AF 447 Search to resume

[damirc]

Well here goes nothing. aa Been wondering for a long time if I should post here or not, but let's try it. As a warning - I have nil aviation background, I do deal with complex (computer) systems and their interactions.

Reading through the various documents available I'm still left very much puzzled as to the sequence of events. What is really puzzling is that from everything I've read I still feel AF447 was at least somewhat controllable (very low bank angle, relatively speaking normal pitch) until the very end, yet somehow they've ended up 30.000+ ft lower than at the start of the event sequence.

So a short analysis and a bit of speculation (please feel free to comment on the issues I have most probably gotten completely wrong).

0210Z - AF447 has been passing through an active cell, but has reached a zone of severe icing, and the pitot probes are starting to ice over (at varying speeds due to sightly different air flows). That far is clear. For this reason at 0211Z ADR2 is classified as faulty (fed by starboard side pitot probes), and the F/O presumably switched to ADR3 (the stby ADR), at 0212Z the remaining ADIRUs disagree and the NAV ADR DISAGREE message is sent via ACARS. AF447 is now without reliable air speed infication. Presumably we all agree thus far.

What they are left with is the GPS GS speed in the GPS monitor page. It is logical to presume that this (ADR2 failure) was the cause of the regression from normal law to alternate law (the 0210Z ATA: 279100 message), and the message at 0211Z explains the regression to ALTN law.

What is missing at this point is the regression to direct law - from everything I've read triple ADR failure causes a regression from alternate to direct law. I would have expected to see this message no later than 0213Z (but presumably even before NAV ADR DISAGREE).

Highly speculative part follows: Due to the fact that I cannot comprehend that an airplane with working engines and still fairly normally controllable (okay, with lost protections, but at least still somewhat controllable) flies into the ocean I speculate that the engines might not have been working at this time any longer.

Let me explain - I speculate that AF447 might have been caught in a massive updraft around 0214Z that pushed them considerably higher while at the same time causing compressor stalls in both engines (I presume the updraft would also cause massive airflow disruption into the engine).

At 0214Z the last ACARS message received was "CABIN VERTICAL SPEED". Can someone advise if this would necessarily mean a rapid descent or if it were possible that the static ports were also icing over (and due to simple physics when the "hole" is smaller the same amount of air moves faster through it and causes a reading of higher pressure (and as a consequence a lower altitude).

If the engines stopped working around 0214Z (from what I remember another ACARS message was supposed to be received no later than 0215Z), and I stress I might have gotten this totally incorrect, the RAT would have been deployed and the AC1, AC2, DC1 and DC2 busess would be left unpowered and only the DC ESS and AC ESS busses would be powered. Now if I read correctly then ACARS is powered by AC1, and once normal electrical power is lost, ACARS remains unpowered (which would explain the cessation of ACARS communications after 0214Z).

Also speculative is the assumption that they were unsuccessful in restarting the engines (reason uknown? potentially already in a deep stall at that point and simply running out of time) and might have attempted a ditching that did not succeed (but on a storm night with very low visibility and unreliable indications of at least speed, but probably also altitude and onto a water surface that was quite likely far from calm ... unfortunately they couldn't have done it). Again - this is highly speculative, I have nil aviation background, so be gentle in pointing out the mistakes in my thought process.

D.