Hello,
Last July, I've made the assumption, based on body recoveries that the actual plane crash might have been South of last known position (0210), and that the search was not primarily conducted at the right place (mostly because wreck was not located).
In fact, the primary searches were focused on the "upset theory": loss of control followed by crash very closely following the last ACAR sent.
But another possibility existed: that the end of ACARs was not due to aircraft crashing but to loss of NAVSAT. Consequently, this aircraft could have crashed somewhere and sometime after this last ACAR was transmited. Nothing in those ACARS was telling us that this aircraft was in total perdition at 0214. It might have continued for some time on its flightplan, then turned back due to bigger failure than probe icing, but of course, one causing NAVSAT failure. This also ruled out a critical airframe damage as this aircraft should have been able to fly much longer in this case. The main difficulty in order to verify this hypothesis was addressing body drift which seems to be quite difficult in this area.
So far, everything is confirming this hypothesis. The airframe was possibly intact at impact time; the bodies drifted North-East, and if the wreckage is to be confirmed at this spot, it means that it turned back and was very possibly still under crew control after 0214 for quite some time:
- we still don't know at what point decision was made to flight back.
- we still don't know what could have caused NAVSAT failure, but we have a suspect called ICE.
It is now more and more improbable that any decision to turn back could have been made before this last ACAR was actually transmitted: because of probe icing, the following system failures, and due to flight conditions into this thunderstorm zone. This could have ruled out any change of direction until something much more critical happened. By 0214, this aircraft was almost out of the thunderstom zone, it seems hard to decide to come back on it or to attempt any maneuver being surrounded by high conv cells.
NAVSAT failure is either NAVSAT related, then certainly non critical for flight safety, either, it is power related. Ice (the only one proved suspect so far) doesn't make power supply to stop until both engines are shut down. As a matter of fact, Ice may really cause dual engine flameout. See here:
Engine icing & flameout at 38,000 feet/cruise (PIC)
No more ACAR recieved would imply that they would have been simultaneously shut down.
It would be nice to know from an experienced pilot, what he would do in such a case:
- severe icing observed, loss of speed indication and systems, alternate law2, while being in the middle of a thunderstorm zone (supposed cleared by deviation but aircraft surrounded by it).
- event lasting more than 4-5 minutes of flight, then dual engine flameout.
- what will he do next ?
Last, question about FDRs:
- If power was lost, what happened to FDRs records? are they stopped also in this aircraft?
If so, and even if the FDRs are retrieved, recorded data between 0210 and 0215 would be difficult to figure out due to probe icing, and nothing more to expect after this point.... same for voice recorders.
S~
Olivier