Even if the black boxes from flight AF447 are found, investigators may not be able to solve the crash
A QUESTION MARK hangs over one of the world’s most popular long-haul aircraft. Does the A330 harbour a lethal flaw? And do we really know enough about the impact of storms on jets? Reassuring passengers, or condemning the aircraft, will be the job of France’s Bureau d’Enquêtes et d’Analyses pour la Sécurité de l’Aviation Civile (BEA). Its investigators face a gargantuan task, with no guarantee that they will produce an answer. The wreckage is in the ocean, there are no witnesses and few clues.
If it is recovered, and there are strong hopes it will be, the flight data recorder (FDR) will enable BEA investigators to reconstruct almost every second of the aircraft’s final hours. Not only will they learn what the aircraft, its engines, flaps and rudder did, and where, they will also find out what controls were used by the pilots.
Investigators will be able to fly a virtual A330 using a simulator and piece together the last minutes it spent in the air. But even if the FDR is found, there is still no guarantee that a probable cause for the crash will emerge. All the FDR might say is what the aircraft did, not why. The same applies to the data transmitted automatically to Air France via satellite as, one by one, the aircraft’s systems failed. We know they failed, but not why.
If the cockpit flight recorder (CVR) is retrieved from the ocean floor, hearing what the pilots say to each other may help fill gaps in the jigsaw. But that assumes they say anything intelligible; in previous accidents pilots have been too startled or too busy attempting to control the aircraft to voice their concerns.
Yet, the ingenuity of investigators knows few boundaries. When, because of flawed rudders, two US Boeing 737 aircraft crashed in 1991 and 1994, among the most meaningful things that investigators heard on cockpit tapes was a pilot grunting. That led them to conclude that whatever he was doing required immense effort, lending support to a theory that his rudder pedal had jammed.
When a cargo plane that had a broken FDR crashed on takeoff, a US investigator was still able to compare the background noise of its tyres and engines on the tapes with those of similar aircraft on the same runway and to calculate take-off speed. It was moving too slowly to make it into the air.
However, there are some things data recorders and tapes can never reveal. Unless the pilots are heard discussing it, there may be no record of ice on the wings, or of a tropical deluge sucked into the engines, extinguishing them. A lightning strike should leave traces on the aircraft’s skin, or a bomb explosion leave tell-tale chemical residues, but the vital part containing those clues might not be found.
Without enough wreckage, many aircraft disasters would not have been solved, and further crashes prevented. Solving a series of mysterious crashes befalling the early 1950s Comets, a fatal flaw in the DC-10 hydraulics, a weakness in A300 tailfins and the misbehaving 737 rudders all depended on a painstaking reconstruction of at least portions of an aircraft. A reconstruction of the remains of TWA flight 800 dredged from the relatively shallow water of Long Island Sound in 1996 enabled investigators to prove it disintegrated because of a fuel tank explosion, not a bomb.
It is highly unlikely that sufficient wreckage from flight AF447 will be recovered to attempt a similar reconstruction, so the possibility remains that this crash might never be solved. In that case a report, citing undetermined causes, might be issued but crash investigators don’t easily admit defeat.
When, after many months of probing, the National Transportation Safety Board failed to solve the crash of flight 581, a Boeing 737 which mysteriously crashed in Colorado Springs in 1991, such a report was issued but investigator Greg Phillips didn’t give up. He kept detailed files on every 737 accident and incident until, a decade later, he was a leading part of the team which finally revealed that flawed rudder hydraulics were responsible.
Investigators will almost inevitably face determined pressure from vested interests. During the 737 rudder investigation, Boeing made convincing arguments that freak weather was to blame. It also produced reports of car accidents where drivers hit the accelerator pedal instead of the brakes, to suggest the pilots probably stamped on the wrong rudder pedal.
It is plausible that Airbus will hope the weather, or pilot error will be blamed and its aircraft will be vindicated. Air France, on the other hand, will fear a finding that blames pilot or maintenance error, leaving them open to massive lawsuits. And the worst possible outcome for everybody would be if, before this crash is solved, another A330 vanishes over the ocean.
Gerry Byrne is the author of Flight 427: Anatomy of an Air Disaster(Copernicus Books, New York)