Source: Katu2.com
"PORTLAND, Ore. - The 24-minute eruption of steam and ash from Mount St. Helens prompted Alaska Airlines on Friday to diverted four planes on their way to Portland International Airport to Seattle.

"Our pilots are instructed and trained not to fly through those plumes and they will not do that," said airline spokesman Sam Sperry.

Federal officials contacted airline pilots heading toward Portland to let them know Mount St. Helens was belching steam and ash, the Federal Aviation Administration said.

It's up to pilots and the airlines they fly for to decide whether to reroute, said Mike Fergus, a Seattle-based spokesman for the FAA.

"There are no two ways about it, you don't want to be going through an ash plume," Fergus said.

The National Weather Service said it appears there was little ash in the plumes emitted by Mount St. Helens.

Steve Johnson, spokesman for the Port of Portland, which manages the airport, said he knew of no other airlines that diverted or canceled flights.

"The airport is open and fully operational," Johnson said. "We have given consideration over the past few days to operations in the event of a major eruption. But at this time there are no changes in operation."

The Portland airport is about 50 miles away from Mount St. Helens."