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
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CONTENTS Paragraph Page
Chapter 1. Automatic Dependent Surveillance-Broadcast Operations1-1
1.1 Purpose of This Advisory Circular (AC)1-1
1.2 Audience1-1
1.3 Where You Can Find This AC1-1
1.4 What This AC Cancels1-1
1.5 Scope1-1
1.6 AC Feedback Form1-2
Chapter 2. Overview and S ystem Description2-1
2.1 Overview2-1
2.2 ADS-B System Description2-1
2.3 ADS-B Broadcast Services2-2
2.4 Use of ADS-B In Information for Traffic Situational Awareness2-2
Chapter 3. Operational Considerations3-1
3.1 U.S. ADS-B Airspace and Equipment Performance Requirements3-1
3.2 Exceptions to Airspace Requirements3-3
3.3 Traffic Awareness Beacon System (TABS)3-3
Chapter 4. Operating Procedures4-1
4.1 General Operating Procedures4-1
4.2 Operator Familiarity of the Installed ADS-B System4-1
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 Data4-15
Appendix A. ADS-B In-T rail ProcedureA-1
Appendix B. CAVS Us ing ADS-B InB-1
Appendix C. ADS-B I n Operations—Aircraft Qualification and MaintenanceC-1
Appendix D. De finitionsD-1
Appendix E. Rel ated Regulations and Reading MaterialE-1
Appendix F. In terval ManagementF-1
Appendix G. CDTI Assisted Separation On ApproachG-1
iii List of Figures Figure 3-1. Automatic Dependent Surveillance-Broadcast Airspace Rule
(14 CFR § 91.225) Diagram3-2
Figure A-1. R eduction of Aircraft Separation Minima With In-Trail ProcedureA-1
Figure A-2. In-T rail Procedure Distances IllustratedA-3
Figure A-3. S imilar TrackA-4
Figure A-4. In-T rail Procedure Climb/Descent VariationsA-7
Figure F-1. M aintain Current SpacingF-7
Figure F-2. C apture Then MaintainF-7
Figure F-3. A chieve-by Then Maintain (Cross)F-8
Figure F-4. F inal Approach SpacingF-8
Figure G-1. C ontroller Identifies CAS-A TTF AircraftG-5
Figure G-2. C ontroller Issues Instruction to Follow the Designated Traffic Along With
Approach ClearanceG-6
L ist of Tables
Table 4-1. Aircraft Identification Transmission Examples4-17
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 ProcedureA-13
Table A-3. C ontroller Free Text Controller-Pilot Data Link Communication Message
Set for In-Trail ProcedureA-14
Table F-1. C learance Element FormatsF-6
Table F-2. I nterval Management Clearance Types SummarizedF-9
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.
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.
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.
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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.
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
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).
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).
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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
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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.