The unexpected opening of an emergency exit door on an Asiana Airlines plane making its landing on Friday in Daegu, South Korea, left passengers shaken, and nine of them were hospitalised after they experienced difficulty breathing.

The police arrested a man in his 30s on suspicion of forcing open the door. The suspect, who could face charges of violating aviation security laws, did not reveal a motive, said Kim Hyeong-su, an officer in the criminal affairs division of the Daegu Dongbu Police Station.

The plane, which left Jeju Island at 11:58am, was at an altitude of 700 feet and minutes from landing at 12:38pm, when a man seated in the emergency exit row next to the door forced it open, a spokesman for the airline said. According to FlightAware, the plane was travelling about 273km an hour at that point in the flight.

Normally when a plane is mid-flight, the difference in air pressure inside and outside the cabin prevents the doors from opening. But the plane was so close to the ground that the difference was negligible, allowing the door to be unlatched, said the airline spokesman, Baek Hyunwoo.

The crew members could not stop the man because the nearest flight attendant was seated too far away to reach him in time, and all on board — crew and passengers — must wear safety belts during landing, he added.

The plane landed safely, Baek said, and there were no major injuries among the 194 passengers and six crew members.

But 12 people — all but one of them between the ages of 11 and 16 — had hyperventilated, a spokesman for the Daegu Fire and Safety Department said. Nine of those were taken to nearby hospitals.

New York Times News Service