Where?
Takata,
Aaaaah yes, there are so many Unknowns! So many IFs. So many Possibilities. So many Questions.
My bad, not to clarify "BEA have not searched there yet" by adding "with side-scanning sonar." Appendix 2 of the 2nd Report includes a graphic ("Lanes defined in the search zone") and states "The SAR was operated on line 24, squares J,K, L and M." That's eight to ten nautical miles southwest of the Last Known Position, so it seems that IFREMER’s Towed Acoustic Sonar (TAS), with its 1 pixel for 25 cm resolution, only explored a tiny corner of the area within a 10nm radius of the LKP during Phase 2.
It's unfortunate that the very best assets (including a nuclear submarine) and TPL technology could not locate the pingers during Phase 1 in the Alpha Zone or elsewhere before their predicted battery life expired. As you say, if the wreckage is really in a tight circle near the LKP, both pingers could have been destroyed during the crash. Recommendations are already in place for lowered beacon frequencies, and pinger specs and CDR methodologies are undergoing a broad re-evaluation by the industry.
The timing of events with clues only in the ACARS messages is very tricky. My thinking is that for the 02:14:26 cabin vertical speed message to be sent, it had to be triggered by a rapid descent at least a minute or two PRIOR to its transmission. As the BBC experiment showed, a fall of 19,000 feet in 50 seconds might be a worst-case possibility. So the actual falling event must have begun well before that last message was timestamped and sent. In any case, it would seem that loss of control (the upset) occurred closer to 02:10, well before the cabin vertical speed message was sent. The idea of straight-and-level cruise flight much beyond AP Disconnect at 02:10:10 is difficult for me, but I am continually trying to simplify a very complicated event.
Aaaaaah, the unknowns.
Without doubt, the BEA search effort has gathered the best minds and resources to recover the hull and black boxes. It's simply one of the most difficult researches so far undertaken in this 21st Century.
Thank you for your considered feedback.
GB