Unlikely scenarios...
Quote from takata (post #3093):
a) How long did they maintain cruise altitude?
It is still unknow without the recorders. It seems that they may have lost a lot of altitude at the end of the sequence (02.14) when the pressurization valve opened. An emergency descent up to 8,000 ft/mn is plausible or it may be due to a previous but recovered upset.
b) a gently stalled aircraft from cruise level would take about 10-15 minutes to reach sea level, not 5 minutes, and it would certainly cover a fair distance from LKP if not circling around.
c) At impact time, this aircraft seems to be in controled fligth attitude... if powered. This may be due to a failed attempt to relight its engines without having enough altitude in order to come out of the dive to build up speed: a CFIT at the dive bottom rather than an upset from cruise lasting up to this point.
d) an attempt to ditch seems very unlikely.
Salut, I think you were giving consideration to less-likely scenarios, even though you agree with me that flight beyond about 0215z is unlikely?
So I will try to join your discussion, further to my earlier comments:
"If they had maintained cruise altitude during that 4 -5 minute series of failures, and then had a simultaneous double-engine (and therefore double-generator) failure, they could indeed have glided for about 12 -15 minutes. Seems a bit odd that they should end up ditching without pre-warning cabin crew and passengers, and find themselves within about 15nm of where they were when their problems began."
Just to remind others, the absence of any received ACARS messages after 02:14:26 (at least one was due) is most likely explained by complete loss of AC generator power. Now: back to your above-quoted points.
In (a), you recognize that the most likely explanation for the Cabin VS warning at 0214z is that the aircraft was descending rapidly through about 6000ft, with the inward relief valve opening because the cabin altitude was >6000ft. However, a simultaneous double-engine failure at cruise altitude could produce the same warning until the outflow valve had a chance to close to maintain cabin pressure.
In (b), a "gently stalled aircraft" for over 10 minutes from cruise to sea-level seems a big stretch of the imagination. As you say, it would also involve a circle or tear-drop to get back close to the LKP.
In (c): with the high probability of a double-engine failure leading to a ditching, the flight crew would know that the cabin crew must prepare the passengers accordingly. The fact that this was not done suggests there was insufficient time, and/or the cabin crew were unable to reach either their interphones or the cockpit, due to an upset.
In (d): if the PF had regained control, but neither engine was running, he would be doing his utmost to achieve a controlled ditching. But we know that the vertical speed was still enormous. The PF may or may not have been recovering from an even higher VS.
I still go for loss of control between 0210z and 0211z, possibly as they exited the Cb.
KTVaughan, Didn't Tim Vasquez mark the LKP on his graphics?
Chris (with apologies to Bobman84...)