Debris Tells Where but Not Yet Why Air France Jet Plunged to Its Doom
Wednesday, June 3, 2009
The swath of wreckage found in the Atlantic yesterday may have solved one mystery -- where Air France Flight 447 apparently went down -- but made another question yet more troubling.
How could a modern airplane simply drop out of the sky?
The Airbus A330-200, like most new aircraft, is largely controlled by computers and wires. Pilots guide the plane with joysticks rather than the conventional yokes that still dominate the image of piloting for most people.
Instead of heavy cables, the plane's flying systems are connected by wires, miles of redundant wires linked to computers that are constantly cross-checking one another. But the advanced A330, carrying 228 people, appears to have been little match for fierce thunderstorms over the tropics.
Aviation safety analysts yesterday continued to play down lightning as the force that doomed the French airplane, explaining that aircraft routinely encounter such strikes. French aviation officials have yet to fully detail what went wrong in the A330. But a struggle with a "complex of thunderstorms" is at the heart of current theories about the case.
"I think we are talking about an encounter with severe weather with the rest of the events happening afterward," said William R. Voss, president of the Flight Safety Foundation. "What remains to be understood is how did this encounter lead to the aircraft being lost?"
Based on data from the plane and infrared satellite images and other information, meteorologists and aviation experts say the A330 was met by a group of thunderstorms 400 miles off the coast of Brazil. The crew and passengers were nearly four hours into their flight, cruising on a northeast course to Paris at an altitude of 35,000 feet.
The storms were in their early stages, a period when they are typically most violent. The storms reached as high as 50,000 feet above sea level and packed 60- to 70-miles-per-hour vertical drafts. Aviation experts say the A330's pilots probably found themselves "boxed in" by storm conditions developing so rapidly that they were left with few options.
"It was probably a combination of circumstance that led to the demise of 447," said Ken Reeves, director of forecasting operations at Accuweather.com. "What the exact combination is, we're going to have to piece it all together."
The winds likely slammed into the plane causing severe turbulence, analysts say.
From there, many things could have gone wrong. With the turbulence jerking the plane up and down, the aircraft could have experienced rapid decompression. If the plane was hit by lightning, a window could have broken out. The turbulence could have resulted in an engine failure, or some failure that caused parts of the blades to break off and pierce the plane's hull.
About 15 minutes after entering the storms, the A330 began sending out automated maintenance messages indicating problems with electrical components and pressurization. The A330 was supposed to radio a report a few minutes later but never made the scheduled call.
With the plane's black box recorders still underwater, the satellite messages offer the investigators the best clues, said John Hansman, a professor of aeronautics and astronautics at the Massachusetts Institute of Technology.
"Once you look at them in detail, it will be possible to put together different hypotheses of what could happen," Hansman said.
Voss said the messages, along with the missing black box recorders, could resolve the mystery. He said the goal of safety investigators is to learn from crashes and to add new layers of safety to the system. Investigators from around the world will want to know precisely what went wrong on the Flight 447. The A330-200 and the larger A330-300 are popular jets in the industry, with strong safety records, analysts say.
"It's not like we didn't know that flying through a thunderstorm was a bad thing," Voss said. "We've known this for decades -- that thunderstorms need to be avoided at all costs. The question is why did the pilot have to fly though this thunderstorm and is there anything we could have done that would have made the aircraft more survivable?"