KATHMANDU — Recordings show apparent confusion between the pilot and air traffic control over the runway approach at Kathmandu airport as Nepal on Tuesday began investigating its deadliest plane crash in decades.

Aviation authorities said they had recovered the flight data recorder from the charred wreckage of the plane, which burst into flames after crashing into a football field near Kathmandu airport on Monday killing 49 people.

Witnesses have described how the US-Bangla Airways plane carrying 71 people abruptly changed direction moments before it crashed.

On Monday the airline’s chief executive Imran Asif said there had been a “fumble from the control tower” as the plane approached the airport’s single runway.

But airport manager Raj Kumar Chhetri said it was too early to say what had caused the mountainous country’s deadliest crash since 1992.

“It is yet to be identified whether the pilot or air traffic control was wrong,” he said, adding the investigation would be carried out with Bangladesh.

Recordings of the conversation between air traffic control and the pilot appear to indicate confusion over which end of Kathmandu airport’s single runway the plane was to approach.

Air traffic control can initially be heard clearing the plane to land from the southern approach.

“You are going towards runway 20,” the controller is heard saying seconds later, referring to the northern end of the tarmac.

A series of confused messages follow just before the crash in which the pilot says they will land at “runway 20” and then “runway 02” — the southern end.

“There is certainly considerable confusion from air traffic as to which runway the aircraft actually wants to land on,” said Britain-based aviation expert Andrew Blackie, who has reviewed the recordings.

Survivors said the pilot gave no warnings as the plane abruptly changed direction.

“I had asked the airhostess, what is happening, is everything fine? She gave a thumbs up, but I could see she was panicking,” said Ashish Ranjit, 35, who escaped through a window on the plane’s right.

“It was so low and it took such sharp turns.”

One survivor recalled the fire, but not how he made his way out of the aircraft.

“After the crash I was trying to [get] out of the plane because it was on fire but I could not, my hand and leg was trapped,” Keshav Pandey told BBC Nepali.

“I was on the seat by the side of the emergency door, [so] maybe I fell outside when [security came] and they opened the door. After that I don’t remember anything, I was unconscious.”

Another survivor also described the moment of impact to BBC Nepali.

“There was a huge fire outside and smoke gushed into our cabin. Then there was [an] explosion. The fire was extinguished and we were rescued outside,” Sharin Ahmed, a 29-year old teacher from Bangladesh said.

“All of a sudden the plane shook violently and there was a loud bang,” Basanta Bohora said from his hospital bed. “I was seated near a window and was able to break out.”

“The plane was going up down, right and left, up down. So I thought that was some air traffic only,” Sanam Shakya, who also escaped through a window, told AFP.

Shradha Giri, who was on board a nearby plane with her daughter, told the BBC: “There was a lot of chaos out there, lot of security personnel running towards it, a lot of ambulances and fire trucks approaching the site where it had crashed.”

“It was traumatizing just to be with my little girl out there...everybody was shaken up because just something like that to happen in front of your eyes.”

The plane hit the runway and skidded through an airport fence, leaving a trail of fuel and coming to a stop in a field where it burst into flames.

Twenty-two passengers — mostly sitting on the plane’s right side — managed to free themselves from burning wreckage by climbing through the plane’s windows or were pulled from the fuselage by passengers and rescuers. — Agencies