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Bea To Release Final Report On Af447

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French investigator to release final report into deadly 2009 Air France crash on July 5


PARIS (AP) - French investigators say the final report into the causes of the crash of Air France flight 447 will soon be published, three years after the jet went down in the mid-Atlantic killing all 228 people aboard.

France's accident investigation agency, or BEA, said in a statement Wednesday that the final report will be released at a news conference on July 5.

A preliminary report released last July highlighted a chaotic cockpit scenario before the crash, with a confused crew getting incoherent speed readings from faulty sensors, but it didn't draw a conclusion on whether pilot error, equipment failure or other unknown factors caused the crash.

The Airbus 330 passenger jet flying from Rio de Janeiro to Paris crashed on June 1, 2009

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I think most who have studied and "lived" this accident over the past three-and-a-bit-years know what happened but the engima is "Why?" I hope the HF group contributes broadly and that the report doesn't stop with the crew for if it does, the risk of a similar accident happening again, not necessarily a UAS event, remains. It is important to understand at least the possible/plausible reasons why a trained airline pilot would do this and why two other highly trained pilots did not intervene and did not assess the situation correctly. I don't think this is primarily an Airbus matter. Where they will likely be challenged is the ceasing of the stall warning (NCD - no computed data) below 60kts CAS even though the aircraft was in the air (but not "flying"), the THS (trimmable horizontal stabilizer continuing to trim the airplane while in Alternate Law, and the mess that is the Unreliable Airspeed Memory Items. I would disagree with the first two for technical reasons but have always considered, (from about June 4th, 2009 on) that the UAS drill was confusing to crews who had lost airspeed indications at cruise altitudes. The best thing to do when one loses all speed references is nothing, then get the books out.

The Air France Operational Safety Review done shortly after the accident but not related to it, (so they've said), nevertheless hold some observations of interest.

I hope the Report brings some closure to the families of the victims including the crew, but I fear it may not.


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AF447 inquiry grapples with stall-warning enigma


French investigators' attempts to unravel the reasons why Air France flight AF447's crew failed to recognise the Airbus A330's stall situation are seeking the possible inclusion of visual alarms to accompany aural warnings.

Seconds after pitot icing - and the loss of airspeed information - led the aircraft's autopilot to disconnect, the pilot gave a sudden nose-up input that caused the stall warning to trigger.

Investigation agency BEA says analysis of 17 events occurring in similar conditions to those affecting AF447 illustrated that crews found the stall warning "surprising" and "frequently mentioned their doubts" over its relevance.

"These judgements may be explained by the lack of awareness of the margins in relation to the trigger threshold of the stall warning and by not knowing the triggering conditions of the warning," the BEA says.

Although AF447's non-flying pilot may have noticed the brief warning, it adds, he might not have been able to put it in context - possibly because he was unaware of the flying pilot's nose-up response, the relative proximity of the limits of the flight envelope, and the switch to alternate control law which removed angle-of-attack protections.

More mystifying was the apparent failure to react to the prolonged second stall warning, lasting for 54s, generated as the aircraft climbed out of its assigned 35,000ft (10,600m) cruise level towards 38,000ft.

But in the 46s between autopilot disconnection and this second stall warning, another alert - the "C-chord" altitude horn - had sounded almost continuously for 34s.

"In an aural environment that was already saturated by the C-chord warning, the possibility that the crew did not identify the stall warning cannot be ruled out," the BEA states.

It cites cognitive research suggesting that visual, rather than auditory, information is prioritised by pilots coping with high workloads.

"Piloting, calling heavily on visual activity, could lead pilots to a type of auditory insensitivity to the appearance of aural warnings that are rare and in contradiction with cockpit information," the analysis says.

Although some of the flying pilot's actions appear consistent with approach-to-stall procedures, the BEA cites evidence that the pilot might have interpreted certain cues - such as buffeting and aerodynamic noise - as an indication of overspeed rather than stall.

Not only had the pilot reduced thrust shortly before the prolonged stall warning, but he also later mentioned having an "impression" of speed, and there was an attempt to extend the speedbrakes.

The BEA also states that the flight director was advising a nose-up attitude, and this "may have confirmed the [pilot's] belief that the stall warning was not relevant".

"In its current form, recognising the stall warning, even associated with buffet, supposes that the crew accords a minimum level of 'legitimacy' to it," it notes.

The BEA also says the pilot might not have been fully aware of the A330's switch to alternate law, and perhaps "embraced the common belief" that the aircraft could not stall.

While the master warning indicator light would have supported the aural alert in signalling the onset of the stall, the BEA is recommending that the European Aviation Safety Agency determines the conditions in which a dedicated visual indication should be made mandatory.

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