but it wasn't an unidentified track. It was an identified Friendly track which turned round - and if the operator didn't know it's flight plan why would he assume it wasn't planned to?
ORAC - Yes, I accept that as far as it goes, but doesn't the "friendly " assumption cease to be valid (or least shouldnt a seed of doubt be sown) at the point that the IFF is switched off and and voice transmissions cease. I'm assuming some liaison between civilian and military ATC here, maybe that's a rash assumption.
And dont forget that up to the point they were highjacked, all four aircraft involved in the events of 9/11 were "friendly".
PS Latest nonsense all over the news tonight - it has been established the the co-pilot/first officer made the final transmission. Shock horror, aircraft captain delegates routine transmissions to the RHS - that's never happened before!