AirAsia flight QZ8501: Radar data shows 'unbelievably steep climb' before crash
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.
The data was transmitted before the aircraft disappeared from the screens of air traffic controllers in Jakarta on Sunday, said a source familiar with the probe's initial findings.
“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 first victims arrived on land in coffins in Indonesia today
Finding the six-year-old 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 aircraft. We can conclude if the radar information is accurate,” added the source.
At 6.12 am on Sunday, 36 minutes after taking off from Surabaya's Juanda Airport on a flight to Singapore, the pilot asked for permission to climb to 38,000ft from 32,000ft and deviate to the left to avoid bad weather.
A child writes a post-it note on a board of well wishes for the passengers at Changi airport in Singapore
An image that was reportedly leaked from AirNav Indonesia, which manages the country's air space, and shared on several 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 and officials from AirNav Indonesia declined to comment.
Two veteran pilots told Reuters 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.
An Indonesian Navy helicopter assists in the search for debris from AirAsia flight QZ8501 near Batam, south of Singapore
“If you encounter turbulence, you go slower at what we call the turbulence penetration speed to get through it. If you climb to avoid turbulence, you slow down to have a better climb rate. That could be around Mach 0.76,” he said. “But if you climb suddenly and start to lose speed, you will stall.”
The source close to the probe said other aircraft in the area at the time of the crash were flying at higher altitudes. Aircraft tracking website flightradar24.com said that they were at between 34,000 and 39,000 feet.
“We know that there was severe local weather and big clouds. But they (the other planes) were higher and did not appear to encounter any major problems. We want to look into that too,” added the source.
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