Some details of a US carrier running one of the crash cause scenarios through its Airbus A330 flight simulators are being circulated on several private airline forums and on the public Pprune or Professional Pilots Rumour network.
It has been a long standing habit of airlines with a serious interest in flight standards to do flight simulations based on probable causes or using factual data as it comes to hand.
This is what happening in what is believed to have been a US flight simulator.
Dear Ladies and Gentlemen,
The scenario was conducted several times and the results at the end of each scenario produced consistent findings.
In an A330 simulator at FL 350 [35,000 feet] with a gross weight of 210 tonnes in ISA+10, with icing selected, the aircraft approaches a thunderstorm with a high intensity of turbulence. Due to the extreme turbulence, the autopilot disengages. Shortly thereafter a malfunction is selected to block both captain and first officer’s pitot tubes to replicate extreme ice formation.
The airplane reverts to alternate law with protection lost. There is a speed flag on both the captain and fo’s PFD [Primary Flight Display]. The severe turbulence activates repeated stall warnings. Manual thrust is being used at this time. The speed on the standby altimeter is reading 240kts or thereabouts with MACH 0.72. (From the GPS the ground speed is 350 kts or thereabouts. It is very difficult to read the instruments and ECAM warnings [fault and operational warnings].)
Updrafts take the aircraft up to FL 370 and produces a negative G of 0.2. The aircraft then enters severe downdrafts and the rate of descent averages more than 19,000 fpm [feet per minute]. The instinctive reaction is to pull on the stick to arrest the rate of descent. The aircraft shakes and buffets violently. The G force on the [pilot display] reads +5 but the instructor’s panel shows +8. The aircraft breaks up in flight around 20,000 ft.
After several attempts at this with all results being equal one could not see AF447 sending out any distress signals if this is what happened to them.
The email ends with a reference to any attempt to access the aircraft’s electronic manuals to trouble shoot the problems.
Applying an unreliable airspeed memory item would have proven to be very difficult because of the violent shaking and opening a QRH for an ADR check procedure even less likely.
This scenario is now being given considerably credibility in so far as it goes because the ACARS automated messages received by the Air France operations base in Paris indicate the pitots that measure airspeed failed at 0210 GMT on 1 June four minutes before the last message, an alert concerning vertical cabin speed, which derived from the air pressure value inside the jet.
It does not however explain why the jet was flown into such a violent storm cell when flights all around it were navigating through them without issues.
Air France also confirmed three days after the crash that the externally mounted pitots and static points manufactured by Thales had been found faulty in a serious of inflight incidents, leading the airline late in April to decide to replace all of them by the end of June.
However Air France has not explained why it initially blamed lightning as a possible factor in the disaster or claimed, incorrectly, that the ACARS messages recorded unprecedented electrical faults and short circuits.
The messages show no such thing, and give no support to what Air France said at the outset, while the lightning claim was nonsense. It is difficult to imagine that Air France did not know well before it conceded the flight was missing and officially feared lost that ACARS had identified autopilot disconnection and pitot or air speed data failures at the outset.