The two male passengers, wearing their seatbelts, were wincing as the wind whipped around them, while they clutched the armrests and tried and turn away from the door.
A 44-year-old passenger told Yonhap that it was "chaos" on the flight after the door was opened.
"It was chaos with people close to the door appearing to faint one by one and flight attendants calling out for doctors on board through broadcasting while others were running down the aisle in panic," the passenger said.
"I thought the plane was blowing up. I thought I was going to die like this."
A transport ministry official on the aviation safety team told AFP that this was "the first such incident" they were aware of in Korean aviation history.
South Korea's aviation industry has a solid track record for safety, experts say.
Asiana, which was established in 1988 as a rival to flag carrier Korean Air, was involved in a major crash in San Francisco in July 2013.
At that time, Asiana Flight 214 from Seoul clipped a sea wall with its landing gear, then crashed and burst into flames, killing three people and leaving 182 injured.
The troubled carrier is currently set for a takeover by Korean Air, which said in 2020 that it would buy out Asiana for $1.6 billion as the Covid pandemic wreaked havoc on the worldwide aviation industry.