FAA to temporarily ground certain Boeing planes after Alaska Airlines door blew off in midair

National Transportation Safety Board chair Jennifer Homendy said what happened was 'an accident, not an incident'

The Federal Aviation Administration announced a temporary grounding and inspections of certain Boeing 737 Max 9 planes after an Alaska Airlines flight was forced to make an emergency landing Friday night in Portland, Oregon, when a door blew out of the aircraft.

National Transportation Safety Board chair Jennifer Homendy said in a news conference that what happened was "an accident, not an incident."

Homendy said flight 1282, which had a target destination of Ontario, California, was forced to return to Portland International Airport just minutes after takeoff when a "mid-cabin door plug ... departed the airplane, resulting in rapid decompression." She said she will not speculate about the cause of the accident.

Nobody was sitting in the two adjoining seats next to the blown-out door.

ALASKA AIRLINES FLIGHT MAKES EMERGENCY LANDING IN PORTLAND AFTER SECTION OF PLANE BLEW OUT MID-AIR

Alaska Airlines Flight 1282 had been bound for Ontario, California and suffered depressurization soon after departing, in Portland, Oregon.

Alaska Airlines Flight 1282 had been bound for Ontario, California and suffered depressurization soon after departing, in Portland, Oregon. (Reuters)

The flight had 171 passengers, two pilots and four flight attendants. No serious injuries resulted from the accident, but some people suffered minor injuries. The airline reported that several passengers suffered injuries that required medical attention but that all of them have since been medically cleared.

"We are very, very fortunate here that this didn't end up in something more tragic," Homendy said.

"With that said, I imagine this was a pretty terrifying event," she added. "We don't often talk about psychological injury, but I'm sure that occurred here."

The door blew off at an altitude of about 16,000 feet, and Homendy said it was fortunate that the plane had not reached a cruising altitude of at least 30,000 when the accident occurred.

"Think about what happens when you're in cruise," Homendy said. Everybody's up and walking, folks don't have seatbelts on. They're going to restrooms. The flight attendants are providing service to passengers. We could have ended up with something so much more tragic."

WATCH: ALASKA AIRLINES PASSENGER CAPTURES HORRIFYING MOMENTS AFTER PLANE PART BLEW OFF MID-AIR

People sit on a plane next to a missing window and portion of a side wall of an Alaska Airlines Flight 1282.

People sit on a plane next to a missing window and portion of a side wall of Alaska Airlines Flight 1282. (Reuters)

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The blown-out door still has not been located. Homendy asked the public for help locating the door, saying it is believed to be in the western Portland metropolitan area near Oregon Route 217 and Barnes Road in the Cedar Mills suburb. 

The headrests for the two adjoining seats next to the door and the seatback for one of the seats were also destroyed.

"Each aircraft will be returned to service only after completion of full maintenance and safety inspections," the airline said in a statement.

FAA released a directive Saturday requiring safety inspections of 171 Boeing 737 Max 9 aircraft in operation around the world.

The Alaska Airlines aircraft was delivered from Boeing in October.

The NTSB's fact-finding stage will involve the FAA, Boeing, Alaska Airlines, the Airline Pilots Association and the Association of Flight Attendants. The investigation begins on Sunday.