Official: AirAsia jet climbed too fast before crash

John Bacon | USA TODAY

Show Caption Hide Caption AirAsia crash not the result of terrorist attack Aviation investigators rule out terrorism in the crash of AirAsia flight 8501. Julie Noce reports. Video provided by Reuters

Doomed AirAsia Flight 8501 streaked upward at fighter-jet speeds before suddenly plunging, vanishing from radar and plummeting into the Java Sea, Indonesian Transportation Minister Ignasius Jonan said Tuesday.

Jonan, speaking at an Indonesian parliament transportation hearing, said the average speed of a climbing commercial jet is 1,000 to 2,000 feet per minute. He did not say why the Airbus A320-300 would have suddenly climbed at a rate of 6,000 feet per minute, as radar data showed.

Such rapid ascents can cause commercial jets to stall.

"It is not normal to climb like that," Jonan said. "It can only be done by a fighter jet."

Minutes before the crash, the pilot had asked air-traffic controllers to increase altitude 6,000 feet, to 38,000 feet, citing severe weather. The request was denied because of heavy air traffic in the area.

Peter Goelz, a consultant and former managing director of the National Transportation Safety Board, told USA TODAY he was "skeptical" that the plane could even perform the climb that Jonan described.

"But the Indonesians have been very sober throughout this investigation — and information they have provided has been dead-on," Goelz said. "I have been impressed with them."

Such a high climb rate could be consistent with severe updrafts in a strong thunderstorm, said Les Westbrooks, associate professor of aeronautical science at Embry-Riddle Aeronautical University in Daytona Beach, Fla., and a former American Airlines pilot.

Storms in that region can grow particularly tall, he said. A commercial jet crew would not normally try to climb at such a speed, he said, and it's unlikely a pilot would try to climb over a thunderstorm. Regardless of instructions from air traffic control, a pilot could declare an emergency and deviate course to go around such a storm, he said.

"It would be highly unlikely that a seasoned air crew would just pitch up and climb at 6,000 feet per minute,'' he said. "If they inadvertently got into a thunderstorm, that would be exactly the characteristics of what would happen.''

Passengers would likely feel strong turbulence in such a climb, and the aircraft could go into an aerodynamic stall if the plane failed to keep wind moving over its wings above a minimum speed required for flight, he said. Hail from such a storm could pose a severe threat to an aircraft as well, he said.

"At that altitude, commercial jetliners ... don't climb at 6,000 feet per minute,'' Westbrooks said. "They could for a very short amount of time.''

Paul Kelly, adjunct professor of aviation at San Jose State University and an Airbus captain with United Airlines, said the flight data recorder should reveal how suddenly the climb took place and the amount of G forces exerted on the aircraft and its passengers.

"A thunderstorm could do it, with severe updrafts and downdrafts, which is basically why you don't go into thunderstorms if you can avoid it,'' Kelly said.

The Singapore-bound Airbus A320-300 crashed Dec. 28 less than an hour out of Surabaya, Indonesia's second-largest city. All 162 passengers and crew were killed. The fuselage, tail and black boxes have been located, but more than 100 bodies remain at the bottom of the choppy, murky sea.

No distress signal was received and the cause of the crash had not been determined.

"So far, we've managed to download and transcribe half of the cockpit voice recorder," said Nurcahyo Utomo, a commissioner with Indonesia's National Transportation Safety Committee. "It is too early to draw any conclusion yet because we don't know what is in the remaining half."

He said there was no indication of terrorism and no voices on the recorder other than those of the jet's crew.

The Transport Ministry has said AirAsia did not have a license to fly the route on the day of the crash, a claim AirAsia Indonesia initially disputed. Last week, however, airline president Sunu Widyatmoko acknowledged that due to an "administrative mistake" the airline had only verbally proposed a schedule change to allow Sunday flights.

The airline has been banned from flying the Surabaya-Singapore route. The Transport Ministry has suspended scores of routes from other domestic airlines for similar alleged violations.

Contributing: William M. Welch in Los Angeles; the Associated Press