One can hope.. at least in the case of UA 93 there were phone calls by multiple passengers and crew that were transmitted and verified of hijacking, situation on board, their intentions of takeover etc.
In the case of MH 370 there is nothing of that sort. As far as I know there were ZERO communication of that sort from either passengers or crew to the ground in terms of flight change, environmental conditions etc.. ZERO.
Heck no even a simple 'Hi I'm going to China' etc etc to any love ones.
The plane gone 100% dark after passing the last verifiable waypoint.
Well...it was basically a red-eye flight. Took off at 00:42 from Malaysia so I imagine that very quickly most passengers were sleeping or sitting quietly. By the time the aircraft was out to sea, there would not have really been anything to see out the window (and really would not have been once they took off and got away form land).
The final voice contact from the Captain occurred at 01:19, 37 minutes into the flight after he had reached and was cruising at the 35,000 ft cruise altitude.
Sometime before 02:03 the official satellite communication link is turned off or otherwise lost (this is NOT the hourly handshake, which continued on)..
By 02:18, Malaysia Airlines Operations Center indicated that it had signals from MH370 indicating it was in Cambodian airspace...where it is not supposed to be. So by that time, the course had certainly changed. But this is now 1 hour and 36 minutes into the flight...very early in the morning and the flight, over the sea, is probably not somewhere where passengers would be unduly alarmed or even wondering.
I believe by that time, whatever untoward thing that happened to the aircraft (ie. hijacking and changing course) had already happened.
Were the rest of the crew or any of the passengers aware of it? We just do not know.
Were they incapacitated somehow? Pure speculation. We just do not know.
At 02:22 the last primary radar contact with the aircraft (from the Malaysian military) was lost.
After this point, outside of the hourly handshakes that were later talked about and used to try and triangulate where the aircraft was, there was no further indication from MH370.
At 02:39 a ground to aircraft telephone call is attempted to the aircraft...but it goes unanswered.
At 06:30, the aircraft missed its landing in Beijing.
At 07:24, Malaysia Airlines officially announced the aircraft as missing.
At 08:11 the aircraft had its last full satellite handshake.
At 08:19 the aircraft sent a "log on request" to the satellite, but no handshake occurred.
Some investigators think this last thing happened as the plane ran out of fuel, before emergency generators kicked, and as the plane descended towards wherever it crashed...a kind of final act by the electronics on the aircraft to establish a link.
Short of some really sharp or violent turns through this, while it was still dark, there would have been no real reason for passengers to suspect anything untoward at least up until the time they should have entered Chinese airspace before descending to Beijing.
I suspect, that by the time anyone may have figured out something was wrong, they were well out of range of cell phone operation anyway...if they were still conscience. If someone had a sat phone...maybe they could have gotten something off. But not many people have those.
It is sure enough a bonafied mystery.
I am glad they found the wreckage to give the families at least that level of closure for sure...but short of finding real evidence about what actually happened out there...they will be wondering what really happened to their loved ones for the rest of their life..