Thursday, July 5, 2012

Air France 447: Equipment Problems; Stall Warnings; Pilot Error

Air France Flight 447 took off from Rio de Janeiro and headed toward Paris. Some time later, the Airbus A330-200 disappeared from radar.

Evidence, But Not Much

That was May 31, 2009. By June 10, we knew that an airliner and 228 people had disappeared, and that:
  • Two names that were on a terrorist watch list appeared on Air France Flight 447's passenger list
  • The Airbus A330-200 had an older set of Pitot tubes
    • Air speed sensors
  • Pilots in the area saw an "intense flash" when the airliner disappeared
  • A fuel slick found wasn't jet fuel
    (June 10, 2009)
All we knew was that more than 200 people were missing and presumed dead.

I could make that bright flash seem like an explosion, but there was a thunderstorm in the area: and lightning is notoriously bright.

Passengers with names that appeared on a terrorist watch list were suggestive, but far from proof. The names may not have been as common as "Jim Johnson" was in northern Minnesota: but different people often have the same name.

The Pitot tubes, which were going to be replaced, hinted at technical problems: but a 'hint' isn't proof.

Almost two years later, AF 447's flight recorder was found. (April 28, 2011

Training Pilots: Yes, It's Important

Apparently AF447's pilots hadn't been trained for high-altitude flight, or what to do when airspeed sensors don't work right. (BBC News, July 29, 2011) Putting them on a high-altitude flight in an airliner with slightly obsolete airspeed sensors may not have been a prudent decision. Air France says that the pilots were so trained.

Airbus and Air France may face manslaughter charges over the little oopsies in AF 447.

A BBC News article included a timeline of the last few minutes of Air France 447:
"...0135 GMT: The crew informs the controller of the flight's location

"0159-0206 GMT: The co-pilot warns of turbulence ahead before the captain leaves the cockpit for a rest break

"0208 GMT: The plane turns left, diverting from the planned route. Turbulence increases

"0210 GMT: The auto-pilot and auto-thrust mechanisms disengage. The plane rolls to the right. The co-pilot attempts to raise the nose. The stall warning sounds twice and the plane's speed drops. The co-pilot calls the captain

"0210 GMT: The stall warning sounds again. The plane climbs to 38,000ft

"0211-0213 GMT: The captain re-enters the cockpit. The plane is flying at 35,000 ft but is descending 10,000 ft per minute. The co-pilot says 'I don't have any more indications', pulls the nose down and the stall warning sounds again...

"...02:14 GMT: Recordings stop"
(BBC News)
I think there are a few things to learn from AF 447, including:
  • 'Accidents happen'
  • It's a good idea to train pilots
  • Faulty equipment isn't reliable
  • Deferring judgment until there's enough evidence is sensible
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Wednesday, July 4, 2012

Independence Day, 2012



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