After man opens plane door mid-flight, flyers ask: How can that happen?

A South Korean man faces 10 years in prison after he allegedly opened an emergency exit door while the plane was still in the air preparing to land.

The incident had flyers on Friday asking: How could that happen?

The aircraft landed safely at the Daegu airport, but officials said 12 people were taken to the hospital for respiratory issues.

The Asiana Airlines Airbus A321 was reportedly about 800 feet above the ground when the passenger opened the door.

Witnesses told local media other passengers tried to restrain the passenger.

Dramatic video shows extreme wind blowing passengers in the final moments of the flight.

Opening an aircraft door is impossible while the plane is at cruising altitude or above 10,000 feet due to air pressure.

However, as the plane gets lower, experts say it is possible for a door to open as the pressure outside equalizes with the pressure inside the plane.

"At cruising altitude there is enough pressure inside the cabin that it pushes the door against the hull of the airplane but, as the airplane descends, then the pressure begins to equalize. It is possible at very low altitudes as we've seen here for that door to be opened while the aircraft is still in flight," ABC News contributor and former Marine Col. Steve Ganyard explained.

"The fact that this happened in very low altitude just prior to touch down means that everybody should have been belted in. Nobody was going to get sucked out of the airplane but the person who opened the door certainly was in danger of falling out," he said.

The Asiana Airlines flight had 194 passengers and six crew members on board.

South Korean transportation officials say they are investigating exactly how the door opened.

Officials have not released a motive, but said the man did not appear to be intoxicated.

The domestic flight was traveling to Daegu from the resort island of Jeju.