NTSB Finds Missing 737 Max 9 Door Plug in Teacher’s Backyard

The loss of the door plug resulted in what has been described as "explosive decompression.”

During a media update Sunday, Homendy noted that the teacher took photographs of the refrigerator-sized door and contacted the agency via witness@NTSB.gov.

Homendy described the door plug as a "yellowish green on one side, which might make it blend into the vegetation, and white on the other, measuring 26 by 43 inches and weighing 63 pounds."

The NTSB chief called the door plug a crucial piece of evidence in the investigation into what caused the incident aboard Alaska Airlines Flight 1282. The aircraft took off from Portland International Airport (KPDX) just before 5 p.m. PST on Friday, then as the aircraft climbed through 16,000 feet en route to Ontario, California, the door plug blew off the aircraft, triggering explosive decompression.

The door plugs are located in row 26 of the aircraft. The seats adjacent to the left side door plug were not occupied at the time. Homendy noted the force of the decompression damaged seats and sucked loose items, such as cellphones, out of the aircraft. No serious injuries were reported to the 177 persons on board.

During the media update, Homendy stressed that the part that departed the aircraft was a door plug and not a door, because it is not usable for entry and egress of the aircraft. The right-side door plug, which is still on the aircraft, is undergoing a detailed inspection on Monday.

The agency is working with Boeing to obtain technical information about the door plug and shared a description of the part, stating it has two hinges on the bottom that allow it to open for inspection about 15 degrees. In addition, the door plug has "12 stop fittings, six on each side, which are essentially circles on the door plug that line up with circles on the airliner. The purpose of these stop fittings is to prevent the door plug from being pushed out of the airframe."

According to Homendy, the NTSB’s structures team spent the weekend studying damage to the aircraft and what are called “witness marks” on the airframe and identifying components that will be sent back to the agency structures lab for analysis. The components will be inspected under a microscope to look for paint marks, fractures, deformation, and evidence of shearing.

The aircraft systems are also under scrutiny, as the team noted the auto pressurization light illuminated on flights on December 7, January 3, and January 4. The flight crew followed procedure, activating the backup and reporting the issue to the airline's maintenance staff. It was checked out by maintenance, and the aircraft returned to service with restriction that it not be flown to Hawaii as a precaution.

Homendy said the airline had ordered an additional maintenance inspection of the light, but it was not completed before the decompression flight.

The NTSB has requested documentation of "all defects of the aircraft since its delivery on October 31 of 2023."

According to the NTSB, there was no external damage to the aircraft. However, there was on the interior, including torn parts of plastic trim and insulation and damaged interior plastic windows—none of which is considered structural in nature. Damage was reported in rows 33, 32, 31, 27, 26, 25, 12, 11, 4, 3, 2, and 1.

The door plugs are located in row 26 on the 737 Max 9. The headrests from seats 26A and 25A were torn, the seats were "torqued," and the seat back and tray table of 26A are missing. Homendy noted seats 26A and 26B were not occupied during the flight, adding, "We have 178 seats on this plane, 171 had passengers in them."

The oxygen masks were deployed as a result of the decompression. Homendy said the tubing for oxygen masks in 26A and 26B were found sheared off.

There were three infants aboard the flight being held in the laps of their caregivers. They were not harmed, but Homendy noted that while the FAA permits children under the age of 2 to be held on the lap of an adult during flight, the NTSB, FAA, and Alaska Airlines recommend that caregivers carry their children in car seats, purchasing a seat for the infant and strapping them in just as they would in an automobile.

Four unaccompanied minors also were on the flight. Homendy said that when the incident happened, the flight attendants were very focused on making sure the minors had their lap belts and oxygen masks on and praised them for their actions during the emergency. Homendy said the NTSB is gathering information from the flight attendants as part of the investigation.

According to Homendy, the flight crew reported hearing a loud bang, and the flight deck door sprung open. The copilot "jolted forward, losing her headset, and the captain lost part of his." They immediately put on their oxygen masks. The quick reference, laminated checklists that were in front of both pilots were sucked out of the aircraft, so the captain grabbed the quick reference handbook kept in a pocket on the flight deck and handed it to the first officer.

The flight deck door slammed against the lavatory door, and was pinned there, but there was no one inside. It took a flight attendant three tries to get the flight deck door closed. Communication between the flight deck and cabin was very difficult because of the noise.

The cockpit voice recorder (CVR) and flight data recorder (FDR) were sent to the NTSB lab on Sunday. The information on the FDR is helping the agency narrow the search area for evidence.

Businesses and homeowners in the area have been asked to check their roofs for parts of the aircraft or other items that may have been ejected from the jet. Two cellphones were found along a road in the vicinity of the door plug.

Homendy noted that citizens in the area were using drones to search for evidence, and she asked that homeowners and businesses with security cameras to check for any video of the event, which happened at 5:11 p.m. PST on Friday.

"If you see something, please report it to us, [at] witness@ntsb.gov, or please call local authorities," Homendy said.

Homendy said the investigation may be hampered somewhat because the CVR would be no help.

"[It was] completely overwritten,” she said. “There is nothing on the cockpit voice recorder. …There was a lot going on the flight deck, and on the airplane it was a very chaotic event. The circuit breaker for the CVR was not pulled. The maintenance team went out to get it, but it was at the two-hour mark, and it was completely overwritten—at two hours, it rerecords over it."

She noted that since 2018 the NTSB has done four investigations where the CVRs were overwritten, among them a situation in San Francisco when an Air Canada flight came within 60 feet of landing on a taxiway where four other aircraft, carrying a total of 1,000 people, were holding. The Air Canada flight executed a go-around.

Homendy said the NTSB is appealing to the FAA to increase the time on CVRs from two hours to 25, "which is consistent with Europe and many other countries." She added that the time used to be 30 minutes before overwriting took place.

The FAA has released a Notice of Proposed Rulemaking (NPRM) to extend the CVR overwrite time on newly manufactured aircraft but not on aircraft already in use. Homendy suggested the FAA adjust the NPRM to include retrofitting of aircraft already in service, pointing out that airliners often have a lifespan of 40 years or more.

"I am calling on the FAA to change the rulemaking for 25-hour CVRs, not just new but retrofitting aircraft,” she said. “If the FAA won't do it, we hope Congress will in the FAA authorization bill to ensure that it does happen."

Homendy added that the NTSB may be on the Portland scene for weeks.

Alaska Airlines immediately grounded all of its 737 Max 9s  following the incident.

A few hours later, the FAA grounded all 737 Max 9 aircraft, mandating they be inspected immediately. As a result, there have been hundreds of flight cancellations for airlines that fly the 737 Max 9, among them Alaska and United.

Spirit AeroSystems, the Wichita, Kansas, manufacturer of the Boeing 737 Max jets, is assisting in the investigation. Boeing also has a technical team supporting the NTSB probe.