Investigators call airplanes' speed monitors into question
Latest update : 2009-12-17
The French aviation accident investigative body, the BEA, has said the causes of mysterious Air France 447 June crash remained unclear, but called for new testing standards for air speed monitoring on aircrafts.
AFP - The inquiry into the loss of an Air France jet that crashed into the Atlantic with 228 people on board called Thursday for new testing standards for air speed probes, which it said ice up at high altitude.
In an interim report on the June 1 crash of flight AF447 from Rio to Paris, the French air accident investigation agency BEA said that, while it has yet to confirm the cause of the accident, the plane's Pitot probes were faulty.
The BEA agency's report said that Airbus, which built the missing A330 jet, had identified 32 cases between November 12, 2003 and the date of the crash in which two or more of these air speed monitors had iced up on its planes.
When Pitots are blocked by ice they send false speed measurements to the plane's onboard flight computers, as was the case on the missing flight, which sent a string of automated error messages before plunging into the ocean.
The BEA, which has already ordered airlines to replace the European-designed Pitots on their A330 and A340 Airbus jets with a US-made model, called in its latest report for new testing standards for the device.
"In practice, the testing criteria are not representative of the conditions really encountered at high altitude, in the case of temperatures for example," the investigators wrote.
"What is more, it seems that certain points -- for example the size of ice crystals inside cloud masses -- are not well understood and it is therefore difficult to evaluate the effects that could have on Pitot probes."
Pilots' unions and some of the relatives of victims of June's crash have accused Air France and Airbus of ignoring longstanding problems with air speed monitors on its jets in the run up to the June disaster.
The companies insist that their jets met all safety standards, but they have nevertheless now replaced the Pitots with a different model.
The BEA has said that the missing jet was receiving false speed data from its Pitots, as it flew at high altitude through a tropical zone known for dense cloud formations, but has not confirmed the cause of the crash.
Crash investigators have not been able to recover the AF447's black box flight data recorders from the ocean off Brazil, and the inquiry into the accident is continuing.
In an interim report on the June 1 crash of flight AF447 from Rio to Paris, the French air accident investigation agency BEA said that, while it has yet to confirm the cause of the accident, the plane's Pitot probes were faulty.
The BEA agency's report said that Airbus, which built the missing A330 jet, had identified 32 cases between November 12, 2003 and the date of the crash in which two or more of these air speed monitors had iced up on its planes.
When Pitots are blocked by ice they send false speed measurements to the plane's onboard flight computers, as was the case on the missing flight, which sent a string of automated error messages before plunging into the ocean.
The BEA, which has already ordered airlines to replace the European-designed Pitots on their A330 and A340 Airbus jets with a US-made model, called in its latest report for new testing standards for the device.
"In practice, the testing criteria are not representative of the conditions really encountered at high altitude, in the case of temperatures for example," the investigators wrote.
"What is more, it seems that certain points -- for example the size of ice crystals inside cloud masses -- are not well understood and it is therefore difficult to evaluate the effects that could have on Pitot probes."
Pilots' unions and some of the relatives of victims of June's crash have accused Air France and Airbus of ignoring longstanding problems with air speed monitors on its jets in the run up to the June disaster.
The companies insist that their jets met all safety standards, but they have nevertheless now replaced the Pitots with a different model.
The BEA has said that the missing jet was receiving false speed data from its Pitots, as it flew at high altitude through a tropical zone known for dense cloud formations, but has not confirmed the cause of the crash.
Crash investigators have not been able to recover the AF447's black box flight data recorders from the ocean off Brazil, and the inquiry into the accident is continuing.
Date created : 2009-12-17
