ORAC, Am I correct in thinking that you believe it is possible that it was not tracked, - or rather, it is possible that it would not have raised any military interest?
I'm saying it was practically certain it was originally detected, tracked, and identified as friendly as an outbound track. The track block would have given the track ID and, only perhaps, the height. When the SSR was turned off it might not even have been noticed. (I had occasions when I was controlling myself when someone had to point out my aircraft wasn't squawking).
As a friendly it would not of been a high priority, they would have been watching other unknown tracks and trying to identify them.
The question then arises as to whether the turn back would have raised an alert. Unless it was a sophisticated system with flight plan tracks being continuously monitored for adherence (which I am almost certain was
not the case,) then the system would not have generated an alert unless it squawked radio fail, hijack or radio fail. Would the operator have seen it as suspicious? Bored airman keeping tracks on blips, unlikely.
The remaining possibility would have been if ATC called to say they'd lost contact, but they'd sent him over to HCM control and thought he'd gone. HCM didn't query his non-arrival on frequency (lack of comms between ATC centres?) so that didn't happen either.
When the track went overland/primary went below cover the track would have automatically timed out and been dropped and it would not have been seen as of interest.
When a non-squawking
outbound track appeared off the west coast it would either have been made friendly or unknown based on track behaviour (coming from friendly territory) and again dropped when it left radar cover.
In short, the whole turn and transit until it left cover is highly unlikely to have raised an eyebrow until questions were asked and the tapes pulled. At which point embarassed execs would have started waffling rather than admitting that's how the system works.