Alaska Airlines allowed the Boeing plane that had a mid-air blowout this week to fly despite warnings from a cabin pressurisation system.

The National Transportation Safety Board (NTSB), the United States’ chief accident investigator, said on Monday that warning lights were triggered on the brand-new Boeing 737 Max 9 on three flights. Two of the alarms came on consecutive days before the plane suffered a terrifying fuselage blowout on Friday.
The company stopped flying the aircraft over the Pacific Ocean to Hawaii due to the warnings, yet kept it flying over land, the NTSB said.

On Friday, a plug covering a spot left for an emergency door tore off the plane as it flew 4,800 metres (16,000 feet) above Oregon.

Jennifer Homendy, chair of the NTSB, said maintenance crews checked the plane and cleared it to fly, but the airline decided not to use it for the long route to Hawaii over water so that it “could return very quickly to an airport” if the warning light reappeared.

Friday’s flight was headed from Oregon to Southern California and made it back to Portland without serious injury to any of the 171 passengers and six crew members.