14-2-3

System Situations

JO 7110.65BB, Change 3, effective July 9, 2026 · Official text on faa.gov

If the CPDLC system fails to provide a necessary automated altimeter setting to an aircraft, the controller must issue an altimeter setting in accordance with FAA Order JO 7110.65, Chapter 2, Section 7, Altimeter Settings.
Note

If the CPDLC system fails to provide an automated altimeter setting, the controller with eligibility will be notified with an abnormal indication in the FDB. Automated altimeters are only sent in response to a monitor transfer of communication (TOC), or an altitude uplink when the assigned altitude is below FL 180.
When a CPDLC connection is unexpectedly lost with an aircraft, and voice communication had not previously been established, the controller must ensure voice communication is established and maintained with that aircraft.
Whenever there is a shutdown or failure of CPDLC service:
1. Controllers must use voice to broadcast a message alerting pilots to the shutdown and request no pilot downlinks until further advised.
  Example
  
  “Attention all aircraft; CPDLC no longer in use. Do not downlink any messages until further advised.”
2. Controllers must take action to ensure that any open or abnormally closed uplinks at the time of the shutdown are resolved, by voice, with each aircraft.