A flight data recorder has been found from the wreckage of a Bangladeshi passenger plane that crashed on Monday afternoon near the airport in Nepal’s Capital Kathmandu. Forty-nine people died in the crash. An investigation into what causes the crash has started, Reuters quoted the airport’s General Manager Raj Kumar Chettri as saying.

The US-Bangla plane was carrying 71 people, of whom 33 passengers were Nepali, 32 were Bangladeshi, and one each were from China and the Maldives. The accident is believed to be Nepal’s worst aviation disaster since a Pakistan International Airlines aircraft crashed in 1992, killing 167 passengers.

The airline and airport authorities have blamed each other for the crash. A radio conversation between the air control tower and the pilot of the plane was posted on liveatc.net, AP reported.

“We suspect wrong signals from Kathmandu air traffic control room might have led to the crash,” US Bangla Airlines Chief Executive Imran Asif said, according to Reuters. “A three-minute conversation between the pilot and the air traffic control before the landing indicated that they sent a wrong signal to the pilot.”

However, airport authorities claimed that the pilot had ignored the control tower’s instructions and approached the runway from the wrong direction. “The airplane was not properly aligned with the runway,” Chettri said. “The tower repeatedly asked if the pilot was OK and the reply was ‘Yes’.”

Defending the pilots, the airlines said Captain Abid Sultan, who survived the crash, had more than 5,000 hours of flying experience and was specially trained to land at the airport. Sultan is a former Bangladesh Air Force pilot and was also a flying instructor with the airline, AP reported.

The Nepali government has also ordered an investigation into the crash.