Into the storm

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Remains of the day: Brazilian Army personnel with casualties from flight AF447.
Remains of the day: Brazilian Army personnel with casualties from flight AF447.

What made the crew of ill-fated AF 447 fly into an active and dangerous weather system?

On June 1, 2009, AF 447, an Airbus 330 flight, departed from Rio De Janeiro for Paris. The flight had a compliment of three crew in the cockpit — A captain and two co-pilots. When the flight time is longer than the maximum permitted duty time limit for pilots, some countries permit an additional crew member so that the limit is not exceeded by rotating the duties. Normally, when one captain and two co-pilots are used, the captain would be in his seat during take off and the first portion of the flight and return prior to commencing descent for the landing. During cruise, the cockpit will be manned by two co-pilots.

Probable scenario

Four and a half hours into the flight, it is likely that the captain would have retired to the crew rest area. Just before leaving the Brazilian airspace, the crew reported encountering severe turbulence to the air traffic control. Sometime later, when they were to report leaving the Brazilian airspace, there was no contact. A few minutes before that, there were a flurry of failure reports transmitted by the Aircraft Communication And Reporting System (ACARS) to the Air France maintenance. The reports indicated that the aircraft had lost the complete autoflight system and electrical power. The crew had to fly the aircraft manually, without any of the safety protection devices available. It is also likely that the cockpit was manned by two co-pilots.

The flight was passing through an area called ITCZ, Inter Tropical Convergence Zone, which extends approximately 600 km to the north and south of the equator. The weather conditions can be extremely violent and satellite images taken at the time the aircraft disappeared indicated a huge thunderstorm in that area. The wreckage of the aircraft was found several days later. The speed sensors of the aircraft were suspected to have malfunctioned in the heavy icing layer inside the thunderstorm area as well as heavy precipitation. The French authorities are yet to locate the black boxes which would be the only confirmation on what really happened.

The startle factor

It is quite likely that if the two pilots in the cockpit were the co-pilots, as the body of the captain was one of those which were found, they would have been overwhelmed with the extreme weather conditions. Coupled with multiple failures of the aircraft system, they may not have been in a position to handle the resultant emergency. Overcorrecting the aircraft controls in a thunderstorm would have stressed the structure beyond its limits.

If the crew had got into the leeward side of the thunderstorm cloud which towered over 55,000 feet, the severe downdraft would have resulted in rapid speed drop. The ambient temperature would have resulted in thrust decay which would have further dropped the speed. The resultant “Jet upset” might have caused the aircraft to spiral down for a crash-landing in the ocean. All 228 on board were killed.

Several flights which passed through the same area, before or after the fatal flight, had taken deviations up to almost 100 miles to avoid this weather system. They had all reported turbulence. It is a mystery as to what made the crew of the fatal flight to proceed into the active weather system. If they had been experienced, would they have even ventured close to the danger? This will remain a mystery until the flight recorders are found.




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