Unless the passengers aboard were dead, they must have been aware that something was terribly amiss during those hours.
I believe it was a red eye type of thing. So if most of the passengers were asleep, and the the take over of the cock pit was quick and easy, nobody might have noticed an easy turn to the West.
Unless they were unconscious.
“Unless the passengers aboard were dead”
Seems like if the passengers were alive and there was a hijacking for 4 hours some of them would try to call on their cell phones. Would cell phones work over the ocean like that?