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.
Appendix G G-1 APPENDIX G. CDTI ASSISTED SEPARATION ON APPROACH
CONTENTS Paragraph Page
G.1 PurposeG-3
G.2 BackgroundG-3
G.3 CAS-A ConceptG-3
G.3.1 CAS-A Concept—Ground ComponentG-3
G.3.2 CAS-A Concept—Airborne ComponentG-3
G.3.3 Notional PhraseologyG-4
G.4 CAS-A TerminologyG-4
G.4.1 Cockpit Display of Traffic Information (CDTI) Assisted Separation
on Approach (CAS-A) AircraftG-4
G.4.2 Cockpit Display of Traffic Information (CDTI) Assisted Separation
on Approach (CAS-A) AvionicsG-4
G.4.3 Designated TrafficG-4
G.4.4 Flight Identification (FLT ID)G-4
G.4.5 Selected TrafficG-4
G.5 CAS-A Communications DescribedG-4
G.6 CAS-A ProcedureG-4
G.6.1 Controller Identifies CAS-A TTF AircraftG-5
G.6.2 Flightcrew Reads Back the Designation InstructionG-5
G.6.3 Flightcrew Verifies TTF AircraftG-5
G.6.3.1 FLT ID VerificationG-5
G.6.3.2 CAS-A Avionics Performs Internal ChecksG-5
G.6.3.3 Flightcrew Confirms TTF Designation With the ControllerG-5
G.6.4 Controller Issues Instruction to Follow the Designated Traffic Along
With Approach ClearanceG-6
G.6.4.1 Accepted CAS-A Instruction to Follow the Designated TTFG-7
G.6.4.2 Rejected ClearanceG-7
G.6.5 Flightcrew Flies Normal Approach ProcedureG-7
G.6.6 CAS-A CancellationG-7
G.7 CAS-A AlertingG-7
G.7.1 Selectable Range IndicationG-7
Appendix G G-2
G.7.2 Minimum Range AlertG-7
G.8 Off-Nominal SituationsG-8
G.9 CAS-A FP CodesG-8
G.10 Authorization to Conduct CAS-AG-8
G.10.1 Initial Request for AuthorizationG-8
G.10.2 Documentation to Submit With Formal RequestG-8
G.10.2.1 Request LetterG-8
G.10.2.2 Airplane Flight Manual (AFM) Compliance DocumentationG-9
G.10.2.3 Operation Manuals and ChecklistsG-9
G.10.2.4 Maintenance DocumentationG-9
G.10.2.5 Revision of Minimum Equipment List (MEL)G-9
G.10.2.6 Pilot TrainingG-9
G.10.2.7 Dispatch/Flight Follower TrainingG-10
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.
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:
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
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
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.
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.
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.
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.
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.
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