5.3.5 Data Must Match Flight Plan. To avoid an automatic rejection of the logon/notification request, the pilot must ensure the flight-specific information entered into the aircraft system is the same as the corresponding details filed in the flight plan.
5.3.6 Possible Reasons for Failed Logon/Notification. The following are possible reasons for receiving an indication of logon/notification failure:
1. Logon/Notification information does not exactly match flight plan
(e.g., incorrect tail number and/or call sign/flight ID);
2. Ground or air system anomaly;
3. Data corruption;
4. Suspected duplicate aircraft registration;
5. Aircraft intentionally blocked from logging on/notifying (i.e., on blocked list due to problem reports with the aircraft); and/or
6. There is no flight plan for the flight or the flight plan did not transfer from one ATSU to the next.
5.3.7 Failure of Data Link Communication Connection. When failure of a data link communication connection is detected (downlink message fails to send), the pilot should terminate the connection and then initiate a new logon/notification with the current ATSU. If another failure occurs, revert to voice communication.
5.3.8 Logon/Notification Response. The logon/notification response message provides information to the aircraft system concerning whether:
1. The logon/notification request was successful (e.g., could be correlated with a flight plan); or
2. The logon/notification request was unsuccessful (e.g., could not be correlated with a flight plan).
5.4 En Route. Normally, response to CPDLC messages should be via CPDLC and response to a voice message should be via voice. However, if a CPDLC message is unclear or conflicting, always clarify with voice and then close the CPDLC dialog.
5.4.1 Contact or Monitor Message. A CONTACT (UM117) or MONITOR (UM120) message instructs the pilot to change to the specified frequency and may include a position or time for when to change to the new frequency. Use of a CONTACT or MONITOR message is as follows:
1. When a MONITOR (UM120) message is received, the pilot should change to the specified frequency upon receipt of the instruction or at the specified time or position. The pilot should not establish voice contact on the frequency.
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2. When a CONTACT (UM117) message is received, the pilot should change to the specified frequency upon receipt of the instruction or at the specified time or position, and establish voice contact on the frequency.
5.4.2 Waypoint Sequencing. The pilot should ensure waypoints are sequenced correctly. If an aircraft passes abeam a waypoint by a distance greater than the aircraft flight management system (FMS) waypoint automatic sequencing parameter, the pilot should manually sequence the waypoints in the FMS. If the pilot does not sequence the waypoints, incorrect information will be contained in ADS-C reports and CPDLC position reports; the next waypoint in these reports will actually be the waypoint that the aircraft has already passed. This may result in a timing error or out of conformance indication on the Air Navigation Services Providers (ANSP) ground system.
5.4.3 Multi-Part Messages. If pilots are unable to comply with any portion of a multi-part message, “UNABLE” (DM1) the entire message. Additionally, pilots should avoid sending multiple requests to the ATSU in a single message.
5.4.4 CPDLC Connection Failure. If a CPDLC dialogue is interrupted by a data link service failure, expect the controller to recommence the entire dialogue by voice communication.
When the controller recognizes a failure of the CPDLC connection, the controller will instruct the pilot to terminate the connection and then initiate another logon/notification.
See Table 5-1, CPDLC Connection Failure Responses, for the voice phraseology in response to a connection failure.
Table 5-1. CPDLC Connection Failure Responses Controller/Pilot Response Controller (or radio operator) CPDLC FAILURE.
DISCONNECT CPDLC THEN LOGON TO [facility designation] Pilot DISCONNECTING CPDLC WITH [facility designation]. LOGGING ON TO [facility designation] Note: Additional voice phraseology is available in Appendix E, Voice Phraseology.
5.5 Voice Monitoring. Pilots must continuously monitor VHF or high frequency (HF) as appropriate and/or maintain a Selective-Calling System (SELCAL) watch.
5.5.1 Pilot Response. As with voice communication, pilots should respond as soon as possible to all data link communication messages (e.g., ROGER (DM3)/WILCO (DM0), UNABLE (DM1), or STANDBY (DM2)). If more time is needed to make a decision and respond, select standby (“STBY”).
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5.6 Free Text Messages. Free text messages should only be used when a standard message element does not exist or is inadequate. When sending a free text message, use standard ATSU phraseology and avoid using non-standard abbreviations. (See Appendix E.)
Note 1: For FANS 1/A implementations, the pilot cannot respond to the free text message element with ROGER (DM3)/WILCO (DM0), UNABLE (DM1), or STANDBY (DM2).
Note 2: When the controller uses free text to ask the crew affirmative/negative questions, the pilot can only respond with ROGER (DM3)/WILCO (DM0), which means they have read and understood the message, but does not answer the question affirmatively. In these cases, the pilot should respond to the question with a separate message (see Appendix E).
5.7 Data Link Communication Failures. The pilot must notify the ATSU as soon as practical of any indications of degraded performance resulting from a failure or loss of connectivity in accordance with 14 CFR part 91, § 91.187. For example, reportable events include:
1. When operating outside of VHF coverage area and the SATCOM data link communication system fails; and
2. When operating in airspace where ATSU surveillance services are provided and the VHF data link communication system fails.
Note: Timely notification is appropriate to ensure the ATSU has time to assess the situation and apply a revised separation standard, if necessary.
5.7.1 Failure of Automatic Transfer. If an automatic transfer of the CPDLC connection does not occur at the boundary (CDA to NDA), the pilot should contact the transferring ATSU by sending a CPDLC TRANSFER FAILURE (DM 67) message or voice equivalent, advising them the transfer has not occurred. If this does not resolve the situation, the pilot should logoff/disconnect and logon/notify the NDA. Revert to voice if still unable to logon/notify NDA.
5.7.2 Actions and Phraseology for Data Link Communication Failure. In the event of an aircraft data link communication system failure, the pilot should revert to voice and notify the ATSU of the situation. For example, for a CPDLC failure, the pilot should use the voice phraseology, “CPDLC failure, continuing on voice,” as shown in Table E-1, Voice Phraseology Related to Controller-Pilot Data Link Communication (CPDLC) From Pilot. The pilot continues to use voice until the functionality of the aircraft system can be reestablished.
5.8 ADS-C. Normally, the pilot should leave ADS-C armed for the entire flight. However, in airspace where ADS-C is available, if the pilot switches ADS-C off for any reason, or they receive indication of avionics failure leading to loss of ADS-C, the pilot should advise ATC and follow alternative procedures.
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5.8.1 Airspace Where ADS-C Is Not Available. In airspace where ADS-C is not available, the pilot may switch ADS-C off to cancel inadvertent ADS-C connections. In such cases, the pilot should ensure the ADS-C is armed when reentering airspace where ADS-C is again available.
5.8.2 Emergencies. The pilot may activate the ADS-C emergency mode, which changes all existing ADS-C periodic contracts from normal mode to emergency mode and creates emergency mode ADS-C periodic contracts on any ADS-C connections that do not have a periodic contract already in place. The pilot may also activate ADS-C emergency mode by sending a “MAYDAY MAYDAY MAYDAY” (DM56) or “PAN PAN PAN” (DM55) CPDLC message. ADS-C emergency mode may be deactivated by the ATSU or by the pilot sending a “CANCEL EMERGENCY” (DM58) CPDLC message. In emergencies, pilots may revert to voice communication when able.
5.9 Exiting CPDLC and ADS-C Areas. The ATSU should automatically logoff/disconnect data authority approximately 15 minutes after exiting CPDLC and/or ADS-C areas.
After 15 minutes, if aircraft equipment permits, the pilot should ensure there are no active CPDLC or ADS-C connections. Ensuring connections are not active eliminates the possibility of inadvertent or inappropriate use of the connections.
5.9.1 Contact Current ATSU. The pilot should contact the current ATSU unit prior to the manual termination of any ADS-C contract. This applies even when outside the applicable ATSU and the pilot logs off/disconnects ADS-C because it did not logoff/disconnect 15 minutes after leaving ADS-C airspace.
5.9.2 Connection Termination Failed. In the event the connection termination has failed, the pilot should contact the ATSU via voice or any other appropriate means.
5.10 Logoff/Disconnect. Prior to logoff/disconnect, the pilot should ensure there are no unresolved or open messages. The pilot will logoff/disconnect and confirm CPDLC connection is terminated and continue with voice communication.
Note: Pilots should wait at least 10 minutes after landing before initiating a CPDLC-Departure Clearance (DCL) logon/notification to ensure En Route Automation Modernization (ERAM) and Tower Data Link Services (TDLS) have enough time to clear previous flight information.
5.10.1 U.S. Domestic Logoff/Disconnect. Logoff/disconnect should automatically occur approximately 5 minutes after departure for DCL services. Do not logoff/disconnect until ATC terminates the session. If proceeding to international or oceanic and remote continental airspace and CPDLC services are not terminated, then manually logoff/disconnect prior to a new logon/notification.
Note: When KUSA is active as the domestic U.S. single data authority, CPDLC services will not automatically terminate after departure. Aircraft leaving U.S. airspace must logon/notify the next appropriate NDA.
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5.10.2 International and Oceanic and Remote Continental Logoff/Disconnect. The ATSU should automatically logoff/disconnect data authority approximately 15 minutes after exiting CPDLC and/or ADS-C areas.
Note: For transitions between data link communication systems (i.e., FANS to ATN), follow OEM procedures for logon/notification/logoff/disconnect requirements specific to your avionics system.
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CHAPTER 6. PERFORMANCE MONITORING
6.1 Performance Monitoring. With the implementation of performance based systems, monitoring of those systems ensures compliance. Monitoring provides a higher level of confidence the operational system will continue to meet the Required Communication Performance (RCP)/Required Surveillance Performance (RSP) specification. Operators should incorporate a performance monitoring process and must participate in performance monitoring which includes reporting and addressing problems. The goal of monitoring data link communication performance is to:
• Maintain safe and efficient operations;
• Determine continued compliance and interoperability;
• Investigate problems; and
• Share lessons learned.
Note: There are no established RCP/RSP standards in U.S. domestic airspace as of the publication date of this AC. As Controller-Pilot Data Link Communication (CPDLC) is introduced into en route operations for U.S. domestic airspace, RCP standards will be published.
6.2 Oceanic and Remote Continental Airspace.
6.2.1 FAA Data Collection. The FAA, along with other Air Traffic Service Units (ATSU), has been monitoring CPDLC and Automatic Dependent Surveillance-Contract (ADS-C) transactions since 2009. Analysis of Actual Communications Performance (ACP) for the CPDLC transactions and Actual Surveillance Performance (ASP) for the ADS-C downlink messages (DM) are accomplished on a semi-annual basis with an emphasis on the nominal continuity (95 percent) requirements associated with safety.
6.2.2 RCP Performance Analysis. Data analysis of ACP, including the Actual Communication Technical Performance (ACTP), is compared against RCP standards (see Tables 2-4 through 2-9) to determine whether the CPDLC performance is adequate.
6.2.3 RSP Performance Analysis. ASP is compared against RSP standards (see Tables 2-10 through 2-15) to determine whether surveillance performance is adequate. ASP analysis is based on the calculation of delivery time of the ADS-C periodic and event reports between the aircraft and the ATSU ground system.
6.2.4 Evaluating Operational and Nominal Transaction Times. ACP and ASP are evaluated using operational (99.9 percent) and nominal (95 percent) continuity criteria. Observed ACP and ASP must meet or exceed the nominal 95 percent continuity requirements.
Note 1: If ACP/ASP does not meet the nominal continuity, the operator will be notified and should not continue data link operations at the associated performance level until the issue is resolved (see paragraphs 6.4 and 6.5).
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Note 2: If ACP/ASP does not meet the operational continuity 99.9 percent, the operator is notified to investigate and initiate corrective action. The nominal performance 95 percent is still sufficient for data link communication performance.
6.3 Performance Website. Operators may obtain a Pass/Fail/insufficient data monitoring performance report for their aircraft from the FAA Performance-based Communication and Surveillance (PBCS) Monitoring website.
6.4 Substandard Performance. Operators must address substandard performance whether the source of that report is from the operator’s own monitoring process, Communication Service Provider (CSP), FAA, or a foreign authority. Operators can view aggregate performance observed within FAA oceanic airspace from the PBCS monitoring website in the above paragraph. If the result of the report is “Fail,” the operator should follow the directions on the website to request further details and a corrective action plan. With a “Fail” report, operators may continue to operate at a less stringent performance level
(i.e., RCP 240 to RCP 400) provided they file the appropriate performance flight plan designator.
6.5 Corrective Aircraft Action. The operator may return to the performance stated in their statement of compliance (SOC) provided the corrective action plan is completed.
6.6 Data Link Performance Eligibility. As stated in paragraph 3.3.5, RCP and RSP performance monitoring data should be included to quantify data link eligibility.
If performance monitoring data is insufficient, then the SOC will be the initial basis for compliance with continued monitoring.
6.7 Procedures to Report Problems. The operator should establish procedures to report problems to the regional PBCS monitoring entities identified in Aeronautical Information Publications (AIP) (or equivalent publications) associated with the route of flight on which the problem occurred (see Chapter 8, Reports).
6.8 Performance Monitoring in U.S. Domestic Airspace. Reserved.
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CHAPTER 7. TRAINING
7.1 Training Documentation.
7.1.1 Part 91 Operator Training. Part 91 operators must be proficient with the procedures and operations associated with the use of data link communication systems in accordance with their Airplane Flight Manual (AFM) and AFM Supplement if applicable. Part 91 operators should be knowledgeable with the procedures and operations as shown in paragraphs 7.4 and 7.5.
7.1.2 Parts 91 Subpart K (Part 91K), 121, 125, and 135 Operator Training. Part 91K, 121, 125, and 135 operators should have a training program addressing the operational practices, procedures, and training items related to data link communication operations (e.g., initial, upgrade, or recurrent training for pilots, operational control personnel, and maintenance personnel). If criteria for training or checking are other than as specified in this AC, the criteria may be found in Flight Standardization Board (FSB) reports applicable to a particular aircraft type.
Note: A separate training program is not required if data link communication training is integrated in the current training program. However, the applicant must identify the training elements from this AC within the existing training program.
7.2 Objectives. Operators should include the following objectives to ensure appropriate pilot data link communications qualification:
• Provide necessary pilot knowledge of data link performance-based communication and surveillance concepts, systems, procedures, and skills to properly respond to data link communication clearances and advisories; and
• Identify human factor issues specific to pilot operation and interaction with the communication software, hardware, and operating environment (e.g., head-down time, situational awareness, or loss of pilot response time in the Required Communication Performance (RCP) specification).
7.3 Ground and Flight Training.
7.3.1 Pilot Knowledge/Training. Parts 91K, 121, 125, and 135 operators should maintain training syllabi (e.g., initial, upgrade, or recurrent) and other appropriate materials including operational practices and procedures. Training for other personnel must be included where appropriate (e.g., operational control personnel or maintenance).
7.3.2 Pilot Training. Parts 91K, 121, 125, and 135 operators should ensure their process contains training for pilots on equipment requirements, normal and non-normal operations and procedures, and limits of their data link communication capability.
Pilots must receive data communications training specific to the avionics suite they will be operating. A common type rating does not guarantee the pilot has received training on the data communications equipment installed on a particular aircraft.
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7.3.3 Regulatory Basis. All training must be in accordance with the following where applicable:
1. Part 91K:
• § 91.1073, Training Program: General.
• § 91.1081, Crewmember Training Requirements.
• § 91.1111, Maintenance Training.
2. Part 121:
• § 121.375, Maintenance and Preventive Maintenance Training Program.
• § 121.401, Training Program: General.
3. Part 135:
• § 135.323, Training Program: General.
• § 135.329, Crewmember Training Requirements.
• § 135.433, Maintenance and Preventive Maintenance Training Program.
7.4 Pilot Knowledge Subject Areas. The minimum following subjects should be addressed in an approved curriculum of data link communications academic training during the initial introduction of data link communication systems:
1. Normal pilot response to data link communication messages to include:
ROGER (downlink message (DM) 3)/WILCO (DM0), UNABLE (DM1), or STANDBY (DM2) of a data link communication message;
2. Message elements in the message set used in each environment (e.g., ground, oceanic, en route) including terms, abbreviations, and conventions;
3. RCP/Required Surveillance Performance (RSP) specifications and their performance requirements;
4. Data link communication terminology (e.g., Controller-Pilot Data Link Communication (CPDLC) and Automatic Dependent Surveillance-Contract (ADS-C) reporting contracts);
5. Chart depictions of data link communication services;
6. Implementation of reduced separation with associated data communication system requirements to comply with RCP 240 and RSP 180 or other possible performance requirements associated with their routes;
7. Data link communications system theory (relevant to operational use);
8. Operations involving data link communication services;
9. Nominal and unacceptable performance;
10. Normal and non-normal use;
11. Data link communication events and reporting (see Chapter 8, Reports);
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12. AFM and AFM Supplement limitations;
13. Crew Resource Management (CRM) of independent message verification, discussion, and action (see paragraph 5.2.1);
14. Minimum equipment list (MEL), deferrable items, and procedures;
15. Human factors specific to the operating environment and operation of installed communication equipment; and
16. Proper use of flight plan designators for data link operations in U.S. domestic airspace and, if applicable, in oceanic and remote continental airspace.
Note: For subsequent ground training, only the new, revised, or emphasized items need be addressed.
7.5 Pilot Procedural Training Items. As a minimum, procedural training should include:
1. Proper use of data link communication controls, procedures, and limitations.
2. Logon/notification procedures and reestablishing system operation after loss of network logon/notification.
3. Display features.
4. Weather deviations, offsets, and waypoint sequencing.
5. Advisories and annunciation.
6. Timely and correct responses to data link communication failures.
7. Recognition of data link communications system failures and data link communication issues unique to the air carrier or operator.
8. Appropriate interaction with the Air Traffic Service Unit (ATSU) following data link communication messages that are not acceptable.
9. CRM. Independent message verification, discussion, and action (see paragraph 5.2.1).
10. Understanding, accepting, receiving, rejecting, or canceling messages.
11. Storing and retrieving messages.
12. Loading messages into appropriate controls/displays for use (e.g., flight management system (FMS)) formulating and sending messages.
13. Departures and departure transitions are not included in the loadable route uplink and must be manually entered by the pilot into the FMS when provided in the Departure Clearance (DCL). Refer to the NAS Data Communications Guide.
14. Loading message requests from the FMS (e.g., flight plan waypoints into data link communication for transmission, if applicable).
15. Managing the communications systems.
16. Establishing and terminating system operation.
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17. Switching use of Radio Frequency (RF) media (if this is a pilot-controllable feature).
18. Items particular to an air carrier’s implementation or the uniqueness of its aircraft capability and/or procedures.
19. Applicable message sets, expected transmission times, failure annunciations, constraints, and limitations.
20. CRM in responding to data link communication exchanges.
21. Data link communication modes of operation.
22. Normal and non-normal pilot operating procedures.
23. Conditional clearances and the adherence to certain conditions or restrictions such as changing a flight level based on a time or place.
7.5.1 Credit for Training. Operators may receive credit for existing data link communications training already approved in a different application. For example, an operator may receive credit for training based on previous use of data link communication services, such as on different routes, for a different type of operation, or training conducted by another operator (except for part 121 or 135), training center, or manufacturer.
The principal operations inspector (POI) will determine whether and how much credit an operator should receive, considering whether the training is used in another FAA-approved application and whether the operator has demonstrated the training is relevant to the new application.
7.5.2 Pilot Currency. Once pilots have completed initial data link communication training, pilot currency programs/training should include data link communication elements.
7.6 Dispatcher Training. An aircraft dispatcher, flight follower, or other operational control personnel should not be assigned to duty unless he/she has demonstrated satisfactory data link communication knowledge to the operator. Training should include:
• Proper use of flight plan designators (see Appendix D, Flight Planning);
• ATSU separation criteria and procedures;
• MEL remarks or exceptions based on data link communications;
• Procedures for transitioning to voice communication and other contingency procedures related to the operation in the event of abnormal behavior of the data link communication services;
• Coordination with the ATSU related to or following a special data link communication exceptional event; and
• Contingency procedures to transition to a different separation standard when data link communication services fail.
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7.7 Maintenance Training. Operators should ensure all maintenance personnel receive training on their airplane’s data link communication equipment. Operators unsure of required maintenance procedures for data link communication-related equipment should contact their aircraft manufacturer field service representatives.
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