Row Flares As Pilots Boycott Rio Crash Probe
Published: August 4, 2011
French pilots on Wednesday suspended cooperation with an inquiry into the 2009 crash of an Air France jet as a dispute over the causes of the disaster opened deep wounds in France’s prestigious aeronautics industry.
The SNPL airline pilots union declared the boycott after it emerged that crash investigators had removed a recommendation about one of the Airbus A330’s systems from an interim report last week, focusing instead on possible pilot error.
The BEA acknowledged the move but hit back at claims that the decision had cast doubt over its independence.
It said it had not abandoned the idea of making a recommendation on the A330 cockpit alarms but that the issue needed more work. Meanwhile in an unusual statement, it hammered out even more clearly the main question hanging over the pilots.
“The stall alarm rang out uninterruptedly for 54 seconds from the time the stall started without provoking an appropriate response from the crew,” the agency said.
The BEA said last week that crew had failed to respond to repeated stall warnings and listed a series of actions that experts said went against the handbook.
Its 10 recommendations included better training for pilots to fly aircraft manually, particularly at high altitudes.
The ongoing inquiry into what caused flight AF447 from Rio to Paris to crash into the Atlantic Ocean, killing all 228 people on board, has pitched France’s flagship carrier and its pilots against Airbus and crash investigators.
The outcome may have legal implications for dozens of potential compensation claims on both sides of the Atlantic.
“Why ignore in the official report the recommendation on the stall alarm? Were other significant modifications made to the report?” the SNPL said in a statement, noting that the BEA’s reputation had been “seriously shaken”.
An association for victims’ families said the BEA’s actions had undermined the credibility of the investigation.
STALL WARNING TRAP?
Despite posing questions over crew actions, the BEA has said it is still too early to say exactly why the A330 crashed, though its specialists have more or less pieced together how.
The autopilot switched off after the aircraft’s speed sensors became blocked with ice at night and high altitude.
Under manual control, the A330 rose sharply, lost speed and entered a stall, plunging from 38,000 feet with alarms sounding.
The BEA said last week the Air France pilots had not been trained to deal with the loss of reliable speed data at high altitude. Investigators are examining whether by solving one problem the crew lurched into a second that proved their doom.
Air France on Friday rejected the focus on its pilots and said they had been confused because the stall alarm kept going on and off. According to black box data, the plane’s stall alarm sounded 11 times but was not discussed.
Pilots have complained of a stall warning “trap” as the alarm can stop once the aircraft exceeds certain limits, only to start again once things improve and data can be measured.
Designers say that came to light only because the 200 tonne jet was flown into extremes that could never be foreseen, going more slowly than a plane a fraction of its size. Wednesday’s BEA statement however confirms investigators are worried about this.
Airbus refused to enter the fray, but people familiar with the Toulouse-based firm accused the French national airline and its pilots of trying to sink the inquiry by diverting attention from evidence set out in the black box tapes.
“Their only solution is to blow up the investigation,” said one source, asking not to be identified.
The stall alarm controversy marks the third wave of speculation about the cause of the crash, which focused first on possibly faulty speed sensors, then pilot error and now the technical rules for triggering a cockpit stall alarm.
Families and lawyers are not expected to get a definitive view on the crash until a final report late this year but some have complained that the focus on the speed sensors has faded.
France’s Transport Minister called the BEA probe “exemplary” and said it had been monitored by a French judge carrying out a parallel criminal investigation, as well as police, international observers and the parties involved.
“Let anyone show me an inquiry which has been as transparent as this,” Mariani said.
When an aircraft enters an aerodynamic stall, air stops flowing correctly under its wings and it can no longer fly.
Investigators want to establish not only whether pilots reacted wrongly to the stall warning but also how the USD$ 200 million aircraft came to be in such a hazardous condition.