Alaska Airlines Flight Was Scheduled for Safety Check on Day Panel Blew Off

A day before the door plug blew out of an Alaska Airlines flight on Jan. 5, engineers and technicians for the airline were so concerned about the mounting evidence of a problem that they wanted the plane to come out of service the next evening and undergo maintenance, interviews and documents show.

But the airline chose to keep the plane, a Boeing 737 Max 9, in service on Jan. 5 with some restrictions, carrying passengers until it completed three flights that were scheduled to end that night in Portland, Ore., the site of one of the airline’s maintenance facilities.

Before the plane could complete that scheduled sequence of flights and go in for the maintenance check, the door plug blew out at 16,000 feet, minutes after embarking on the second flight of the day, from Portland to Ontario International Airport in California.

The plane landed safely and no one was seriously injured, but the incident focused new attention on Boeing’s manufacturing processes and the safety procedures followed by airlines.

The scheduling of the maintenance check on the plane has not previously been reported. It demonstrates that the airline chose to keep the plane in service while it made its way toward the maintenance facility rather than flying it to Portland without passengers.

Alaska Airlines confirmed the sequence of events. But the airline said the warnings it had on the plane did not meet its standards for immediately taking it out of service.