Alaska Airlines timeline: How incident involving missing door plug unfolded

The defective door plug on an Alaska Airlines plane that forced an emergency landing as a door-sized hole opened up in the plane mid-flight is just the latest dangerous incident to occur with this type of aircraft.

The Boeing 737 Max has been under public scrutiny for several years following multiple crashes and malfunctions.

The occurrences include a Lion Air Flight 610 that killed 189 people when it crashed in Indonesia in October 2018 and Ethiopian Airlines Flight 302 that killed 157 people when it crashed in waters northeast of Jakarta -- both Boeing 737 Max 8 planes, a previous version of the aircraft.

Black box data from the Lion Air jet revealed the pilots struggled to fight the plane's malfunctioning safety system from takeoff to the moment it nose-dived into the Java Sea. A report by Indonesia's National Transportation Safety Committee found that there were detrimental problems with the left angle of attack (AOA) sensor.

Following the Ethiopian Airlines crash, the entire fleet was grounded worldwide for more than 600 days. The 737 Max started flying again in January 2023.

The door plug for the fuselage of a Boeing 737 Max 9 fell off during a flight's ascent on Friday, depressurizing the cabin and exposing passengers to open air thousands of feet above ground.

In statements released since Friday, Boeing has said it is aware of the incident and fully supports the FAA's decision to require immediate inspections of certain 737 Max 9 planes.

Here is how the most recent incident unfolded:

Friday, Jan. 5

5:07 p.m.: Alaska Airlines Flight 1282 takes off from Portland International Airport for Ontario, California, with 171 passengers and six crew members on board.

A few minutes after takeoff, as the plane reaches an altitude of 16,000 feet above sea level, a hole opens up next to seat 26A, prompting the pilot to declare an emergency.

Flight 1282 then initiates an emergency landing at Portland Airport. During the descent, terrified passengers captured footage showing the hole where the door plug came loose from.

The Boeing 737 MAX 9 plane has only been in operation since October 2023, FAA records show.

5:26 p.m.: Flight 1282 lands, less than 20 minutes after taking off.

5:34 p.m.: The plane arrives at the gate. Flight attendants instruct those who are injured to remain seated, and firefighters board the plane.

7:47 p.m. The NTSB posted on X, formerly known as Twitter, that it has started investigating the incident.

Saturday, Jan. 6

Midnight: Alaska Airlines temporarily grounds its Boeing 737 Max 9 fleet, totaling 65 planes, stating the aircraft will return to service "only after completion of full maintenance and safety inspections."

9 a.m.: Alaska Airlines returns the 737-9 aircraft to service after inspections on more than a quarter of its 737 Max 9 fleet is complete "with no concerning findings."

11 a.m.: United Airlines temporarily suspends service on select Boeing 737 Max 9 aircraft to conduct an inspection required by the FAA, it announces. The airline has 79 of the aircraft in operation.

3 p.m.: Alaska Airlines removes 18 planes from service until details about possible additional maintenance work are confirmed with the FAA, the airline announces.

4 p.m.: The FAA issues an emergency airworthiness directive, temporarily grounding certain Boeing 737 MAX 9's while operators conduct specific inspections before returning the aircraft to service -- more than 170 planes worldwide.

6 p.m.: All of the passengers who sustained injuries aboard Flight 1282 are medically cleared, according to Alaskan Airlines.

7 p.m.: United temporarily suspends service on all 79 of its Boeing 737 Max 9 planes, the airline announces.

8 p.m.: During a press conference, the NTSB announced that no one was sitting in 26A or 26B -- the two seats closest to the door -- when the door plug fell out. The search for the door plug continues.

Sunday, Jan. 7

6:30 a.m.: Nearly 700 flights are canceled nationwide due to the Boeing 737 Max 9 groundings, according to data from FlightAware.

11:30 a.m.: "Affected" planes will remain grounded until the FAA determines they are safe, the FAA said in a statement. Turkish Airlines, Copa Airlines and Aeroméxico all temporarily suspend service on their 737 Max 9s while doing inspections.

3:30 p.m.: A man finds a cellphone from a passenger on board Flight 1282 while on a walk in Portland.

9 p.m.: During a press conference, the NTSB announces that the door plug that fell out the fuselage has been found in a backyard in Portland.

Monday, Jan. 8

6:30 a.m.: Shares of Boeing Co. tumble 9% at the opening bell of the New York Stock Exchange as the Boeing Max 9 remains grounded.

4 p.m.: United announces it has found loose bolts during its inspection of its 737 Max 9 fleet. The airline did not disclose how many planes the malfunction was found on.

Tuesday, Jan. 9

2 p.m.: The FAA announces that every Boeing 737 Max 9 with a plug door will remain grounded until the administration determines that each can safely return to operation.

To begin this process, Boeing must provide instructions to operators for inspections and maintenance, the FAA said. Boeing offered an initial version of instructions on Monday, but it is now revising because of feedback received in response, according to the FAA

ABC News' Clara McMichael, Amanda Maile and Sam Sweeney contributed to this report.