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3.3.3 Maneuvering Opposite to an RA.
3.3.3.1 Maneuvers or lack of maneuvers that result in a vertical speed opposite to the RA could result in a collision with the threat aircraft.
3.3.3.2 The threat aircraft may also be operating ACAS II, and it may maneuver in an unexpected direction while responding to a coordinated RA that has been coordinated with own-ship ACAS II.
3.3.3.3 ATC may not be communicating or providing separation service with the threat aircraft. ATC may have less up-to-date altitude data than ACAS II.
ATC does not know if an RA is generated unless notified by the flightcrew. It is possible for ATC to unknowingly issue instructions that are contrary to an RA. When one aircraft in an encounter maneuvers opposite to the RA and the other aircraft maneuvers as indicated by a coordinated RA, the collision risk increases. Flightcrews are advised not to maneuver contrary to the RA based solely upon ATC instructions.
3.4 ATC Clearances and Instructions.
3.4.1 ATC Instructions During an RA.
3.4.1.1 If an RA occurs concurrently with ATC issuing a climb or descend clearance, flightcrews are advised to comply with the RA even if it differs from the ATC climb or descend instruction.
3.4.1.1.1 ACAS II may be coordinating the RA with another ACAS II aircraft. ATC is not automatically informed of RAs. Midair collisions have resulted involving two aircraft operating ACAS II, where one flightcrew complied with the RA while the other complied with ATC instructions.
3.4.1.1.2 For Precision Runway Monitor (PRM)/High Update Rate Surveillance (HURS) close parallel approaches, the Attention All Users Page (AAUP) will state, “TCAS during breakout: Follow TCAS climb/descend if it differs from ATC, while executing the breakout turn.”
3.4.1.2 If an RA requires maneuvering contrary to right-of-way rules, cloud clearance rules for VFR, or other such criteria, flightcrews are advised to comply with the RAs to resolve the immediate traffic conflict.
3.4.1.3 If an RA maneuver is inconsistent with the current clearance, including altitudes published on arrival/approach/departure procedures, respond appropriately to the RA. Since ACAS II tracks all aircraft operating transponders in the vicinity, responding to an RA assures an avoidance maneuver for that threat aircraft and for other aircraft with altitude reporting transponders.
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3.4.1.4 Flightcrews should keep deviations from regulations, clearances, and instructions to the minimum necessary to comply with an RA. While complying with the RA, if possible, comply with ATC clearances and instructions (e.g., turn to intercept an airway or localizer). Response to a stall warning, windshear warning, TAWS “Pull Up” alert, or an RA takes precedence over ATC clearances or instructions, or a requirement to follow a specific route.
3.4.1.5 Each flightcrew that deviates from an ATC clearance or instruction in response to an RA is advised to notify ATC of that deviation as soon as practicable and notify ATC when clear of conflict and returning to the previously assigned or amended clearance.
3.4.1.6 When a flightcrew informs a controller that they are responding to an RA, controllers are not to issue control instructions that are contrary to the RA procedure. After the controller has been informed of an RA, they may continue to issue control instructions and safety alerts, including terrain, obstructions, and ATC-issued traffic advisories, as appropriate.
3.4.1.7 Once the flightcrew that informed the controller of an RA has begun a maneuver in response to an RA, the controller is not responsible for providing approved separation between the aircraft that is responding to an RA and any other aircraft, airspace, terrain, or obstruction.
3.4.2 Clear of Conflict. When an RA is canceled, the “CLEAR OF CONFLICT” message is heard, and the flightcrew should advise ATC as soon as practicable that they are returning to their previously assigned clearance or should acknowledge any amended clearance issued. The flightcrew is advised to immediately return to their previously assigned clearance and advise ATC, or comply with any amended clearance issued.
3.4.2.1 Responsibility for approved separation resumes for the controller when:
• The flightcrew returns to the assigned altitude,
• The flightcrew informs the controller that the RA maneuver is complete and approved separation is met, or
• The flightcrew has executed an amended clearance and approved separation is reestablished.
3.5 Communicating an RA to ATC. To keep all parties on the frequency informed during an RA maneuver, radio communication should be in common phraseology. All transmissions should contain the name of the ATC facility, aircraft identification, and that they are responding to an RA. Communicating an RA is not required if the flightcrew complies with the RA while maintaining compliance with ATC clearances and instructions.
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3.5.1 RA Generated That Affects an ATC Clearance.
3.5.1.1 When a flightcrew receives a new clearance that is subject to a preventive RA
(e.g., “Do Not Climb, Do Not Climb”) that will not allow the flightcrew to comply with clearance instructions, the flightcrew is advised to inform ATC by stating, “[name of the ATC facility], [aircraft identification], TCAS RA, unable to comply” (e.g., “Milwaukee Approach, Skyway 123, TCAS RA, unable to comply”).
3.5.1.2 When a flightcrew receives a corrective RA to either climb or descend from their assigned altitude, or the RA otherwise affects the ATC clearance, the flightcrew is advised to inform ATC when beginning the excursion from the assigned clearance or as soon as workload allows. Flightcrews are advised to inform ATC by stating, “[name of the ATC facility], [aircraft identification], TCAS RA” (e.g., “Washington Departure, Hagar 55, TCAS RA”).
3.5.2 Clear of Conflict. When the RA is clear, the flightcrew should advise ATC that they are returning to their previously assigned clearance or a subsequent amended clearance.
Inform ATC by stating, “[name of the ATC facility], [aircraft identification], clear of conflict, returning to [assigned altitude]” (e.g., “Chicago Center, Freedom 456, clear of conflict, returning to Flight Level 410”).
4-1 CHAPTER 4. ACAS REPORTS
4.1 Pilot Reports. All unusual ACAS events should be reported and investigated. The reports will help to identify potential technical deficiencies and prompt regulators to take appropriate action.
4.1.1 Mandatory Report. When operating under IFR, and an aircraft experiences an RA where compliance with the RA is necessary to avert a substantial risk of collision, a report to the National Transportation Safety Board (NTSB) is required per 49 CFR § 830.5.
4.1.2 ATC Query. Upon query from ATC, make radio or telephone communication as appropriate to complete an ATC Mandatory Occurrence Report (MOR) after a response to an RA per FAA Order JO 7210.632, Air Traffic Organization (ATO) Occurrence Reporting.
4.1.3 Near Midair Collision (NMAC) Reports. An NMAC is defined in the AIM as an incident associated with the operation of an aircraft in which a possibility of collision occurs because of a proximity of less than 500 feet to another aircraft, or a report is received from a pilot stating that a collision hazard existed between two or more aircraft.
Flightcrews should be aware that there is no requirement to submit an NMAC report solely due to an ACAS event and that an ACAS report does not constitute an NMAC report.
4.1.3.1 It is the responsibility of the flightcrew to determine whether an NMAC did occur and, if so, to initiate an NMAC report.
4.1.3.2 Flightcrews involved in NMAC occurrences are urged to report each incident immediately by radio or telephone to the nearest FAA ATC facility or Flight Service Station (FSS).
4.1.3.2.1 Be specific, as ATC will not interpret a casual remark to mean that an NMAC is being reported.
4.1.3.2.2 The pilot should state, “I wish to report a near midair collision.”
4.1.4 FAA Hotline. The FAA Hotline accepts reports related to the safety of the National Airspace System (NAS), violations of 14 CFR, aviation safety issues, and FAA employees or FAA facilities. The FAA Hotline provides a single venue for FAA employees, the aviation community, and the public to file their reports. Visit the FAA Hotline website at https://www.faa.gov/about/office_org/headquarters_offices/aae/progra ms_services/faa_hotlines.
4.1.5 National Aeronautics and Space Administration (NASA) Aviation Safety Reporting System (ASRS) Reports. A flightcrew that experiences a significant event regarding ACAS or collision hazards may file ASRS reports at their discretion at https://asrs.arc.nasa.gov.
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4.1.6 Aviation Safety Action Program (ASAP). If a flightcrew that experiences a significant event regarding ACAS or collision hazards is part of an organization that cooperates in an ASAP, it is recommended that the flightcrew file a report to the Event Review Committee (ERC). Some organizations may not have an ASAP but may offer a similar voluntary safety reporting structure.
4.1.7 O perator Reports . Reports, as specified by the operator, concerning ACAS anomalies, procedural difficulties, or system failures are typically made by flightcrews, and may include the following:
• Pilot/observer questionnaire;
• Logbook entry and Aircraft Communications Addressing and Reporting System (ACARS); or
• Other records used by that operator, such as a captain’s report. See Appendix D, ACAS Resolution Advisory (RA) Report, for details on suggested information to include.
4.2 FAA Response to Pilot Reports of ACAS Events.
4.2.1 FAA Investigations. The FAA will not initiate enforcement action solely based on an ACAS event, provided:
• As per 14 CFR requirements, the aircraft was equipped with ACAS, and the equipment was operating at the time of the event, as applicable.
• The flightcrew complied with ATC clearances and instructions per 14 CFR § 91.123 prior to and during the ACAS-related deviation.
• The flightcrew has successfully completed the FAA-approved air carrier ACAS training program, as applicable.
4.3 Manufacturer Reports.
4.3.1 Manufacturer Monitoring and Reporting. Manufacturers are encouraged to develop procedures to ensure effective identification, tracking, and followup of abnormal ACAS-related events, as appropriate. Such procedures should focus on providing useful information to properly assess the importance of ACAS events and following up on information related to specific ACAS events as necessary to keep the industry and the FAA informed of the performance of ACAS in the NAS and in international operations.
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4.3.2 ACAS Manufacturer Reports. ACAS avionics manufacturers report problems found with specific ACAS installations in accordance with established Service Difficulty Report (SDR) procedures. Report generic problems, such as those that may relate to the definition of ACAS algorithms as defined by RTCA DO-185B, Minimum Operational Performance Standards for Traffic Alert and Collision Avoidance System II (TCAS II), and RTCA DO-385A, Minimum Operational Performance Standards for Airborne Collision Avoidance System X (ACAS X) (ACAS Xa and ACAS Xo), to the FAA Aircraft Certification Service (AIR) at 9-AVS-CAS-Issues@faa.gov.
5-1 CHAPTER 5. OPERATOR RESPONSIBILITIES
5.1 Operational Approval. Once the required aircraft and equipment certification activities have been completed, and prior to operating the installed ACAS equipment, aircraft operators operating under the provisions of 14 CFR part 91 subpart K (part 91K), and parts 121, 125, a nd 135 need to obtain operational approval from their assigned Certificate Management Team (CMT). The CMT is composed of the Principal Inspectors (PI) of the responsible FAA Certificate Management Office (CMO) or Flight Standards District Office (FSDO). Operational approval pertains to changes to operational and maintenance manuals, standard operational procedures, Minimum Equipment Lists (MEL), flightcrew training programs, maintenance training programs, and other areas necessary for safe and effective operation of ACAS. ACAS programs are usually approved for each specific aircraft type of an operator. However, programs common to one or more types may receive approval if ACAS program elements are common to different aircraft types, such as the same ACAS or procedures.
Note: A n airworthiness Type C ertificate (TC)/Supplemental Type Certificate (STC) of an ACAS alone does not constitute operational approval for use of ACAS under the provisions of 14 CFR parts 91K, 121, 125, and 135.
5.1.1 A pproval Procedures.
5.1.1.1 PIs will review the programs of an operator using information developed by the Aircraft Evaluation Division (AED). The responsible Flight Standards offices review the training and maintenance programs, operational procedures, MELs, etc., to ensure consistency with criteria specified in the Master Minimum Equipment List (MMEL), Flight Standardization Board Reports (FSBR), Maintenance Review Board Reports (MRBR), and policy guidance from the FAA (e.g., ACs and FAA orders and notices, including FAA Order 8900.1, Flight Standards Information Management System).
5.1.1.2 The FAA reviews, accepts, or approves installations, flightcrew and maintenance training, maintenance programs, MELs, operations manuals, and other ACAS program elements, as required. Issuance of specific Operations Specifications (OpSpecs) for 14 CFR part 121 and 135 Certificate Holders (CH), Management Specifications (MSpecs) for 14 CFR part 91K program managers, or Letters of Authorization (LOA) for 14 CFR part 125 Letter of Deviation Authority (LODA) holders specific to ACAS is normally not required.
Note: OpSpecs may be influenced by ACAS equipage and operation.
Refer to FAA Order 8900.1, Volume 3, Chapter 18, Operations Specifications, for more details.
5.1.2 M anuals and Other Publications . Aircraft Flight Manuals (AFM), operating manuals, maintenance manuals, general policy manuals, and other manuals, publications, or written materials (e.g., operations bulletins that may relate to ACAS use) should be
5-2 appropriately amended to describe ACAS equipment, procedures, and operational policies according to the appropriate regulation.
5.1.3 O perations Manual . If the AFM, Aircraft Flight Manual Supplement (AFMS), or Pilot Guide to the specific ACAS installation is not otherwise provided to the flightcrew while in flight, the operator should incorporate into the operational manual the description of operation, limitations, emergency procedures, normal procedures, and performance considerations. An operator defines how its flightcrews will operate ACAS II and respond to Traffic Advisories (TA) and Resolution Advisories (RA). The topics recommended to be addressed by these procedures include, but are not limited to:
1. P olicy regarding vertical speed reduction near selected altitude or F light Level (FL) when aware of nearby traffic at or approaching an adjacent altitude or FL.
2. Information provided by ACAS.
3. Policies regarding flight path management including autoflight systems, manual flight operations, and display cues to support flightcrew guidance upon an RA.
4. Limitations of maneuvers based on visual acquisition of other aircraft.
5. The proper response to ACAS advisories, including Crew Resource Management (CRM) policies for roles, responsibilities, and callouts.
6. The conditions where RA compliance is required, reflecting guidance published by the State Civil Aviation Authority (CAA).
7. Effects of improper use of ACAS and potential risks of an improper response to an advisory.
8. The return to an Air Traffic Control (ATC) clearance after an RA.
9. The interaction between ACAS and other aircraft systems.
10. Use of various operating modes (i.e., Standby, TA-ONLY, TA/RA) while airborne and on the ground including during emergency operations (i.e., engine failure).
11. ACAS operating conditions that may be unique to their particular route environment
(e.g., barometric altitude set to the atmospheric pressure at aerodrome elevation (or at runway threshold) (QFE)), aircraft (e.g., response to an RA at the maximum certified altitude), procedures, or traffic display and control features.
12. Event reporting requirements and procedures.
13. Operators who have aircraft with ACAS differences in displays, controls, or procedures, or that are involved with interchange operations, and how the operator accounts for ACAS differences. Accomplish this as part of an approved differences training program, or as otherwise specified in applicable FAA FSBRs concerning crew qualification pertaining to a particular airplane type.
5.1.4 M MEL/MEL. Operators formulate necessary ACAS revisions to the MELs for each aircraft type. MEL revisions are to be consistent or more restrictive than the FAA MMEL established for each aircraft type and current Policy Letters (PL) (e.g., PL-32, Traffic Alert and Collision Avoidance System (TCAS)).
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5.1.4.1 Refer to FAA Order 8900.1, Volume 4, Chapter 4, Section 3, MEL Requirements for 14 CFR Parts 91K, 121, 125, 125 LODA, and 135 Operations, for more details on the approval of MELs.
5.1.5 Maintenance Manual. Maintenance manual procedures for ACAS receive approval or acceptance as part of an operator’s initial maintenance program approval or as a revision to that program.
5.1.5.1 This includes, but is not limited to, addressing installation; modification;
correction of reported system discrepancies; MEL relief; return-to-service authorizations; and procedures for testing installed transponders and automatic pressure altitude reporting equipment on the ground in such a way that false aircraft are not generated in airborne ACAS (e.g., shielding of the transponder antennas).
5.1.5.2 The ACAS maintenance procedures of the operator should be consistent with the maintenance procedures of the ACAS or aircraft manufacturer.
5.1.5.3 ACAS maintenance procedures should include procedures to avoid unnecessary ACAS advisories due to transponder testing on the ground. Refer to AC 43-6, Altitude Reporting Equipment and Transponder System Maintenance and Inspection Practices, and Safety Alert For Operators (SAFO) 17002, Improper Transponder and Automatic Dependent Surveillance-Broadcast (ADS-B) OUT Equipment Testing.
5.1.5.3.1 The following ACs provide more detailed information and guidance concerning the proper procedures to follow when conducting operational testing of ACAS II, Automatic Dependent Surveillance-Broadcast (ADS-B), and transponders:
• AC 20-151, Airworthiness Approval of Traffic Alert and Collision Avoidance Systems (TCAS II), Versions 7.0 and 7.1 and Associated Mode S Transponders.
• AC 20-165, Airworthiness Approval of Automatic Dependent Surveillance - Broadcast OUT Systems.
• AC 20-172, Airworthiness Approval for ADS-B In Systems and Applications.
• AC 43-6, Altitude Reporting Equipment and Transponder System Maintenance and Inspection Practices.
5.1.6 Mai ntenance Training . To properly implement ACAS-related maintenance programs, an operator should provide adequate ACAS training of maintenance personnel in accordance with the appropriate regulations.
5.1.7 F lightcrew Training Manual . Air carriers should ensure appropriate flightcrew ACAS training. Training for ACAS II should include both ground and flight (e.g., flight
5-4 simulator) and should address any significant issues identified by operating experience, system changes, procedural changes, or unique characteristics, such as the introduction of a new aircraft, display system, or operations in airspace where high numbers of TAs and RAs have been reported. The flightcrew should demonstrate knowledge of ACAS concepts, systems, and procedures. The flightcrew should demonstrate proficiency in cognitive, procedural, and motor skills necessary to properly respond to ACAS.
5.1.7.1 There are no formal ACAS flightcrew evaluation requirements for flight testing or checking. An instructor should accomplish an evaluation of ACAS objectives during training. Operators should include routine ACAS operations in all evaluation environments, and check pilot/examiners should include ACAS as a routine discussion item.
5.1.7.2 ACAS knowledge training is typically conducted in a classroom environment.
The knowledge demonstrations may be met by successfully completing written tests or providing correct responses to Computer-Based Training (CBT) questions. Combinations of these methods may be used if the required body of knowledge is completely covered.
5.1.7.3 ACAS maneuver training instructs flightcrews how to properly respond to ACAS displayed information. TAs and RAs are most effective when accomplished in a flight simulator equipped with a traffic display and controls similar in appearance and operation to those in the aircraft. Alternatively, the required maneuver can be carried out by means of an interactive computer-based trainer with a traffic display and controls similar in appearance and operation to those in the aircraft. This interactive computer-based trainer should depict scenarios where real-time responses are to be made. Line-Oriented Flight Training (LOFT) programs may be enhanced by interaction with ACAS. In addition, LOFT programs should consider proper crew vigilance for aircraft that may not be equipped with and operating a transponder or are non-altitude reporting aircraft. Advisories accomplished during LOFT are creditable toward first-time or recurrent qualification. Operators should ensure that their instructors could select all the required RA scenarios on their training devices at any applicable time
(e.g., own-ship above 1,000 feet for an RA) during a simulator session.
5.1.7.4 CRM programs should address effective teamwork, including conducting effective preflight briefings on how to react to ACAS advisories and the proper reaction to a TA and an RA by the Pilot Flying (PF) and the Pilot Monitoring (PM).
5.1.7.5 First-time ACAS training should be accomplished for each ACAS-equipped aircraft type that a pilot is assigned. An operator may accomplish first-time ACAS qualification as a standalone module of ground and flight training or combined with initial, transition, or upgrade ground and flight training programs with the appropriate differences training.
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5.1.7.6 An operator may accomplish recurrent ACAS training during recurrent ground and flight training. Recurrent ground training will be a standalone module. However, ACAS will be fully integrated with the recurrent flight training.
5.1.7.7 For recurrent training, it is recommended that flight training include responses to all RA types. Recurrent training is desirable in a Flight Training Device (FTD) or a simulator approved for the maneuvers. See Appendix B, Sample ACAS Ground and Flight Training Program, for a sample training program.
5.1.8 C ontinuing Operator Responsibilities . After operational approval has been obtained, operators have the following general responsibilities regarding ACAS:
5.1.8.1 Analyzing the implementation of ACAS, revisions to policies and procedures, and identifying hazards, changes in the operational environment, or ineffective risk controls.
5.1.8.2 Using a Safety Risk Management (SRM) program as part of a Safety Management System (SMS) to assess whether the risk is acceptable for permitting procedures such as the use of TA-ONLY mode during operations.
See Appendix C, Safety Management System (SMS) Considerations for ACAS II TA-ONLY Mode Operations.
5.1.8.3 Monitoring and auditing of the operational environment to detect changes needed to processes and procedures, including training, checking, and maintenance programs to ensure their correctness, pertinence, timeliness, and effectiveness.
5.1.8.4 Communicating to operator personnel, as appropriate, when hazards or changes to policies and procedures are identified.
5.1.8.5 Ensuring all ACAS events reported to the operator are assessed.
5.1.8.6 Ensuring all required maintenance reports are completed and assessed for hazards.
5.1.9 Operator ACAS Event Reporting.
5.1.9.1 Operators are encouraged to develop procedures to ensure effective identification, tracking, and followup of significant ACAS-related events, as appropriate. Such procedures should focus on providing useful information to:
• Properly assess the importance of ACAS events.
• Follow up on information related to specific ACAS events, as necessary.
• Keep the industry and the FAA informed of the performance of ACAS in the National Airspace System (NAS) and in international operations.
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5.1.10 Operator Maintenance Personnel Reports. Maintenance personnel are advised to report ACAS problems that relate to system performance, manufacturers, and/or vendors to the appropriate Principal Avionics Inspector (PAI).