Alaska Airlines Flight 1282 was a scheduled domestic passenger flight operated by Alaska Airlines from Portland International Airport in Portland, Oregon, to Ontario International Airport in Ontario, California.

A preliminary report published on February 6 said that four bolts, intended to secure the door plug, had been missing when the accident occurred and that Boeing records showed evidence that the plug had been reinstalled with no bolts prior to the initial delivery of the aircraft.

[4] The MAX 9 has optional rear mid-cabin emergency exit doors, on each side of the aircraft behind the wings.

[4] From November 27 to December 7, the aircraft was under modification by AAR Corp at a facility in Oklahoma City to install a satellite antenna for in-flight internet service atop the rear fuselage, in the vicinity of the door plugs.

[26] At a media briefing on January 8, the NTSB provided the following timeline of key events obtained from the flight data recorder.

[6] The airline later said that 18 aircraft were ready to return to service on January 6 after determining that those 737 MAX 9s had already had their door plugs inspected "as part of a recent heavy maintenance visit".

[14] However, later in the day, on January 6, the Federal Aviation Administration (FAA) issued an Emergency Airworthiness Directive (EAD) that grounded all Boeing 737 MAX 9 aircraft with a mid-cabin door plug installed, pending a required inspection and corrective actions where required.

[28][29] Turkish Airlines of Turkey and Lion Air of Indonesia also grounded their fleets for inspection.

[30] On January 7, the European Union Aviation Safety Agency (EASA) adopted the FAA's EAD, though it stated that no airline in its jurisdiction currently operated any MAX 9 aircraft with the door plug configuration.

[31] The cabin door plug was discovered in the backyard of a home in the Cedar Mill area, near Oregon Route 217.

[41][42] Alaska Air Group reported in April 2024 that Boeing had paid about US$160 million as initial compensation to address the hit from the temporary grounding of 737 MAX 9 jets.

[43] The compensation package also included allowing Alaska to return the aircraft involved to Boeing, reducing storage and maintenance costs for the airline.

[44][45] Across all MAX 9 customers, Boeing agreed to pay a total of US$443 million to compensate them for losses during the grounding.

The FAA, Alaska Airlines, the Air Line Pilots Association (the union representing Alaska pilots), the Association of Flight Attendants (the union representing Alaska flight attendants), Boeing, Spirit AeroSystems, and the International Association of Machinists and Aerospace Workers (the union representing Boeing and Spirit AeroSystems workers) are providing support as members of the investigation party.

[23] However, due to the faults, Alaska Airlines had restricted the aircraft from operating extended overwater flights (under ETOPS rules) until a detailed maintenance inspection could occur.

[52] On January 8, United Airlines stated they had found loose bolts during inspections on an undisclosed number of grounded aircraft.

[53][54] On January 9, Boeing's president and CEO, Dave Calhoun acknowledged the company's mistake in a company-wide meeting on safety and transparency following this accident.

[57] Also on January 10, the FAA notified Boeing that it was under investigation for "alleged noncompliance" with regulations relating to new aircraft inspection and testing.

[24] Investigation on the status of the retention bolts designed to prevent the door plug from moving upwards is ongoing.

[needs update] These actions are separate from the FAA's investigation and the agency's plan to increase oversight of 737–9 production.

[60][61] On March 13, NTSB chairman Homendy stated in a letter to Congress that security footage of the aircraft's door plug installation back in September had been overwritten.