Does a double engine ice event and subsequent controlled descent actually fit all the ACAS signals without further complexity.?
Does an engine flameout from icing make an ACARS message of any type? If so, is it a failure or a warning message? Is there a cockpit flag or indicator if an engine flames out? If so, it might make an ACARS warning message.
We know that ACARS can't send after both engines are down. But it appears that it should be able to send if only one engine is down.
If an engine down creates a failure message (and only a failure message), and both engines go down within less than 60 seconds of each other, then we would not see the failure because failures are held for 60 seconds, and the AC1 bus might have gone down before the close of the window.
On the other hand, if an engine down causes a warning message, or causes a cockpit flag or indicator that would be reported with a warning message, then since warning messages are sent 'immediately' (within a few seconds, normally) then I'd expect to see something about one or both engines going down before power to the ACARS data chain was lost.