Boeing stock tumbles after door panel blows out on Alaska Airlines flight

Alaska Air Group shares also dip as US regulators order dozens of Boeing 737 Max 9 planes to be grounded

A hole where the door panel was torn off during an Alaska Airlines flight. AP Photo

Boeing shares plunged during trading on Monday after a panel on a 737 Max 9 plane blew out last week, forcing dozens of the jets to be grounded.

The emergency incident happened on January 5 while an Alaska Airlines plane was flying at about 4,800 metres, six minutes after taking off from Portland, Oregon, bound for Ontario, east of Los Angeles.

Boeing shares were down more than 8 per cent at the end of the trading day.

Shares in Alaska Air Group were almost fully recovered after they plunged by more than 4 per cent when Wall Street opened.

Video from the National Transportation Security Board showed a hole where the door panel had dislodged.

It was found on Sunday near Portland, the NTSB said.

NTSB chairwoman Jennifer Homendy said the plane was not being used for long-haul flights to Hawaii because a warning light indicating a potential pressure problem went off during previous flights.

Ms Homendy painted a harrowing picture of Friday's accident during her briefing.

She said a rush of air blew through the aircraft after the panel broke off, damaging several seats and ripping off the insulation from the plane's walls.

The co-pilot's headset was forced off and the captain also lost part of hers, Ms Homendy said.

None of the passengers or crew members were injured and the plane returned to Portland. No one was sitting next to the door plug.

The Federal Aviation Administration has ordered airlines to ground 171 Boeing 737 Max 9 aircraft that have the panel installed.

All 65 of Alaska Airlines' Boeing 737 Max 9 planes have been grounded and 60 flights were cancelled on Monday after the order.

Boeing has provided instructions on how airlines can inspect the company's 737 Max 9 aircraft, US media reported.

Boeing previously said it supported the FAA's decision to require immediate safety checks and that it would support the NTSB's investigation.

United Airlines, which also operates the plane, has grounded all of its Boeing 737 Max 9 aircraft to conduct safety inspections.