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Was Air France flight brought down by turbulence or hail?

100 m.p.h. winds, hail, and rain might have brought Flight 447 down, says a former Air Force meteorologist.

By / June 2, 2009

Was Air France flight 447 brought down by a 100 m.p.h. updraft?

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Or were its two jet engines snuffed out by hail or heavy rains?

In the absence of a black box, the leading theory now is that the Airbus 330-200 was brought down by a 300-mile-wide band of tropical thunderstorms that it could fly neither around nor over.

Brazil's defense minister confirmed Tuesday afternoon that military planes found a three-mile path of wreckage in the Atlantic, hundreds of miles from Fernando de Noronha, a Brazilian archipelago.

Professional pilots and meteorologists are digging through the available data – flight routes, satellite images, aircraft specifications, and weather reports – and spinning out several likely causes.

One of the most detailed and cogent pieces of analysis of Flight 447’s last minutes – winning the praise of pilots around the world – is a blog by Tim Vasquez.

Mr. Vasquez is a former US Air Force meteorologist. He now consults and publishes weather forecasting texts and software.

Vasquez plots the likely flight path of Air France 447 and overlays it on satellite imagery and weather reports in the area at the time:

It appears AF447 crossed through three key thunderstorm clusters: a small one around 0151Z, a new rapidly growing one at about 0159Z, and finally a large multicell convective system (MCS) around 0205-0216Z. Temperature trends suggested that the entire system was at peak intensity …

Air France says that it received an automated message from Flight 447 reporting electrical faults and loss of pressurization. Vasquez says that message was sent just as the jet was nearing the final edge of the storm cells, but after being battered by turbulent updrafts as high as 100 mph for about 12 minutes (or 75 miles).

Several pilots, in comments on his site, agree that turbulence was probably a factor., a private forecasting firm, issued a statement Tuesday, offering a similar theory based on its own data:

The plane appears to have flown into or near a large cluster thunderstorms that were in the development stages northeast of Fernando De Noronha, which is located off Brazil's northern coast, and along the Intertropical Convergence Zone (ITCZ), the belt of low pressure that surrounds the Earth at the equator.
Based on weather information from Fernando De Noronha, the updrafts associated with the thunderstorms may have reached up to 100 m.p.h. Such an updraft would lead to severe turbulence for any aircraft. In addition, the storms were towering up to 50,000 feet and would have been producing lightning.

At its last check-in time, the Air France aircraft was flying at 35,000 feet. A check of the Airbus 330-200 specifications shows that the aircraft has a ceiling of 41,000 feet.

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