Dubai - An Emirates airliner that crash landed in Dubai on Wednesday tried to regain altitude in the last moments before it hit the ground, transponder data and air traffic control communications suggest.
The airline and investigators have not confirmed the findings, and aviation experts caution that much remains unknown about the cause of the crash.
But the data, if confirmed by the plane's black boxes, indicate the crew of Flight EK521 was starting to go around for a second landing attempt when something went horribly wrong.
Transponder data from the Boeing 777-300 obtained by aviation website FlightRadar24.com show the descending plane came close to the ground at 12:37 local time before altitude readings and the vertical speed suddenly increased, indicating the start of a go-around.
That came around the same time an air traffic control radio recording has someone calling out the flight's number and saying "returning to 4 000".
"I think it indicates that there was some kind of effort to try to gain altitude," Mikael Robertsson, a co-founder of FlightRadar24, told The Associated Press.
But within 12 seconds, the aircraft descended and struck the ground, apparently bouncing back up briefly before coming down and stopping, according to the data.
At the time of the crash landing, the scorching mid-day sun had raised temperatures at the airport to a humid 49°C. Barefoot passengers fleeing the plane said they burned their feet on the scalding tarmac.
While that's not an unusual temperature for this time of year, the hotter the conditions are, the harder it can be for engines to lift planes off the ground, according to experts.
Winds of 39km/h blew toward the northwest at the airfield at the time of the crash-landing, according to the United Arab Emirates' National Centre for Meteorology and Seismology.
The possibility of wind shear - a sudden change in wind speed or direction - is also being looked into by investigators, Emirates CEO and chair Sheikh Ahmed bin Saeed Al Maktoum has said.
An attempted go-around could explain why the grounded plane's landing gear did not appear to be extended.
"If the plane had gone around, part of the manoeuvre is retracting the landing gear," said commercial airline pilot and author Patrick Smith.
"It's conceivable that during the go-around that they experienced a dangerous wind shear," he said.
John Gadzinski, an airline captain and aviation safety consultant, agreed that the transponder data was consistent with an attempted go-around by the crew.
He cautioned, however, that the readings are not as precise as those on the plane's own flight data recorder, and that investigators will need more information to determine what went wrong.
Emirates officials have repeatedly declined to say definitively whether the plane was attempting to go around and whether the landing gear was properly deployed.
The UAE's General Civil Aviation Authority, which is leading the investigation, said on Thursday it was still working to recover the flight data and cockpit voice recorders.
American and British investigators will participate in the probe because the Boeing plane was built in the US and was powered by British-made Rolls-Royce Trent 800 engines.
Chicago-based Boeing said it is prepared to deploy a technical team to assist with the investigation in co-ordination with the US National Transportation Safety Board. It referred queries on the investigation to the GCAA, which plans to issue a preliminary report on the crash within a month.
The crash continued to snarl travel plans well into Thursday.
Charred carcass of plane removed
Dubai International Airport, the world's busiest in terms of international traffic, said it was running "under restricted capacity and has since continued to operate with one runway". Some flights were being redirected to the city-state's second airport, Al Maktoum International Airport at Dubai World Central.
By Thursday night, investigators had removed the charred carcass of the plane from the runway and reopened the affected runway, Dubai Airports CEO Paul Griffiths said. The crash-landing did little damage to the runway itself as the plane came to rest and burned off to the side of it, he said.
Flight EK521 was carrying 282 passengers and 18 crew on its return from Thiruvananthapuram, India.
Emirates said 157 passengers stayed in Dubai following the accident, while the rest remained in transit at the airport. Five who suffered minor injuries were taken to local hospitals, the airline said. A cabin crew member was hospitalised and was expected to be released on Thursday.
"They were very fortunate to get everybody out. That's a very positive thing to the cabin crew and to the design of the plane," Gadzinski said.
A firefighter, Jassim al-Balooshi, was killed in an explosion while battling the blaze. He was buried on Thursday in the emirate of Ras al-Khaimah.
The GCAA meanwhile issued a warning on Twitter for people to stop "publishing videos, news or pictures of aviation's accidents".
"Sharing such practices is considered to be irresponsible and disrespectful to the victims, and is punishable under #UAE law," the authority said.
The UAE, while liberal compared to many Mideast nations, has stiff penalties for those convicted of publishing photos of someone without their consent or offending them.
That call may be a little late, considering the worldwide attention on the accident. It came as an online video apparently made immediately after the crash circulated showing the chaos inside the plane.
In the footage, some passengers frantically reach for dangling oxygen masks even though the plane has come to a stop. Over the loud speaker, a man's voice calmly calls out: "Cabin crew, this is the captain: evacuate, evacuate."
Light grey smoke fills the cabin as some grabbed personal belongings in the overhead bins.
"Please don't do that! Leave everything!" another man shouts, presumably a member of the flight crew. "Leave the bag! Jump and slide!"
Another crew member runs past empty rows of seats, likely checking for anyone left behind. The camera shakes as a woman's voice screams for passengers to jump down an inflatable emergency slide.
Finally, bright light fills the video as the person filming comes outside the plane, pausing only for a moment to look at a burning jet engine on the damaged plane's wing before fleeing to safety.