Alaska Airlines flight returns after masks deploy

PORTLAND, Ore. – An Alaska Airlines flight returned to Portland International Airport Tuesday morning after the cabin's oxygen masks dropped 15 minutes into a flight to Denver.

There were no injuries and the 69 passengers were placed on other flights to Colorado, said Amanda Tobin, an Alaska Airlines spokeswoman.

"As a precaution, we're checking into why the oxygen masks deployed and we're also trying to determine whether there was a problem with the cabin pressure," Tobin said.

Alaska Airlines has had three similar problems in the last two months. The incidents involved three different types of aircraft and Tobin said the problems don't appear to be connected.

On Saturday, a flight bound for Seattle had to turn around and make an emergency landing at Washington Dulles International Airport after the aircraft did not pressurize properly. Tobin said a door on the Boeing 737-700 was not fully latched.

On Valentine's Day, a jet bound for Denver returned to Seattle because of a pressurization problem. Five passengers were treated for ear and sinus pain.

The Boeing 737-400, the same type of plane involved in Tuesday's incident, turned around after a warning alarm sounded in the cockpit, indicating a malfunction in the plane's automatic pressurization system, the airline said.

No masks dropped, and the pilot activated a backup manual pressurization system for the return to Seattle.

On Dec. 26, an Alaska Airlines jet made an emergency descent after a hole in the fuselage caused the Boeing MD-80 to lose cabin pressure.

A ramp worker acknowledged failing to immediately report striking the plane with a baggage cart or baggage-belt machine, the National Transportation Safety Board said.

The bump created a crease in the plane's aluminum skin, which opened into a gash as the plane came under increased pressure at 26,000 feet.