What Happened to Air France 447?

Similar Air-Data Anomalies Reported

Air Transport World (ATW Daily News Monday June 29, 2009) reported that the U.S. NTSB is investigating two incidents, one on May 21st and the other on June 23, 2009, during which airspeed and altitude information aboard Airbus A330 aircraft may have malfunctioned. The incident in June was described as, “The aircraft entered the cloud tops and experienced light to moderate turbulence. After about 15 sec. it encountered moderate rain that was visible on the windshield. The pilots noted that the cockpit suddenly became very warm and humid and a few seconds later all three airspeed indicators rolled back to 60 kt. and autopilots and autothrottles disengaged, as did rudder limit protection …” In both of these incidents, the aircraft continued to a safe landing.

August 2009 Update: Europe Proposes Airworthiness Directive

On August 10, 2009, the European Aviation Safety Agency (EASA) issued notice of its proposal for an airworthiness directive, stating, “Occurrences have been reported on A330/340 family aeroplanes of airspeed indication discrepancies while flying at high altitudes in inclement weather conditions”. If adopted, the airworthiness directive would require replacement of the Thales pitot tubes currently installed on the A330/340 fleet with another Thales pitot tube, which is believed to improve airspeed indication in heavy rain conditions. The full text of the proposal is here: easa_pad_09-099_1.

Then, on August 31, 2009, EASA issued AD No. 2009-0195, summarized as follows:

Occurrences have been reported on A330/340 family aeroplanes of airspeed
indication discrepancies while flying at high altitudes in inclement weather
conditions. Investigation results indicate that A330/A340 aeroplanes equipped
with Thales Avionics pitot probes appear to have a greater susceptibility to
adverse environmental conditions than aeroplanes equipped with Goodrich
pitot probes.
“A new Thales Pitot probe P/N C16195BA has been designed which improves
A320 aeroplane airspeed indication behaviour in heavy rain conditions. This
same pitot probe standard has been made available as optional installation on
A330/A340 aeroplanes, and although this has shown an improvement over the
previous P/N C16195AA standard, it has not yet demonstrated the same level
of robustness to withstand high-altitude ice crystals as the Goodrich P/N
0851HL probe. At this time, no other pitot probes are approved for installation
on the A330/A340 family of aeroplanes.
“Airspeed discrepancies may lead in particular to disconnection of the autopilot-
and/or auto-thrust functions, and reversion to Flight Control Alternate law.
Depending on the prevailing aeroplane altitude and weather environment,
this condition could result in increased difficulty for the crew to control the
aeroplane.”

The full text of the European AD requiring replacement of the A330 pitot tubes with either an improved Thales part number, or Goodrich pitiot tubes, can be found here.

Underwater Search for Wreckage

Clues to help determine the cause of the crash are being sought by ships and submersibles in the mid-Atlantic. The New York Times on June 19, 2009 published an illustration depicting the sea floor and describing the search. The two most sought-after items: The flight data and cockpit voice recorders.

Status of Investigation: August 2009

As of July 7, 2009, the flight data recorder and cockpit voice recorder have not been located. Because the ‘pinging device’ is only expected to last 30 days, and that time has expired without the recorders being found, it is likely that they will never be recovered. There are no witnesses, either from aboard or outside the aircraft. The accident reminds us of a bygone era, when an aircraft departed and later was  simply declared overdue and presumed lost. Were it not for the routine maintenance data automatically uploaded by the aircraft, we would have even fewer clues to the loss. Thankfully we have weather data from the mid-Atlantic Ocean, to correlate with the information uploaded by the aircraft. Our prayers for those lost and condolences to their families and loved ones.

About the Author

Dave Alden is a line pilot for a U.S. Part 121 airline, and an attorney who practices aviation law from offices in Sacramento, CA.

Further Updates

Since this article was written in the months immediately following the accident, additional evidence has been recovered and findings made. Further, the U.S. FAA updated Airworthiness Directive 2004-03-33, pertaining to Thales pitot tubes in 2009.  See Air France 447 Recorders Found for more.


Aviation’s Ironies

Johanna Ganthaler, an Italian woman vacationing in Brazil, missed AF447 but caught another flight the following day. She was killed in an automobile accident driving home from the airport, when her car swerved into an oncoming truck in Kufstein, Austria.

Five passengers decided to miss BOAC 911 on March 5, 1966, which crashed with the loss of all aboard. Cubby Broccoli, Harry Saltzman, Ken Adam, Lewis Gilbert and Freddie Young were in Japan scouting locations for the James Bond film, You Only Live Twice. Source: Wikipedia, BOAC 911. Note the final irony: That prophetic flight number.

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