FAA En Route Domestic CPDLC—Operational Background Information for Pilots
Disclaimer: ALPA has developed this webpage for informational purposes only, and it is not intended to supersede any company training, guidance, or other material. In case of any conflict, company-provided information should be considered to have primacy. FAA has also published additional guidance on the use of CPDLC on the Harris Corporation website. If you have any questions, please contact ALPA Engineering and Air Safety at EAS@alpa.org or 800-424-2470.
The Federal Aviation Administration (FAA) is in the process of deploying controller-pilot data link communications (CPDLC) in U.S. en route domestic airspace.
CPDLC allows air traffic controllers to send data link clearances and instructions to pilots in domestic airspace, including climbs, descents, reroutes, and handoffs between ATC sectors in the En Route Center (ARTCC) environment. In addition to flight efficiency benefits from streamlined communications, CPDLC is expected to enhance safety as reroutes are provided in a form that allows for loading directly into the FMS, reducing the risk of typing errors or fix name confusion.
For pilots with international or oceanic experience with CPDLC, the service is largely the same in domestic airspace. However, there are some areas, especially concerning LOGON, that are unique to the United States. Also, because the domestic en route environment is more tactical than the oceanic environment, pilots should expect to receive both CPDLC and voice communications routinely on all flights.
ALPA will keep this page up to date with the latest information for pilots as the system is deployed.
- If you do not understand or are not absolutely clear on the interpretation or application of a CPDLC clearance, do not accept it (select REJECT/UNABLE), and then verify by voice.
- Follow company training and procedures for use of CPDLC.
- Review the dispatch release and MEL to ensure that the aircraft is qualified to perform CPDLC.
- Respond to all CPDLC messages received, including those that only require an acknowledgement (ROGER/ACCEPT).
- All CPDLC messages will be normal operational ATC clearances, and CPDLC messages do not require voice readbacks unless requested by ATC (acknowledgement is through the ACCEPT/WILCO or REJECT/UNABLE response via CPDLC).
- Note that clearances given by voice by ATC still require voice readbacks.
En Route CPDLC Site Activation Map
The latest map showing the status of CPDLC deployment at each FAA Air Route Traffic Control Center is available online from Harris Corp.
En Route Deployment Schedule
The following is the latest map showing the start of 24-hour, 7 days per week en route services. We will keep this map up to date as there are schedule changes.
Dates for the start of 24/7 services (Expanded DFV)
NOTE: Limited services may be received earlier.
CPDLC is currently in use 24/7 at Indianapolis and Kansas City ARTCCs.
The above map reflects the replanned airborne CPDLC deployment schedule, which was needed after the partial government shutdown in January 2019. Note that later sites may deploy earlier if opportunities are found to accelerate deployment.
Logon Procedures and Connection Issues
An active connection established with KUSA (Boeing implementation). Do not relogon if “ACT CTR” = KUSA
- Flight crews should confirm on the ATC LOGON/STATUS page that you have an active connection with KUSA in level flight after departure and relogon to KUSA only if a connection does not exist.
- Flight crews may (very occasionally) see a “NO COMM” or similar message while in flight; in this case, you should go to the ATC LOGON/STATUS page and see whether an active connection is still established with KUSA. If there is a connection, then no action is required. This indicates a temporary loss of radio link, but the connection remains alive.
Technical Background: If a relogon is attempted while a connection with KUSA is already established, the ground system can only assume that an avionics reset has occurred, and the connection must be completely torn down on both ends to ensure safety. This will require additional ATC action and voice confirmation, followed by a third logon to reestablish CPDLC. Therefore, flight crews should be careful to only log on if there is no active connection with KUSA.
Once a connection is established with an ATC facility, the aircraft may receive a welcome message. Make sure you ACCEPT or ROGER this message (red arrow):
Controller Handoffs—Monitor and Contact
While originally planned for initial implementation, use of the “MONITOR [facility] ON [frequency]” handoff message (e.g., “MONITOR KANSAS CITY CENTER ON 123.875”) will be delayed for several months due to procedural issues uncovered during testing.
For the time being, all handoffs between ATC sectors will use CONTACT (e.g., “CONTACT KANSAS CITY CENTER ON 123.875”).
Per current voice procedures, CONTACT requires the pilot to check in on the new frequency via voice. Be sure to ACCEPT/ROGER the CONTACT message after tuning the VHF radio.
Loading Routes with SIDs and STARs
In general, receiving a route clearance revision via data comm will be loadable into the FMS with a button press (“autoload”). While this is of great convenience and enhances safety by eliminating typographic errors, there are two exceptions that pilots should be aware of:
- SIDs/DPs: Due to limitations in FAA ground systems, when receiving a clearance revision prior to departure, all standard instrument departures (SIDs)/departure procedures (DPs) need to be inserted manually by the pilot:
Airbus-style implementation (this example is split across pages 1 and 2)
- STARs/Arrivals: Due to limitations in FAA ground systems, procedure designs, and/or avionics limitations, SOME aircraft may not be able to load Standard Terminal Arrivals (STARs) or Arrivals when receiving a revision while en route. In these cases, pilots will need to manually insert the STAR. This is prompted by free text in the cockpit “MANUALLY LOAD ARRIVAL”:
Note that this does not apply to all aircraft; for example, B-737s are able to load STARs.
Pilot Use of Free Text or “Due to” Reasons
In general, you should not use FREE TEXT to respond to ATC, as this feature is not planned to be fully implemented on the ground side. If free text is sent, in most cases the ground system will return an error message, and the message is not delivered to the controller. The only exception is for the defined EMERGENCY pilot downlink messages.
Similarly, when using a “DUE TO” reason, do not select any options except for “DUE TO WX” or “DUE TO PERFORMANCE.” Do not use free text either. An error message will be returned in most cases.