AirAsia Flight QZ8501 may have pushed jet beyond limit

Radar data being examined by investigators appeared to show that AirAsia Flight QZ8501 made an “unbelievably” steep climb before it crashed, possibly pushing it beyond the Airbus A320’s limits, said a source familiar with the probe’s initial findings.

The data was transmitted before the aircraft disappeared from the screens of air traffic controllers in Jakarta on Sunday, added the source, who declined to be identified.

So far, the numbers taken by the radar are unbelievably high. This rate of climb is very high, too high. It appears to be beyond the performance envelope of the aircraft,” he said. The source added that the data on which those assumptions had been made were incomplete. Colleagues and friends of the Indonesian captain on board have described him as an experienced and professional pilot.

The findings sharpen the focus on the role bad weather and crew’s reaction to storms and clouds in the area had to play in the plane’s crash which killed all 162 people on board. Finding the plane’s cockpit voice recorder (CVR) and flight data recorder (FDR), more commonly known as black boxes, was vital to complement the radar data already available. “With the CVR and FDR, we can establish what went on in the cockpit and what was going on with the plane. We can conclude if the radar information is accurate,” the source said.

At 6.12am on Sunday, 36 minutes after taking off from Surabaya’s Juanda Airport, the pilot asked for permission to climb to 38,000ft from 32,000ft and deviate to the left to avoid bad weather. Two minutes later, Jakarta responded by asking QZ8501 to go left seven miles and climb to 34,000ft.There was no response from cockpit. The aircraft was still detected by the ATC’s radar before disappearing at 6.18am.

An image that was reportedly leaked from AirNav Indonesia, which manages the country’s air space, and shared on websites, appeared to show QZ8501 at an altitude of 36,300ft and climbing at a speed of 353 knots. The source declined to confirm if that image was accurate.

Two veteran pilots said that, if accurate, the image and information released so far pointed to the fact that the aircraft may have climbed suddenly and then lost speed. This can result in the aircraft stalling in mid-air before plunging to the sea, they said.

The source said other aircraft in the area at the time of the crash were flying at higher altitudes. Aircraft tracking website said, “We know that there was severe local weather and big clouds. But the other planes were higher and did not appear to encounter any major problems. We want to look into that too,” added the source.