The Alaska Airlines Boeing 737 Max 9 that had an exit door blowout on Jan. 5 had been scheduled for a maintenance check that evening, according to a New York Times report.
The aircraft ultimately completed just one of its three scheduled flights on Jan. 5 before an exit door plug blew out while the plane was at 16,000 feet and ascending, moments after departing from Portland, Ore. No one died or was seriously hurt during the incident, but it has sparked intensified scrutiny of Boeing and its production processes as well as lawsuits against Boeing and Alaska.
In a post-incident audit, the FAA found "multiple instances" in which Boeing and its contractor Spirit AeroSystems allegedly fell short of quality-control requirements. The Justice Department has opened a criminal probe into the incident.
In a statement, Alaska Airlines said, "We remain confident in our maintenance and safety actions leading up to the incident. We look forward to continuing our participation in a robust investigation led by the NTSB to ensure something like this never happens again."
Early in the investigation of the incident, NTSB chairwoman Jennifer Homendy revealed that Alaska Airlines had placed restrictions on flying the plane involved in the Jan. 5 incident on lengthy overwater routes, such as to Hawaii, because a pressurization warning light had illuminated on Dec. 7 and then again on Jan. 3 and Jan. 4.
In a detailed story published Tuesday, the New York Times elaborated on that information, reporting that concerns about the door prompted Alaska engineers and technicians on Jan. 4 to schedule the maintenance check for the following day for Portland. But Alaska opted to operate the plane on passenger flights during the interceding day.
Speaking to the Times, Donald Wright, Alaska's vice president for maintenance and engineering, said that the pressurization light had come on twice in the previous 10 days, short of the three times that that would have triggered the airline to take more aggressive action.
Max Tidwell, Alaska's vice president for safety and security, also stood by the decision.
"From my perspective as the safety guy, looking at all the data, all the leading indicators, there was nothing that would drive me to make a different decision," he told the Times.
The exit door plug was found in a suburban Portland backyard missing four bolts designed to hold it in place. The NTSB has concluded that bolts on the door plug likely were not reinstalled after being removed last September for repair work at the Boeing plant in Renton, Wash.