Alaska Airlines plane whose door panel blew off midair was scheduled for maintenance

The Alaska Airlines plane that had a door panel fall off midair in January had been scheduled to undergo maintenance later that night, the airline confirmed Tuesday.

The incident on Flight 1282, which took off from Portland, Oregon, at 5:07 p.m. Jan. 5, resulted in no serious injuries but sparked an investigation that revealed no bolts were installed on the door plug of the Boeing 737 Max 9 aircraft.

The New York Times reported earlier Tuesday that the plane was scheduled for a safety check after some engineers and technicians became concerned — including about a light indicating problems with the plane’s pressurization system — and that it was kept in service with some restrictions.

Alaska Airlines told the newspaper that the warnings it had on the plane did not meet its standards to immediately take it out of service.

Alaska confirmed to NBC News that the plane was scheduled to head for maintenance later the night of Jan. 5.

The airline said in a statement that it, like other airlines, relies on "redundant systems, robust processes and procedures, and the willingness to stop and ensure things are right before every takeoff," and it said safety guides its decisions.

Flight 1282 was on a path from Portland to Ontario, California, when the door plug blew out at around 16,000 feet, officials said. The plane returned to Portland. Oxygen masks deployed as the plane made an emergency return.

Boeing has been under scrutiny following the failure of the door plug, which is a panel that seals where a door would be and makes it part of the fuselage. Some Boeing 737 Max 9 planes were temporarily grounded, and Boeing ousted the executive in charge of the 737 Max program.

The door plug was later found in the backyard of a Portland-area home.

The plane was delivered to Alaska Airlines on Oct. 31, and the airline put it into service on Nov. 11, the National Transportation Safety Board said in a preliminary investigation report.

The plane had 510 flight hours and 154 cycles, which is a flight from takeoff to landing, the agency said.

"We remain confident in our maintenance and safety actions leading up to the incident," Alaska Airlines said in the statement Tuesday. "We look forward to continuing our participation in a robust investigation led by the NTSB to ensure something like this never happens again."

There were 177 people aboard the plane, including flight and cabin crew members, and when the door plug fell off, it caused a rapid decompression, the NTSB said.

Seven passengers and a flight attendant sustained minor injuries, it said.

The NTSB announced Tuesday it will hold an investigative hearing on Aug. 6 and 7.