Boeing jetliner that suffered inflight blowout was restricted

PORTLAND, Ore. — The Boeing jetliner that suffered an inflight blowout over Oregon was not being used for flights to Hawaii after a warning light that could have indicated a pressurization problem lit up on three different flights.

Alaska Airlines decided to restrict the aircraft from long flights over water so the plane “could return very quickly to an airport” if the warning light reappeared, Jennifer Homendy, chair of the National Transportation Safety Board, said Sunday.

Homendy cautioned that the pressurization light might be unrelated to Friday's incident in which a plug covering an unused exit door blew off the Boeing 737 Max 9 as it cruised about three miles (4.8 kilometers) over Oregon.

On Monday, the Federal Aviation Administration approved guidelines for inspecting the door plugs on other Max 9 jets and repairing them, if necessary. That move should speed the return to service of 171 planes that the FAA grounded under an emergency order Saturday.

Alaska has 64 other Max 9s, and United Airlines owns 79 of them. No other U.S. airlines operate that model of the Boeing 737.

Shares of The Boeing Co. and Spirit AeroSystems, which builds the fuselage for Boeing's 737 Max, both tumbled 7% at midday Monday, the first day of trading since the incident occurred. Shares of Alaska Airlines were nearly unchanged after slumping earlier in the session.

The auto-pressurization system warning on the ill-fated Alaska Airlines jet lit up during three previous flights. Homendy said she didn't have details about a Dec. 7 incident, but that it came on again during a flight on Jan. 3 and after the plane landed on Jan. 4 — the day before the blowout.

“We plan to look at that more and we've requested documentation on all defects since delivery of the aircraft on Oct. 31," she said.

The NTSB said the lost door plug was found Sunday near Portland, Oregon, in a the backyard of a home. Investigators will examine the plug, which is 26 by 48 inches (66 by 121 centimeters) and weighs 63 pounds (28.5 kilograms), for signs of how it broke free.

Investigators will not have the benefit of hearing what was going on in the cockpit during the flight. The cockpit voice recorder — one of two so-called black boxes — recorded over the flight's sounds after two hours, Homendy said.

At a news conference Sunday night, Homendy provided new details about the chaotic scene that unfolded on the plane. The explosive rush of air damaged several rows of seats and pulled insulation from the walls. The cockpit door flew open and banged into a lavatory door.

The force ripped the headset off the co-pilot and the captain lost part of her headset. A quick reference checklist kept within easy reach of the pilots flew out of the open cockpit, Homendy said.

Two cell phones that appeared to have belonged to passengers on Friday's terrifying flight were found on the ground. One was discovered in a yard, the other on the side of a road. Both were turned over to the NTSB.

The plane made it back to Portland, however, and none of the 171 passengers and six crew members was seriously injured.