On Sep 12th, an Alaskan Airlines flight had a failure of their CMU (Comms Management Unit) that caused the Iridium connection to stop working. An ATC message was sent to the aircraft but not delivered. On the next flight, the CMU power was reset and corrected the issue, and the pending message was delivered. The CMU did not recognise the message as being old, and so it was presented to the Flight Crew as a control instruction. FSB understands that this aircraft took the climb instruction and executed the level change, climbing 1000 feet .
Another flight, operated by Hawaiian out of Oakland, had a similar problem. This aircraft had both Iridium and Inmarsat on board, and during the flight switched over to Inmarsat as the provider. An ATC message was routed via Iridium, but didn’t reach the aircraft before the switch. Some 23 hours later, on the next flight, Iridium was activated again and again the ATC message presented as a “live” instruction. On this occasion, the crew queried the instruction and did not climb.
add'l NOTAM locations (brief) more to follow
AUCKLAND NZZO B4985/17 - USE OF CPDLC (DATALINK) VIA IRIDIUM SATCOM
IS PROHIBITED WI NZZO FIR.
NEW YORK KZNY A0332/17 - FOR AIRCRAFT EQUIPPED WITH IRIDIUM SATCOM,
USE OF CPDLC IS PROHIBITED WITHIN NEW YORK CENTER OCEANIC AIRSPACE.