support visual approaches with pilot-applied visual separation, and during visual approach conditions when pilot identification of the TTF or the airport out the window (OTW) may be delayed due to restrictions to visibility, such as haze or intervening clouds. An early operational trial of CAS-A has shown that airport capacity improves because the CAS-A aircraft and nearby subsequent aircraft fly fewer miles to the runway in terminal airspace. CAS-A is an operation that builds on the existing CDTI Assisted Visual Separation (CAVS) operation, as described in Appendix B, CAVS Using ADS-B In, and uses the same flight deck avionics as required for CAVS. G.3 CAS-A Concept. Unlike CAVS, the CAS-A operation is initiated by the controller, who provides a CAS-A designation instruction that includes the flight identification (FLT ID) for the TTF. The flightcrew identifies the TTF on the CDTI using the FLT ID provided by the controller (visual acquisition is not required). After the flightcrew has reported the TTF designated, the controller can give the CAS-A instruction to follow the TTF and an approach clearance. Once the flightcrew accepts the CAS-A instruction to follow the TTF, the controller is no longer required to apply radar separation, and the flightcrew uses the TTF information available on the CDTI to manage their distance and closure. CAS-A can only be used when both aircraft are on approach to the same runway and the airport of intended landing has a reported ceiling of 1,000 feet or greater and visibility of 3 statute miles (sm) or greater. The aircraft conducting a CAS-A operation may enter instrument meteorological conditions (IMC) during flight, unless on a visual approach, where the aircraft must remain clear of clouds. CAS-A does not change any requirements for instrument or visual approach procedures. It allows the flightcrew to use the CDTI alone to maintain separation from the TTF when OTW visual contact is not possible or is lost. Acquisition of the TTF OTW is not required for CAS-A but may occur if conditions allow for it. G.3.1 CAS-A Concept—Ground Component. To give a CAS-A instruction, the controller will have a means to identify candidate CAS-A aircraft. The controller is also expected to use current automation features to indicate when a TTF aircraft is designated and/or when a CAS-A aircraft is conducting CAS-A. No additional ground automation is required. G.3.2 CAS-A Concept—Airborne Component. The CAS-A aircraft must have CAVS application software and equipment that is compliant with Technical Standard Order (TSO)-C195b, Avionics Supporting Automatic Dependent Surveillance – Broadcast (ADS-B) Aircraft Surveillance Applications (ASA), or later revision. ### Page 77 Appendix G G-4 G.3.3 Notional Phraseology. At the time of this writing, the actual phraseology is still evolving. Therefore, we use notional phraseology in this appendix to explain the procedure. We will add approved phraseology to subsequent revisions of this guidance. G.4 CAS-A Terminology. We use the following terminology in this appendix. G.4.1 Cockpit Display of Traffic Information (CDTI) Assisted Separation on Approach (CAS-A) Aircraft. An aircraft that is equipped with CAS-A avionics, flown by a CAS-A-qualified flightcrew. G.4.2 Cockpit Display of Traffic Information (CDTI) Assisted Separation on Approach (CAS-A) Avionics. CAS-A avionics refer to the avionics that provide the CAS-A capabilities defined in this appendix. The CAS-A avionics provide a means to designate the TTF using the FLT ID. It displays range and differential groundspeed (GS) to designated TTF. It also displays CAS-A-related indications and alerts. In this appendix, we will refer to CAS-A avionics recognizing that CAS-A and CAVS avionics are one and the same. The CAS-A avionics also include an ability to “select” traffic (see below), but designation is required to conduct CAS-A. G.4.3 Designated Traffic. Traffic designated in the CDTI as the TTF for a specific ADS-B In application, in this case CAS-A. The CAS-A avionics will make designated traffic distinguishable from all other traffic on the traffic display and will provide range and differential GS to designated traffic, as well as internal checking and alerting. G.4.4 Flight Identification (FLT ID). The flight identification, or FLT ID, can be the International Civil Aviation Organization (ICAO) three-letter designator (3LD) combined with a flight number (e.g., “RPA3691”), or other Aircraft Identification (ACID) as entered on the flight plan (FP) (e.g., N12345). The controller will include the FLT ID of the TTF as part of the CAS-A designation instruction. The CAS-A crew will designate the TTF using the FLT ID in the CAS-A avionics. G.4.5 Selected Traffic. A selection feature is available in the CAS-A avionics but is not required nor sufficient to conduct CAS-A. Selection does not provide the necessary information, internal checking, or alerting. Selected traffic is not participating in a CAS-A operation (only designated traffic can be). Selection of traffic can be used to gain additional information on traffic before designation or to gain additional information on other non-CAS-A traffic. G.5 CAS-A Communications Described. The CAS-A communications consist of two parts: the designate instruction and the instruction to follow the designated TTF. Along with the CAS-A communications, the controller will also issue a visual or an instrument approach clearance. The controller indicates the intention to issue a CAS-A clearance by instructing the CAS-A flightcrew to designate a specific aircraft as the TTF. Once the flightcrew has designated the TTF, the controller can issue an approach clearance, visual or instrument. G.6 CAS-A Procedure. The controller initiates a CAS-A operation when it is operationally beneficial. The CAS-A operation proceeds as follows: ### Page 78 Appendix G G-5 G.6.1 Controller Identifies CAS-A TTF Aircraft. The controller issues the following instruction to the CAS-A aircraft: “[CAS-A aircraft FLT ID] DESIGNATE [TTF FLT ID] AND REPORT.” An example of this instruction could be: “Trail 456 designate Lead 123 and report.” Figure G-1. Controller Identifies CAS-A TTF Aircraft G.6.2 F lightcrew Reads Back the Designation Instruction. The CAS-A aircraft flightcrew reads back the designate instruction and enters the TTF FLT ID into the CAS-A avionics. G.6.3 Flightcrew Verifies TTF Aircraft. The flightcrew first verifies amongst themselves that they have designated the correct TTF aircraft. G.6.3.1 FLT ID Verification. Verifying the correct TTF FLT ID aircraft is an essential step. It can be complicated by two factors. The first factor is that the controller may use the telephonic call sign of the TTF, which might not easily translate into the FLT ID displayed by the CAS-A avionics. For example, “Brickyard” does not readily translate to “RPA.” In these cases, the controller can choose to identify the TTF company as “Romeo Papa Alpha” or “R-P-A,” followed by the number. Additionally, the flightcrew can read back the TTF company with either of those options. The second factor is that the TTF or nearby nonparticipating aircraft might have erroneously programmed their FLT ID in their ADS-B Out system. The flightcrew should not accept the CAS-A clearance if there is any doubt that they have correctly identified the TTF as that given in the designate instruction. G.6.3.2 CAS-A Avionics Performs Internal Checks. Once the TTF is designated, the CAS-A avionics perform internal checks to ensure that the ADS-B Out signal from the TTF and the ADS-B In equipment on the CAS-A aircraft meet the minimum requirements to support the CAS-A operation. The avionics will issue appropriate alerts if the requirements are not met. G.6.3.3 Flightcrew Confirms TTF Designation With the Controller. When the flightcrew confirms the appropriate TTF has been designated, they report the designation, with the TTF FLT ID, to the controller as follows: “[CAS-A aircraft FLT ID] HAS DESIGNATED [TTF FLT ID]. An example of this could be: “Trail 456 has designated Lead 123.” The controller must receive ### Page 79 Appendix G G-6 confirmation of the TTF FLT ID prior to issuing the instruction to follow the designated TTF. Reporting designation with the correct FLT ID lets the controller know that the correct aircraft is identified. After this, the flightcrew can expect an instruction from the controller to follow the TTF, along with, or after, an approach clearance. Note: Selecting the TTF is not sufficient for conducting CAS-A because the avionics do not provide the necessary information, internal checking, or alerting. The TTF must be designated. Important: To avoid extra communications, the CAS-A flightcrew is expected to report that they have designated the TTF, even if the controller does not request a report. If the controller does not receive confirmation of the TTF FLT ID from the flightcrew prior to issuing the CAS-A clearance, the controller must ensure with the flightcrew that the correct traffic is designated with additional communication: • Controller Message: “[CAS-A aircraft FLT ID] VERIFY TRAFFIC IS DESIGNATED” (e.g., “Trail 456 verify traffic is designated”). • Flightcrew Message: “[CAS-A aircraft FLT ID] HAS DESIGNATED [TTF FLT ID]” (e.g., “Trail 456 has designated Lead 123”). G.6.4 Controller Issues Instruction to Follow the Designated Traffic Along With Approach Clearance. After the TTF designation has been reported by the flightcrew and confirmed by the controller, the controller can issue an instruction to follow the TTF and an approach clearance, at the appropriate time. • Controller Message: “[CAS-A aircraft FLT ID], FOLLOW DESIGNATED TRAFFIC, [approach clearance]” (e.g., “Trail 456, follow designated traffic, cleared visual approach Runway two-seven left”). • Flightcrew Message: “[CAS-A aircraft FLT ID], FOLLOW DESIGNATED TRAFFIC, [approach clearance]” (e.g., “Trail 456, follow designated traffic, cleared visual approach Runway two-seven left”). Figure G-2. Controller Issues Instruction to Follow the Designated Traffic Along With Approach Clearance ### Page 80 Appendix G G-7 G.6.4.1 Accepted CAS-A Instruction to Follow the Designated TTF. Once the flightcrew accepts the instruction to follow the designated traffic, the controller is relieved of the requirement to apply radar separation between the CAS-A aircraft and TTF. G.6.4.2 Rejected Clearance. If the flightcrew determines that the CAS-A instruction/operation is unacceptable, they will immediately notify the controller that they are unable to accept or continue the CAS-A operation. At this point, the controller will cancel CAS-A and provide alternative instructions. G.6.5 Flightcrew Flies Normal Approach Procedure. The CAS-A avionics calculate the range and differential GS between the designated aircraft (i.e., TTF) and the CAS-A aircraft. The flightcrew uses this information to monitor their distance and closure from the TTF as they fly their normal approach profile. CAS-A is not intended to manage a specific, precise spacing from the TTF. Rather, it is an aid to manage distance and closure from the TTF while flying the normal approach procedure. G.6.6 CAS-A Cancellation. The CAS-A operation is canceled in one of the following ways: • The TTF lands, • The Traffic Lost Advisory Alert is triggered, or • The controller cancels for operational reasons or upon flightcrew request. G.6.6.1 When the TTF lands, or if the Traffic Lost Advisory Alert is triggered, the CAS-A avionics will automatically terminate CAS-A in the CAS-A avionics and no longer provide distance information, differential GS, or alerts. G.6.6.2 If the controller cancels the CAS-A operation, the flightcrew should terminate CAS-A in the avionics, so the avionics no longer display distance information, differential GS, or alerts. G.7 CAS-A Alerting. CAS-A installations compliant with TSO-C195b or later revision, incorporate two unique alerting features: a caution level minimum range alert and an advisory level selectable range indication. G.7.1 Selectable Range Indication. The flightcrew-selectable range indication alert is used to advise the flightcrew that the CAS-A aircraft is at the selected range from the TTF. The range indication is set in accordance with individual established company procedures and is intended to assist the flightcrew in maintaining a safe distance from the TTF. G.7.2 Minimum Range Alert. The caution level minimum range alert is activated when the range to the TTF is less than 0.42 nautical miles (NM), and can be issued on traffic that is within 1.4 NM under certain conditions. This alert cannot be modified by the flightcrew and indicates that, due to uncertainty in the ADS-B positions at such close ranges, the CDTI cannot safely be used to determine the position of the TTF. ### Page 81 Appendix G G-8 G.8 Off-Nominal Situations. In the event the flightcrew is unable to continue conforming to the CAS-A clearance, they must notify the controller. Such instances include: • A sustained loss of ADS-B data quality and/or integrity, as indicated to the flightcrew via the CDTI. • When the caution level minimum range alert is activated. • If the flightcrew is unable to maintain a safe distance for any reason, in which case they must immediately advise the controller and request further instructions. G.9 CAS-A FP Codes. The controller will need to know in advance which aircraft are CAS-A-equipped and that the flightcrew is approved to conduct CAS-A. To facilitate this, correct aircraft equipment codes will need to be entered on the FP. The ADS-B capability code entered in FP Item 10 should reflect ADS-B In capability, as described in paragraph 4.4.2. When authorized and equipped to conduct CAS-A, “SUR/C2” should be added to FP Item 18 for the controller to recognize that capability. G.10 Authorization to Conduct CAS-A. FAA authorization is required for all U.S. aircraft operators to conduct CAS-A operations using ADS-B In (14 CFR § 119.49(a)(5)). For FAA authorization, refer to FAA Order 8900.1, Volume 3, Chapter 18, Section 3, Operations Specification (OpSpec)/Management Specification (MSpec)/Letter of Authorization (LOA) A355, Automatic Dependent Surveillance-Broadcast (ADS-B) In Operations. G.10.1 Initial Request for Authorization. U.S. aircraft operators seeking to conduct CAS-A should first contact their assigned FAA office to indicate their intent. At the time of the operator’s initial request, the FAA will direct the operator to the appropriate guidance describing the documents required for submission. G.10.2 Documentation to Submit With Formal Request. The documentation to be submitted with a formal CAS-A proposal is as follows. G.10.2.1 Request Letter. The operator’s assigned principal inspector (PI) may ask for additional information based on any unique aspects of their specific operation. The operator should submit a letter of request for issuance of authorization to the assigned PI. The letter may be in a form acceptable to the Administrator (e.g., as an electronic document entered into the Operations Approval Portal System (OAPS)). The letter of request should include the following information: • Type of aircraft (make, model, and series (M/M/S)). • List of aircraft registration numbers (N-number) associated with the request for authorization. • ADS-B equipment complies with TSO-C195b or later revision, or as approved for CAS-A by the Administrator. ### Page 82 Appendix G G-9 • Statement or documentation that the installation complies with guidance contained in AC 20-165, Airworthiness Approval of Automatic Dependent Surveillance - Broadcast OUT Systems, and AC 20-172, Airworthiness Approval for ADS-B In Systems and Applications. • Name of the ADS-B In (CAS-A) software manufacturer and applicable software version(s). • Intended airports of CAS-A operations. G.10.2.2 Airplane Flight Manual (AFM) Compliance Documentation. Operators will submit documentation that demonstrates applicable aircraft have an ADS-B In system that meets the performance standards of TSO-C195b or later revision, or as otherwise approved by the Administrator, for CAS-A operations. This documentation may be omitted for aircraft already approved for CAVS. G.10.2.3 Operation Manuals and Checklists. The certificate holder (CH)/operator/program manager (as applicable) should submit information (e.g., Airplane Operations Manual (AOM) bulletin or equivalent) to the flightcrews describing ADS-B, to include: • CAS-A system description; • Normal procedures; and • Non-normal or contingency procedures. G.10.2.4 Maintenance Documentation. See Appendix C, ADS-B In Operations— Aircraft Qualification and Maintenance, for applicable maintenance guidance. G.10.2.5 Revision of Minimum Equipment List (MEL). See Appendix C for guidance on the necessary MEL documents to be submitted for authorization of CAS-A. G.10.2.6 Pilot Training. Submit applicable portions of proposed CAS-A-specific pilot training material and include a description of the methods used to conduct, evaluate, and manage the training. The CAS-A pilot training should include: 1. ADS-B Out/In system overview (if not previously addressed with another ADS-B application). 2. ADS-B CAS-A system operations. 3. CAS-A normal procedures: • Understanding CAS-A communications and the associated phraseology. • Response to CAS-A indications and alerts. ### Page 83 Appendix G G-10 • TTF aircraft FLT ID verification. • Crew coordination during CAS-A. 4. CAS-A MEL procedures (as applicable). 5. CAS-A equipment limitations. 6. CDTI interface. 7. Contingency procedures. G.10.2.7 Dispatch/Flight Follower Training. Submit applicable portions of proposed CAS-A-specific dispatch/flight planning training material, to include any appropriate updates to the dispatch operations manual, or equivalent, as well as a description of the methods used to conduct, evaluate, and manage training. The training material should include: 1. General understanding of ADS-B In operations. 2. Correct flight planning codes for CAS-A operations, including the ACID. 3. Dispatch of aircraft with the CAS-A system inoperative. 4. How flight planning codes are affected with ADS-B or CAS-A avionics inoperative. 5. Equipment needed to conduct CAS-A. ### Page 84 Advisory Circular Feedback Form If you find an error in this AC, have recommendations for improving it, or have suggestions for new items/subjects to be added, you may let us know by contacting the Flight Technologies and Procedures Division at 9-AWA-AFS400-Coord@faa.gov or the Flight Standards Directives Management Officer at 9-AWA-AFB-120-Directives@faa.gov. Subject: AC 90-114C, Automatic Dependent Surveillance-Broadcast Operations Date: _____________________ Please check all appropriate line items: An e rror ( proc edural or typographical) has been noted in paragraph ____________ on page _______. Recommend paragraph _____________ on page __________ be changed as follows: ______________________________________________________________________ ______________________________________________________________________ In a future change to this AC, please cover the following subject: (Briefly describe what you want added.) ______________________________________________________________________ ______________________________________________________________________ Other comments: ______________________________________________________________________ ______________________________________________________________________ I would like to discuss the above. Please contact me. 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