Appendix A A-6
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 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
Appendix A A-7 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, In-Trail Procedure Climb/Descent Variations, 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, he or she 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.
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
Appendix A A-8 distance are different. Consequently, a lack of understanding could lead the flightcrew to misidentify the correct reference aircraft(s) 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 unnecessarily 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 part 119, § 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.
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
Appendix A A-9 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)-C195a, Avionics Supporting Automatic Dependent Surveillance-Broadcast (ADS-B) Aircraft Surveillance Applications (ASA), or later, or as approved for ITP by the Administrator.
• Installation complies with Advisory Circular (AC) 20-172, Airworthiness Approval for ADS-B In Systems and Applications.
• 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-C195a or later, 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 B050 paragraph 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 of the proposed region(s) of operation.
A.6.2.5 Operation Manuals and Checklists. The certificate holder/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:
Appendix A A-10
• 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;
• 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
Appendix A A-11 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 part 91 operations. However, as the pilot is responsible for flight planning, the pilot should consider these items prior to flight.
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 1x10E-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
Appendix A A-12 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 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.
Appendix A A-13 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 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.
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 managing spacing and avoiding wake turbulence 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 traffic information does not replace any traffic advisories (TA) and/or Resolution Advisories (RA) provided by the aircraft’s Traffic Alert and Collision Avoidance System (TCAS). RA response is still based on the TCAS display and approved procedures.
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 aircraft weight categories.
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.
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, incorporate two 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 1.4 nautical miles (NM) or, in some installations, when the CAVS system detects a predetermined excessive closure to the TTF. 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 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 displays 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 more precisely manage their spacing and closure.
Appendix B B-3
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 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 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 it 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 interval 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, or a system approved by the Administrator intended for use in CAVS. For guidance on the installation of CAVS equipment, refer to Advisory Circular (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 part 119, § 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.
Appendix B B-4 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 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, or as approved for CAVS by the Administrator.
• Installation complies with guidance contained in AC 20-165 and AC 20-172.
• 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, or as otherwise approved by the Administrator, for CAVS operations.
B.7.2.3 Operation Manuals and Checklists. The certificate holder/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.