The Federal Aviation Administration on Saturday ordered airlines to ground more than 170 Boeing 737 Max 9 aircraft for inspections, a day after after a panel blew out in the middle of an Alaska Airlines flight.
The emergency airworthiness directive will affect about 171 planes worldwide and applies to U.S. airlines and carriers operating in U.S. territory.
United has about 80 Boeing 737 Max 9 aircraft, though some of them recently underwent routine inspections.
Alaska Air said it would ground its fleet of more than 60 Boeing Max 9 aircraft.
Alaska Airlines Flight 1282 was bound for Ontario, California when it returned to Portland, Oregon shortly after takeoff on Friday after a pressurization issue was detected.
No serious injuries were reported on the flight, according to federal safety officials.
