Air France 447; some tough questions

Posted on 10. Jun, 2009 by in Featured

“Without key information from the Airbus A330’s missing data recorders, investigators have focused on the possibility that external speed monitors — Pitot tubes — iced over and gave false readings to the plane’s computers as it flew into thunderstorms.”

Why then, after the first 6 flight control events did the European Aviation Safety Agency (EASA) issue two Emergency Airworthiness Directives (EAD) involving the ADIRU in December and January? These mandatory Directives dealt with the ADIRU #1 and the inability to shut it down as it gave faulty information overriding the remaining two ADIRUs.

This faulty data caused a violent pitch event in the case of QANTAS Flight 72. After two incidents involving QANTAS flights the Australian Transportation Safety Board asked Airbus for technical data for any similar events. After initially being told there was none Airbus later found there were 4 previous events in data files simular.

Why wasn’t an EAD issued for the pitot systems to be replaced?

What has changed the engineer’s determination that the cause of previous events was the inability to get a faulty ADIRU out of the loop to the sensor (pitot)? We must keep in mind that in the previous events the aircraft were not lost, all information was available including the flight data recorders (black boxes). And yet the EADs were issued for the ADIRU not the pitot system.

Loss of airspeed in and of itself will not bring down an aircraft due to structural failure. Rule number one in aviation; power plus attitude equals performance. When you are learning to fly they drum that into your head and again if you go into flight test. “When all else fails, remember power plus attitude equals performance.”

I’ve lost all reference to airspeed and angle of attack twice in my career. Once in a TA-4J and once in a Cessna 172, both cases were a non event. Set an average power setting to maintain speed at altitude, idle or decent power to descend. By maintaining a heart of the envelope attitude the airspeed will remain well within the performance envelope of the aircraft.

Loosing airspeed indication certainly should not make the tail separate from the aircraft, there has to have been an excessive side load or some sort of catastrophic event. A close up of the tail shows no significant damage to the leading edge of the vertical stabilizer (see below). Thus it is very improbable it impacted the ocean at a significant speed (with the fuselage).


An over speed with resulting instability and side loads could have been the cause, however in light of the information stated and previous EADs issued by the EASA I think it unlikely.

No Responses to “Air France 447; some tough questions”

  1. Rick 10 June 2009 at 11:00 #

    Woudn’t our own FAA have the ability/jurisdiction to issue an EAD on the pitots? I’m not sure I understand why we’re deferring to the europeans.

  2. Chip 10 June 2009 at 11:27 #

    France has the lead in the investigation. Although the NTSB and FAA are involved in an advisory capacity according to some press I’ve seen. I suspect this will get very sticky!

  3. Rick 10 June 2009 at 15:29 #

    Yes I do know France has and should have lead for this investigation. But the FAA has knowledge of this defect and I’m wondering why they aren’t out with an EAD on US flagged carriers….seems like a no-brainer to me. I’m presuming the airlines are probably self-policing and are doing it anyway, but I haven’t seen any press to that point.

  4. Chip 10 June 2009 at 15:44 #

    Good question; I do not know.

  5. Rick 10 June 2009 at 17:24 #

    Interesting afticle here. Anything’s possible, I suppose. Still, I think it’s probably unconnected.

  6. Chip 10 June 2009 at 17:37 #

    I read it on my union website. IMO it is noise, don’t know how they would get all the codes etc to be sent automatically by ACARS. Voice recorder will verify it. I see it only took the French Navy 10 days to get a nuclear sub on station.

  7. Rick 11 June 2009 at 09:04 #

    Another interesting article this morning.

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