The National Transportation Safety Board on Tuesday will be focused on preventing another terrifying event like the one involving a panel that flew off a Boeing 737 Max midair in January of 2024.

The board will discuss what NTSB investigators have uncovered over the past 17 months, including their revelation that bolts securing what is known as the door plug panel were removed and never replaced during a repair. Board members were also expected to approve recommendations to keep something similar from ever happening again.

The blow out aboard Alaska Airlines flight 1282 occurred minutes after it took off from Portland, Oregon, and created a roaring air vacuum that sucked objects out of the cabin and scattered them on the ground below along with debris from the fuselage. Seven passengers and one flight attended received minor injuries, but no one was killed. Pilots were able to land the plane safely back at the airport.

Oxygen masks dropped and phones went flying

The accident occurred as the plane flew at 16,000 feet (4,800 meters). Oxygen masks dropped during the rapid decompression and a few cellphones and other objects were swept through the hole in the plane as 171 passengers contended with wind and roaring noise.

The first six minutes of the flight to Southern California’s Ontario International Airport were routine. The Boeing 737 Max 9 was about halfway to its cruising altitude and traveling at more than 400 mph (640 kph) when passengers described a loud “boom” and wind so strong it ripped the shirt off someone’s back.

“We knew something was wrong,” Kelly Bartlett told The Associated Press in the days following the flight. “We didn’t know what. We didn’t know how serious. We didn’t know if it meant we were going to crash.”

The 2-foot-by-4-foot (61-centimeter-by-122-centimeter) piece of fuselage covering an unoperational emergency exit behind the left wing had blown out. Only seven seats on the flight were unoccupied, including the two seats closest to the opening.

Missing bolts put the focus on Boeing’s manufacturing

The panel that blew off was made and installed by a supplier, Spirit AeroSystems. It was removed at a Boeing factory so workers could repair damaged rivets, but bolts that help secure the door plug weren’t replaced. It’s not clear who removed the panel.

The NTSB said in a preliminary report that four bolts were not replaced after a repair job in a Boeing factory, but the company has said the work was not documented.

Boeing factory workers told NTSB investigators that they felt pressured to work too fast and were asked to perform jobs that they weren’t qualified for, including opening and closing the door plug on the particular plane involved.

A Boeing door installer said he was never told to take any shortcuts, but everyone faced pressure to keep the assembly line moving.

“That’s how mistakes are made. People try to work too fast,” he told investigators. The installer and other workers were not named in documents about the probe.

Problems with the Boeing 737 Max

The Max version of Boeing’s bestselling 737 airplane has been the source of persistent troubles for the company since two of the jets crashed, one in Indonesia in 2018 and another in Ethiopia in 2019, killing a combined 346 people.

Investigators determined those crashes were caused by a system that relied on a sensor providing faulty readings to push the nose down, leaving pilots unable to regain control. After the second crash, Max jets were grounded worldwide until the company redesigned the system.

Last month, the Justice Department reached a deal allowing Boeing to avoid criminal prosecution for allegedly misleading U.S. regulators about the Max before the two crashes.

But regulators at the Federal Aviation Administration have capped Boeing’s 737 Max production at 38 jets per month while investigators ensure the company has strengthened its safety practices.

Boeing hired a new CEO, Kelly Ortberg, last year and created a new position for a senior vice president of quality to help improve its manufacturing.

The company was back in the news earlier this month when a 787 flown by Air India crashed shortly after takeoff and killed at least 270 people. Investigators have not determined what caused that crash, but so far they have not found any flaws with the model, which has a strong safety record.