Duncan Aviation Outlines Ground Testing of CPDLC, ADS-C and Datalink Systems Using ARINCDirect, Satcom Direct and Honeywell Forge

Duncan Aviation has published a general overview of how pilots and DOMs can test aircraft datalink systems before a scheduled flight. The overview is not detailed procedural instructions; operators are told to consult the AMM or pilot's operating handbook for their datalink system.

Three systems are described. CPDLC (Controller Pilot Data Link Communication) is used to request departure clearances and communicate with ATC while en route. ADS-C (Automatic Dependent Surveillance–Contract) automatically sends position reports to ATC via datalink (VHF, HF or SATCOM). ACARS is an older datalink system that operates on VDL mode A only; it provides weather and ATIS information only, with no CPDLC or ADS-C.

Basic CPDLC connection tests are offered by Collins Aerospace ARINCDirect and Satcom Direct. The pilot selects ATC on the FMS/CDU, enters the flight ID, tail number and a 4-letter test station ID, and should receive an ACCEPTED or similar response on the login/status page. ARINCDirect test station IDs are ARDC and ARDD. Satcom Direct's test station ID is WIFS, with WIFS1 used as the flight ID or call sign. Operators must not use KUSA as the test station: it is the National Single Data Authority (NSDA) for all CPDLC logons and notifications in the United States and is in active operation.

With 24-48 hours' notice, Honeywell Forge (formerly GoDirect) offers more detailed testing with a technical support representative. Collins Aerospace and Satcom Direct also provide detailed testing and technical assistance, with advance notice required. Advanced testing is recommended only for troubleshooting a known problem, changing service providers or after a new installation.

CPDLC should be tested only on the ground. A VHF datalink test may work in a hangar, but a SATCOM link test likely will not. Both VHF and SATCOM should be tested, especially for flights over water.

Datalink systems first try to connect to a VHF ground station unless VHF3 is in voice mode or disabled. Newer systems can connect on any of the three VHF Comms (VDLs), so all three must be in voice mode to test via SATCOM. The CMU pings the listed regional ground stations until it gets a response or times out, which can take several minutes.

Operators planning to fly in EASA airspace must also perform the test on the ATN International datalink network, Link2000+. Other datalink services can be checked by requesting weather products such as SIGMETs, Terminal WX or winds aloft, which verify that the VHF, IRIDIUM or INMARSAT connection is functional. Many AMMs include datalink testing procedures in ATA chapter 23.

Datalink failures tend to surface at the worst moment: at the gate before an oceanic departure, or mid-route when a logon is rejected. A test that can be run on the ground in minutes, with free provider-run test stations, moves that discovery to the hangar. The split between a basic self-service logon check and a scheduled, technician-assisted test mirrors how the work is actually divided: routine confirmation by the crew, deep diagnosis only when something has changed or broken.

The warning against KUSA illustrates a broader operational hazard. Test traffic sent to a live national authority is not a harmless mistake, which is why the providers publish dedicated test station IDs. The requirement to test separately on Link2000+ for EASA airspace also shows that a clean result on one network does not carry over to another.

The concrete next steps sit with each operator: checking the datalink procedure in their own AMM, and booking the 24-48 hour advance notice that Honeywell Forge, Collins Aerospace and Satcom Direct require for detailed testing.