ALASKA AIRLINES HAS grounded all its Boeing 737-9 aircraft, hours after a window and a piece of fuselage on one plane blew out in mid-air, forcing an emergency landing in Oregon.

The incident occurred shortly after take-off from Portland and the gaping hole caused the cabin to depressurise.

Flight data showed the plane climbed to 16,000ft before returning to Portland International Airport. The airline said the plane landed safely with 174 passengers and six crew members.

“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 chief executive Ben Minicucci said in a statement.

The aircraft will be returned to service after full maintenance and safety inspections, which Minicucci said the airline expected to be completed within days.

Flight 1282 and our next steps with the Boeing MAX-9: https://t.co/LFxJvQYNcA pic.twitter.com/oemRokr1tz

— Alaska Airlines (@AlaskaAir) January 6, 2024

The plane was diverted about about six minutes after taking off, according to flight tracking data from the FlightAware website.

The pilot told Portland air traffic controllers the plane had an emergency, was depressurised and needed to return to the airport, according to a recording by the website LiveATC.net.

A passenger sent KATU-TV in Portland a photo showing the hole in the side of the plane next to passenger seats. Video shared with the station showed people wearing oxygen masks and passengers clapping as the plane landed.

The National Transportation Safety Board said it was investigating an event on the flight and would post updates when they are available. The Federal Aviation Administration also said it would investigate.

The Boeing 737-9 Max involved in the incident received its certification two months ago, according to online FAA records.

The plane had been on 145 flights since entering commercial service on November 11, said FlightRadar24, another tracking service. The flight from Portland was the aircraft’s third of the day.

Boeing said it was aware of the incident, working to gather more information and ready to support the investigation.

The Max is the newest version of Boeing’s 737, a twin-engine, single-aisle plane frequently used on US domestic flights. The plane went into service in May 2017.

NEW IMAGE from on board Alaska Airlines 1282 after ***part of the fuselage*** blew out mid-flight. Successful emergency return to Portland after 20 minutes in the air. 10-week-old (!) Boeing 737 Max 9. NTSB investigating. pic.twitter.com/qjX8fQ1br1

— Pete Muntean (@petemuntean) January 6, 2024

Two Max 8 jets crashed in 2018 and 2019, killing 346 people and leading to a near two-year worldwide grounding of all Max 8 and Max 9 planes. They returned to service only after Boeing made changes to an automated flight control system implicated in the crashes.

Last year, the FAA told pilots to limit use of an anti-ice system on the Max in dry conditions because of concern that inlets around the engines could overheat and break away, possibly striking the plane.

Max deliveries have been interrupted at times to fix manufacturing flaws. The company told airlines in December to inspect the planes for a possible loose bolt in the rudder-control system.