EXPLAINER: Why did Nepal plane crash in fair weather?

BANGKOK (AP) — Yeti Airlines flight 691 crashed Sunday just before landing in Nepal's tourist city of Pokhara, the gateway to a popular hiking area in the Himalayas, after a 27-minute trip from Kathmandu.

At least 69 of the 72 people aboard have been confirmed dead.

Pilots say Nepal can be a challenging place to fly, but conditions at the time of the crash were good, with low wind, clear skies and temperatures well above freezing. So what might have caused the crash of the ATR 72 aircraft?

DID THE PLANE STALL?

A dramatic video shot on a smartphone from the ground shows the last moments before the plane crashed in a gorge about 1.6 kilometers (a mile) from newly opened Pokhara International Airport. The aircraft's nose is noticeably high before the left wing suddenly drops and the plane falls out of sight of the video, indicating a likely stall, said Amit Singh, an experienced pilot and founder of India's Safety Matters Foundation.

“If you see the trajectory of the aircraft, the aircraft's nose goes up, and the nose up would be associated with a reduction in speed,” he told The Associated Press. “When they have stalls, typically one wing goes down and wings are basically generating the lift. So as the air flow reduces, the lift generated is not enough to sustain the aircraft in flight and the wing drops and the aircraft nosedives.”

Professor Ron Bartsch, an aviation safety expert and founder of Australia's Avlaw Aviation Consulting, told Sydney's Channel 9 that he also thought the plane appears to have gone into a stall. Its proximity to the ground possibly made it look to the pilots like their speed was greater than it was, he said.

“I'd suggest that the aircraft has entered into an aerodynamic stall,” he said after reviewing the video just before the crash....