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
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.
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).
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.
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.
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).
Appendix F F-1 APPENDIX F. INTERVAL MANAGEMENT
CONTENTS Paragraph Page
F.1 PurposeF-3
F.2 BackgroundF-3
F.3 IM DescriptionF-3
F.3.1 IM Description—Ground ComponentF-3
F.3.2 IM Description—Airborne ComponentF-3
F.3.3 Notional PhraseologyF-4
F.3.4 Early FIM AvionicsF-4
F.4 IM TerminologyF-4
F.4.1 Assigned Spacing Goal (ASG)F-4
F.4.2 Cross Point (CP)F-4
F.4.3 Designated TrafficF-4
F.4.4 Flight-Deck Interval Management (FIM) AvionicsF-4
F.4.5 Flight Identification (FLT ID)F-5
F.4.6 Interval Management (IM) AircraftF-5
F.4.7 Interval Management (IM) Clearance TypeF-5
F.4.8 Interval Management (IM) Path MonitoringF-5
F.4.9 Interval Management (IM) SpeedF-5
F.4.10 Interval Management (IM) Speed Compliance MonitoringF-5
F.4.11 Planned Cancellation Point (PCP)F-5
F.4.12 Selected TrafficF-5
F.5 IM Clearance Types DescribedF-5
F.5.1 Clearance Type FormatF-6
F.5.2 Maintain Current SpacingF-6
F.5.3 Capture Then MaintainF-7
F.5.4 Achieve-by Then Maintain (“Cross”)F-7
F.5.5 Final Approach SpacingF-8
F.5.6 IM SuspendF-8
F.5.7 SafeRoute+ DifferencesF-8
F.5.7.1 Maintain Current Spacing and Capture Then MaintainF-8
Appendix F F-2
F.5.7.2 Achieve-by Then MaintainF-9
F.5.7.3 No IM SuspendF-9
F.6 IM ProcedureF-9
F.6.1 ATC Identifies IM PairF-9
F.6.2 ATC Checks FeasibilityF-9
F.6.3 ATC Issues IM ClearanceF-9
F.6.4 IM Flightcrew Reads Back ClearanceF-10
F.6.5 IM Flightcrew Verifies Lead AircraftF-10
F.6.5.1 FLT ID VerificationF-10
F.6.6 FIM Avionics Internal CheckF-10
F.6.7 IM Flightcrew Evaluates IM SpeedF-10
F.6.7.1 Rejected ClearanceF-10
F.6.7.2 Accepted ClearanceF-10
F.6.8 IM Flightcrew Flies IM SpeedsF-10
F.6.8.1 Compliance With IM SpeedsF-10
F.6.8.2 Mandatory Published SpeedsF-11
F.6.8.3 Compliance With Operational or Regulatory Speed RestrictionsF-11
F.6.9 IM CancellationF-11
F.7 Off-Nominal SituationsF-11
F.8 IM Flight PlanningF-12
F.8.1 IM Outside the U.S. NASF-12
F.8.2 FP CodesF-12
F.9 Authorization to Conduct IMF-12
F.9.1 Initial Request for AuthorizationF-12
F.9.2 Documentation to Submit With Formal RequestF-12
F.9.2.1 Request LetterF-12
F.9.2.2 Airplane Flight Manual (AFM) Compliance DocumentationF-13
F.9.2.3 Operation Manuals and ChecklistsF-13
F.9.2.4 Maintenance DocumentationF-13
F.9.2.5 Revision of Minimum Equipment List (MEL)F-13
F.9.2.6 Pilot TrainingF-13
F.9.2.7 Dispatch/Flight Follower TrainingF-14
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
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.
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.
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.”