Dani;
Originally Posted by Dani, post 2868
It's very unlikely that they ditched. It's very unlikely that they glided towards the water for any reason.
Correct. That's exactly what the BEA is trying to convey: level aircraft attitude, vertical trajectory with possible slight forward and perhaps even aft, trajectory, (possible explanation of the condition of the one spoiler found - torn out by reversed airflow, as someone posited a thousand posts ago) - not a straight line down, in other words.
The following are some considerations of other system faults which would likely have developed in any such stalled condition. There is no evidence for these assumptions but they are reasonable, given the vertical descent scenario described by the BEA.
We don't have evidence but may surmise that with such high angles of attack, the engines would have flamed out, (for those not familiar with this and would question this, flameout would be due to the extreme angle between the engine intake cowling and the air passing "upwards" almost at right angles to the axis of the engine. As such, air would not enter the engine in a smooth path).
Therefore, (again an assumption based upon the BEA's scenario), once the stall was fully developed and as engines flamed out, electricity and hydraulics would be lost except for what was available from the two batteries. The APU which has it's own battery could nevertheless not be started both given the time available and the highly disturbed airflow which would obtain in the BEA scenario, (again, roughly perpendicular to the axis of the aircraft).
Under such circumstances (loss of electrical generation on both AC buses), the RAT would deploy but would not supply emergency hydraulic pressure for flight controls or the emergency generator due to the direction of the airflow.
Providing the DC Essential bus was powered by the batteries, the cabin pressure controller would be powered. I can't find in the AMM what powers the outflow valves themselves but one could assume it would be from either the AC or DC essential buses. Perhaps someone can determine this.
With a flameout, airflow from the engines to the two packs would be lost and the cabin altitude would, after some time had passed, slowly begin to climb.
Please NOTE: I doubt very much whether the "Cabin Vertical Speed" ACARS message was generated as a result of engine flameout and consequent loss of airflow to the cabin. Flameout would be an event which would have occurred much later in the accident sequence after the stall was fully developed,
again as envisioned by the BEA. (to lay the logic of this out fully...loss of both engines does not cause an immediate loss of pressurization, nor does it even result in a high cabin rate of climb. By the time any significant cabin rate of climb obtained, the capability of sending ACARS messages would have long been lost).
NOTE: These are some considerations of other system faults which would likely have developed in any such stalled condition. There is no evidence for these assumptions but they are reasonable, given the vertical descent scenario described by the BEA.