ARINCDirect's Most Frequently Asked Questions - U.S. Domestic CPDLC

Welcome back to Jump Seat. Today we’ve turned our platform over to our ARINCDirect FANS (ADFANS) trainer, Jen Johnson, to share her most frequently asked questions regarding the United States Domestic Datacomm Program.  

Q: Where can I find the latest information and updates on the US Domestic Datacomm program? 

A: I highly recommend reading the L3Harris monthly Data Comm Program Operators Newsletter, which can be found under “U.S. Domestic En Route CPDLC Guides” on the L3Harris FAA Data Comm User Information website. This newsletter usually updates the first week of each month.  

Q: Where can I find a flight planning filing guide for US Domestic CPDLC? 

A: L3Harris' U.S. Domestic CPDLC Flight and Route Planning Guide can be found on the FAA DataComm website under  “U.S. Domestic En Route CPDLC Guides”. Be sure to check out Appendix C (pages 16-17) for a full list of Field 18 DAT/ codes.   

Q: What are some common reasons that US Domestic CPDLC might fail? 

A: Some common reasons that a KUSA logon might not be successful include:   

• Flight plan is not filed or has timed out. There must be a flight plan on file with ATC to successfully log on to KUSA.  
• Incorrect Filing Codes. Ensure you have the following filed correctly in your flight plan: 
• J-Codes (J4 is required for US Domestic En Route CPDLC) 
• REG/ in Field 18  
• CODE/ in Field 18 that correlates with the registration in the REG/ entry (if these do not match, the CPDLC session will be terminated) 
• DAT/ in Field 18 (only file the En Route codes if registered with L3Harris) 
• Aircraft NOT registered with L3Harris. 
• US Domestic En Route CPDLC requires the aircraft to be registered with L3Harris. See the FAA DataComm website for registration details.  
• Please note that FANS Departure clearances (FANS DCLs) do not require registration.  
• Incorrect Flight ID on the Logon/Status page 
• The Flight ID entry on the FANS Logon/Status page must exactly match Field 7 of the filed ATC flight plan. 
• Aircraft is NOT transmitting via VDL Mode 2 
• VDL Mode 2 is the preferred media for participation in US En Route CPDLC. 
• Ensure that the COM3/VHF3 (or alternate verified radio) is set to DATA, not VOICE. 
• Note: ATC uplinks to the aircraft over SATCOM or HF will not be delivered to the aircraft; four consecutive failed uplink messages will result in the termination of the current CPDLC session. Click here for more details. 

Q: Can I use US domestic datalink while PIA is in use? 

A: Yes! And as of December 2024, when filing a flight plan using ARINCDirect, you can file as usual – no extra information is required on the filing screen.   

Remember: Every PIA flight plan is assigned with a unique Rockfish callsign (ex. XAA1234) that is filed in Field 7 of the ATC flight plan. The Flight ID on the FANS Logon/Status screen must exactly match Field 7 of the filed ATC flight plan to successfully logon to KUSA. Since your callsign changes with every PIA flight plan filed in ARINCDirect, this means your Flight ID for logging in to KUSA will change with every flight, too!  

Q: Where can I find information on Full Services CPDLC messages?  

A: “Full Services” messaging, which adds new route, holding, weather deviation clearances, and free text advisory uplinks, are currently enabled in the following ARTCCs: Denver, Albuquerque, Fort Worth, Houston, Memphis, and Minneapolis.  

• Full Services functionality is discussed in-depth in the Pilot Handbook – U.S. Domestic En Route Controller Pilot Datalink Communication, available on the FAA DataComm website under “U.S. Domestic En Route CPDLC Guides” (latest version published on 9/25/25). See chapters 8 & 10 of the pilot handbook for full explanations of these new Full Services Messages. 
• The Data Comm Program Operators Newsletter on the L3Harris FAA Data Comm User Information website also contains information on Full Services Messages. 

Q: Can you provide an update on Eastbound Oceanic Clearance issues?  

A: In January, the FAA released InFO 26005 which addressed the failure of crews to promptly/correctly load CPDLC Route Uplinks. As a result, Gander ACC has reported increased frequency congestion, pilot errors, and ATC workload. The InFO highlights two specific issues:  

• CONFIRM ASSIGNED ROUTE.  

Gander ACC standard practice is to:  

1. Send a route uplink to the aircraft 
2. Receive the WILCO 
3. Wait about five minutes, then send the CONFIRM ASSIGNED ROUTE message to the aircraft.  

Gander ACC reports that flight crews have been responding to the CONFIRM ASSIGNED ROUTE message before loading the full new route, leading to ATC out-of-conformance alerts. Ensure that the full new route is loaded prior to responding to the CONFIRM ASSIGNED ROUTE message. 

• uM79/uM80 uplink messages.   
• The uM79, “CLEARED TO [point] VIA [route clearance]”, is not a clearance to proceed direct to the [point] displayed in the uplink, but rather a new route to that [point].  
• The uM80, “CLEARED [route clearance]”, is not a “cleared as filed” message. It is a new route.  

Note: You can find detailed information on both the uM79 and uM80 the Pilot Handbook – U.S. Domestic En Route CPDLC (find the latest version under U.S. Domestic En Route CPDLC Guides), currently located in Chapter 8.  

Did You Know?

• As an added benefit, ARINCDirect datalink subscribers have access to our FANS Automated Test Stations. This quick test allows customers to test the functionality of CPDLC and ADS-C anytime, anywhere, while connected to the ARINCDirect network. For more information on ARINCDirect FANS automated quick testing, please contact ADFANS@collins.com.
• Need to manage and adjust your aircraft equipment codes? ARINCDirect account admins can access the Tails section under the My Company tab on the ARINCDirect website. Select your tail, make your changes, and be sure to click Save. Need assistance? Contact the 24/7 ARINCDirect Flight Operations team at ad-flightops@collins.com.

Useful Links

• In an upcoming issue of Jump Seat we will cover ARINCDirect’s most frequently asked questions regarding ATN CPDLC in Europe. In the meantime, Eurocontrol has put out a new resource guide for CPDLC in Europe for 2026, find it here.
• Avionics Customer Portal