On January 5, after departing from Portland, USA, Alaska Airlines’ California-bound Flight AS-1282 suffered an “explosive decompression” as a ‘plugged’ door of the Boeing 737 MAX-9 aircraft blew out. The flight had passed through 16,000 ft during its climb when the incident took place in the pressurised cabin. With 171 passengers and six crew members, the aircraft returned to Portland safely with reports of minor injuries to some passengers. What likely happened on the Alaska Airlines flight? Reports quoting National Transportation Safety Board (NTSB) Chair Jennifer Homendy, who spoke at a news conference on Sunday, said the NTSB will look at how the door was fastened and if there were related failures. The extremely quick loss of pressure from a sealed body, such as a flight, is known as explosive decompression. Pilots had received alerts on air pressurisation issues thrice between Dec 7 and Jan 4. The airline had then prohibited long flights over water “so it could return quickly to an airport” if required, until the issue was inspected thoroughly, media reports said. What exactly is a plugged door? Depending on an aircraft’s passenger-carrying capacity, airlines can either opt for additional emergency exits to meet regulations for evacuation or — if regulations do not require an extra emergency exit — opt for a ‘plugged’ door, as was the case with Alaska’s MAX-9. According to Reuters, "Boeing's largest single-aisle model in production has a panel known as a door plug to replace an exit that would be installed on planes configured to carry more passengers." Diagram of a Boeing 737-9 mid-cabin door plug and components (Source: Boeing) pic.twitter.com/7qPF5MGAOX — NTSB Newsroom (@NTSB_Newsroom) January 8, 2024 Under regulations, 737s which carry 190 or more passengers require extra emergency exits, according to media reports. But the affected MAX-9 had a seating capacity of 178 passengers. That’s why it had a ‘plugged’ door instead of an extra emergency exit. According to Reuters, the 737 MAX-9 can carry up to 220 people. If carriers install the maximum number of seats, the extra door is required to meet evacuation rules. Other cases of ‘explosions’ More deadly instances of such “explosive decompression” have been reported in the past. In ‘Aloft’, a collection of aviation writings, author, journalist and pilot William Langewiesche writes that aircraft accidents can be categorised into three types for simplicity. The most common ones are ‘procedural’, he says. The second type could be called ‘engineered’ — flaws engineers or test pilots failed to catch but, over time, are understood and solved. The third type, he says, is ‘system accidents’. In 2024, one might think that accidents like American Airlines Flight 96 (where an aircraft suffered an inflight structural failure), American Airlines Flight 191 (in which the left engine detached from the wing) or Aloha Airlines Flight 243 (in which a giant piece of the plane’s passenger cabin roof and walls cracked and blew off at 24,000 ft) don’t happen any longer. One might think that such accidents have been ‘engineered out’ by aircraft manufacturers and designers, but that has not been the case. Here’s a look at major instances: American Airlines Flight 96 On June 12, 1972, American Airlines Flight 96 took off from Los Angeles and was bound for New York with stops at Detroit and Buffalo. The aircraft was a DC-10, a widebody, trijet with one engine mounted in the tailfin, and it had entered service just the previous year. In the cockpit were Captain Bryce McCormick, First Officer R Paige Whitney and Flight Engineer Clayton Burke. About five minutes after taking off from Detroit, at 11,750 ft, the crew heard a loud “explosion”. It came from the aircraft’s rear. Before they could realise what was happening, a ‘hurricane’ rushed through the cockpit and cabin, blowing things away, knocking and blinding the crew and passengers. Flight 96 had suffered an explosive decompression. The DC-10’s aft (rear) cargo door had blown open midair. It sheared off the aircraft, leaving a gaping hole in the fuselage and allowing pressurised cabin air to escape at enormous speed, knocking the crew and passengers and even exposing them to the risk of being sucked out. No casualties were reported. The Windsor Incident The explosive decompression on Flight 96, also known as the ‘Windsor Incident’ as it took place over Windsor, Ontario, caused the cabin floor to collapse. As the cargo door came loose and blew away, it damaged the DC-10’s left tailplane. Control cables and wiring that ran under the cabin floor were severely damaged. The ceiling panels came loose. Stewardess Sandra McConnell barely escaped being sucked out, bolting herself in the lavatory behind her. There was chaos and fear in the cabin. Luckily, no one was ejected from Flight 96. Later, investigators blamed the cargo door issue on a design flaw. An electric motor that drove an actuator, latches and locking pin mechanism secured the door. But ground staff were facing problems in locking the door. It was a known problem. Other airlines operating the DC-10 were also facing the issue. McDonnel-Douglas, the manufacturer, was aware of it and had been working on a fix. As investigators later found out, the door appeared locked but was not. Turkish Airlines Flight 981 Just two years after the ‘Windsor Incident’, on March 3, 1974, Turkish Airlines Flight 981 took off from Istanbul for London with a stop in Paris. Shortly after taking off from Paris, the aircraft, also a DC-10, suffered an explosive decompression. As in Flight 96, a cargo door was not properly locked and came loose midair, plunging the jet into a forest in France, killing all 346 people on board. Flight 981 was not as lucky as Flight 96. American Airlines Flight 191 This too involved a DC-10. The crash occurred on May 25, 1979. Flight 191 was bound for Los Angeles from Chicago. As the DC-10 sped down the runway for takeoff, the left-wing engine separated from the aircraft, ripping a part of the wing and severely damaging hydraulic lines. Captain Walter Lux and First Officer James Dillard struggled with an uncontrollable aircraft, which climbed to only 325 ft before crashing into a building just outside the airport. The dramatic photograph of the stricken aircraft flying sideways just beyond the airport was taken by Michael Laughlin, then 24 years old, a student pilot. All 273 people on board (258 passengers and 13 crew members) and two persons on the ground were killed. Investigators blamed the engine separation on a mounting pylon failure. Aloha Airlines Flight 243 On April 28, 1988, Flight 243 took off from Hilo bound for Honolulu in Hawaii. There were 90 passengers and five crew members on board. At 24,000 ft, the Boeing 737 suffered an explosive decompression, which ripped off the passenger cabin’s roof and right and left walls from rows 1 to 6. A giant piece of the aircraft’s metal skin was cut like a cloth and removed at 24,000 ft to the horror of the passengers, who were now out in the open, lashed by cold winds, hanging on to the aircraft only by their seatbelts. Flight Attendant Clarabelle Lansing was sucked out, her body never to be found. She was the only fatality on the flight as Captain Robert Schornstheimer and First Officer Madeline "Mimi" Tompkins were able to land the plane safely at Maui.
