May 12, 2007

Doomed Jet Took Off While Others Waited

Three jetliners sat ready for takeoff at Douala International Airport, their crews waiting for a massive thunderstorm to move away.

Just a few minutes past midnight, all three radioed air traffic control to check the weather report. They were told the storm would take another hour to dissipate, and the Cameroon Airlines and Royal Air Maroc crews opted to wait it out.

But Capt. Francis Mbatia Wamwea of Kenya Airways Flight 507, already delayed for an hour and carrying scores of passengers with onward connections to catch, judged the weather had improved sufficiently to permit departure for Nairobi, Kenya.

Less than a minute after takeoff early on May 5, the Boeing 737-900 slammed into a jungle swamp during a raging storm, killing all 105 passengers and the nine-member crew.

The dead included Dr. Albert Henn, an AIDS expert who worked at Harvard University and had a home in Barnstable, Mass.; businesspeople from China, India and South Africa; Cameroonian merchants; a Tanzanian returning from peacekeeping duties in Ivory Coast; a U.N. refugee worker from Togo; and Anthony Mitchell, a Nairobi-based correspondent for The Associated Press.

The six-month-old plane was of the newest generation of the world's most popular airliner, which has an excellent safety record. It was only the second time a 737-800 has crashed with the loss of all on board. In September, a plane belonging to Brazil's Gol Airlines collided with an executive jet over the Amazon jungle, killing 154.

After Wamwea gave the go-ahead, the Kenyan Airways crew radioed the tower, pulled away from the gate, and taxied toward Runway 12, heading roughly southwest from the airport. The Douala tower cleared the flight for takeoff a few minutes later, instructing it to report on reaching 5,000 feet.

The pilot acknowledged the clearance from the tower. It's unclear what time that final voice transmission was received from the jet, but the plane nose-dived into a swamp on the outskirts of Cameroon's commercial hub only 30 seconds after becoming airborne.

Wamwea's decision to depart into one of the violent tropical storms that regularly ravage equatorial Africa during the rainy season was most likely the pivotal factor in a sequence of events that led to the crash, said a Cameroonian investigator and a government pilot assisting the probe of Flight 507, both speaking on condition of anonymity because the inquiry was still under way.

Kenya Airways chief executive Titus Naikuni said investigators would have to make the final assessment. The probe was likely to take months.

"We don't want to start speculating here," he said Friday in Kenya. "So whether the pilot did the wrong thing or the right thing, I cannot answer that."

Investigators said they cannot yet discount other factors, including mechanical failure, pilot disorientation or even sabotage. But no sign of a blast or fire has been found so far by the search teams, which include seven experts from the U.S. National Transportation Safety Board and two Boeing representatives.

Flight crews are responsible for the decision whether to take off or land in bad weather, usually depending on guidelines from their airline. And while air traffic control can take measures to halt flights, including closing down airports, such drastic actions are highly unusual outside the northern hemisphere, where heavy winter snows can block runways and bring traffic to a standstill.

The Douala airport is not equipped with weather radar, but the 737-800 is. Pilots routinely take off into stormy weather and then rely on radar to guide them around the towering thunderheads that can cause structural damage to aircraft.

Wamwea, 53, was an experienced flier with about 8,500 hours on jets. He had joined Kenya Airways 20 years ago and enjoyed the reputation of a diligent and professional pilot.

The co-pilot, Andrew Kiuru, was only 23 and had joined the airline a year ago after completing flight school in South Africa.

The cockpit voice recorder has not been found, so no details of the final exchanges between Wamwea and Kiuru are available. It remains unclear who was flying the plane at the time, but Wamwea would have had the ultimate authority.

The flight data recorder has been recovered.

Two minutes after Flight 507 would have been expected to reach 5,000 feet, the point at which it had been instructed to check in, Douala Area Control Center issued a distress message. This is normal practice by air traffic control when unable to establish immediate contact with an aircraft, a frequent occurrence. But controllers, who had lost sight of the plane fairly quickly because of the storm, were not unduly worried because the plane had fuel for six hours of flying time.

A search was launched at 2:44 a.m. when a French radar station sent in a message that an airplane distress signal had been picked up. A Cameroonian air force plane and two helicopters first flew over a region far to the south, basing their search on the distress signal that was in fact hundreds of miles away from the actual crash.

It is unclear why the signal was so far off the mark, but it appears the plane's emergency locator beacon's final signal was garbled - indicating a false position.

The wreckage was found 40 hours after takeoff by a hunter who chanced upon it in a mangrove swamp. The site is less than 3 1/2 miles from Runway 12. Experts calculate that the plane was in the air for only 30 seconds and had never climbed over 3,000 feet.

Commercial jets regularly fly over the area, one of several standard departure routes from Runway 12. Villagers living nearby said they heard planes passing overhead during the night - and a particularly loud boom that sounded like a thunderclap.

Since there were no witnesses to the crash, investigators have pieced together the known facts and formulated several theories on what could have happened.

The wreckage indicated the plane flew nose-first into the ground at a nearly 90-degree angle. It was found buried deep in a crater of reddish-brown muck with only tiny bits of the rear fuselage and wings left above ground. Trees nearby were smashed, but otherwise the jungle canopy was intact, making the site almost invisible from the air.

Investigators said the nose dive indicated that a violent gust of wind may have flipped the airliner over, throwing it into a fatal fall. Although modern jets can usually fly through storm clouds, storms in Africa are particularly violent at this time of the year, investigators said.

The location of the wreckage also indicates the pilot was banking sharply to the right. This would have exposed the raised left wing to the gust, investigators said.

The low altitude would have made it impossible to recover from the resulting dive.

By SLOBODAN LEKIC, Associated Press Writer

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