The US air safety regulator announced Saturday it was grounding and ordering inspections on some Boeing 737 MAX 9 airplanes a day after a window panel blew out of one of the aircraft over the state of Oregon. The Federal Aviation Administration “is requiring immediate inspections of certain Boeing 737 MAX 9 planes before they can return to flight,” the agency said in a post on X, formerly known as Twitter. The agency said a total of around 171 aircraft worldwide would be affected, with each inspection taking four to eight hours. “Safety will continue to drive our decision-making,” the FAA statement said. Alaska and United Airlines fly the largest number of MAX 9 planes. Boeing has so delivered some 218 737 MAX 9 planes, the company told AFP. On Friday, US-based Alaska Airlines had grounded all its 65 Boeing 737 MAX 9 planes after a flight with 177 people onboard was forced to make an emergency landing, with passengers saying a window panel blew out after takeoff. Alaska’s Flight 1282 had departed from Portland International Airport Friday evening. It returned safely around 20 minutes later after cabin crew reported a “pressurization issue,” according to the FAA. Images posted on social media showed the window panel of a plane blown out, with emergency oxygen masks hanging from the ceiling. “Following tonight’s event on Flight 1282, we have decided to take the precautionary step of temporarily grounding our fleet of 65 Boeing 737-9 aircraft,” Alaska Airlines CEO Ben Minicucci said in a statement Friday. “Each aircraft will be returned to service only after completion of full maintenance and safety inspections,” he said. Kyle Rinker, a passenger on the flight, told CNN that a window popped off soon after takeoff. “It was really abrupt. Just got to altitude, and the window/wall just popped off,” he told the broadcaster. Another passenger, Vi Nguyen, told The New York Times that a loud noise during the flight had woken her. “I open up my eyes and the first thing I see is the oxygen mask right in front of me,” Nguyen told the newspaper. “And I look to the left and the wall on the side of the plane is gone.” “The first thing I thought was, ‘I’m going to die,'” she added. – ‘Rare occurrence’ – The National Transportation Safety Board, FAA and Alaska Airlines each said they were investigating the incident. “While this type of occurrence is rare,” the airline said in an earlier statement, “our flight crew was trained and prepared to safely manage the situation.” The plane, which had been headed to Ontario, California, was certified airworthy in October and was newly delivered to Alaska Airlines, according to the FAA registry website. Boeing wrote on X that it was gathering more information and a technical team stood ready to support the investigation. Boeing has struggled in recent years with technical and quality control issues related to its 737 MAX models. In December, the US aviation giant told airlines that MAX aircraft should be inspected to check for loose hardware on plane rudder control systems after an international operator discovered a bolt with a missing nut while performing routine maintenance. Boeing’s 737 MAX planes were grounded worldwide following two MAX 8 crashes in 2018 and 2019 that killed 346 people in total. The FAA approved the planes’ return to service only after the company made changes to its flight control system.