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Federal investigators in the US have launched a probe into how a section of a new Boeing 737 Max blew out mid-flight, as airlines in Turkey and Panama grounded their planes for inspection.
The withdrawals come after the US airline regulator, the Federal Aviation Administration, on Saturday ordered the temporary grounding of some 737 Max 9s operated by US airlines or in US territory.
All 171 passengers and six crew of the Alaska Airlines-operated Boeing plane landed back safely at Portland, Oregon, after the incident on Friday night, but the outcome could have been much worse, according to investigators.
“We are very fortunate this didn’t end up in something more tragic,” Jennifer Homendy, the head of the National Transportation Safety Board, said at a press conference in Portland late on Saturday.
Boeing has called a company-wide safety meeting for Tuesday to discuss its response to the incident.
Chief executive David Calhoun, who will host the meeting from the Renton, Washington, factory where the Max is assembled, said the meeting would reinforce the company’s focus on safety.
“When serious accidents like this occur, it is critical for us . . . to understand and address the causes of the event, and to ensure they don’t happen again,” he said in a memo to employees on Sunday.
The accident happened at about 16,000 feet rather than at cruising altitude and only 10 minutes into the flight, the NTSB said. No one was in the two seats next to the deactivated exit cabin door that blew out, leaving a gaping hole in the fuselage of the plane.
While often used as an additional exit on more densely configured low-cost carriers, the door is permanently plugged on Alaska Airlines planes. Passengers seated on the inside see only a window.
Investigators on Sunday were looking for the missing blown-out door and plan to look at maintenance records, the pressurisation system and the door components.
The probe is focused on the Alaska Airlines incident rather than more broadly on Boeing’s Max fleet, Homendy added, while noting: “We’ll go where the investigation takes us.”
The “most astonishing thing to me is that the door came off”, said John Cox, a retired pilot and chief executive of Safety Operating Systems, an aviation safety consultancy in the US. Other types of aircraft similarly use plug-in doors, he noted, adding: “I don’t know of any case where this has occurred previously.”
With the aircraft being just two months old, investigators would look “in great detail at the assembly records and quality assurance inspections of that part of the aeroplane,” said Cox.
The accident is a blow to Boeing, which has struggled with manufacturing defects on the 737. It continues to experience the fallout from a 20-month worldwide grounding imposed by regulators after a pair of deadly crashes five months apart.
The US plane maker said in a statement on Saturday that it supported the temporary grounding.
“Safety is our top priority,” it said. “We agree with and fully support the FAA’s decision to require immediate inspections of 737-9 aeroplanes with the same configuration as the affected aeroplane.”
There are 215 Max 9 aircraft in service globally, according to data from aviation consultancy Cirium. The two biggest operators are United Airlines and Alaska Airlines in the US, Turkish Airlines and Copa Airlines of Panama.
Copa said it had temporarily suspended flights of 21 Boeing 737 Max 9 jets. Turkish said it had withdrawn its small fleet of five Max 9 aircraft.
Alaska Airlines cancelled 21 per cent of its flights on Sunday, while United cancelled 8 per cent, according to flight data website FlightAware. Copa and Aeroméxico reported cancellations of 14 and 11 per cent, respectively.
Garth Thompson, chair of the United Airlines unit of the Air Line Pilots Association, said that while the union was happy that regulators had acted cautiously, he had yet to hear of inspections finding a similar problem on another aircraft.
“This has been hopefully a one-off,” he said.
The European Union Aviation Safety Agency said it had adopted the FAA’s emergency directive but that this was a “precautionary measure as we understand from both the FAA and Boeing that no European airlines in EASA member states currently operate an aircraft in the affected configuration”.
Britain’s Civil Aviation Authority said on Saturday that as there were no UK-registered 737 Max-9 aircraft, “the impact on UK operated aircraft and consumers is minimal”. The agency said it had written to all non-UK and foreign permit carriers to “ask for confirmation that inspections have been undertaken prior to any operation into UK airspace”.