I could of sworn that it was Mount Spurr but it was Mt. Redoubt. At least that is what the Boeing Ash Avoidance video, I have says. They use a video of the ash plume of that eruption to demonstrate that ash plums often look like water clouds and show how Alaska Airlines where able to continue operations during the eruption. I lived about 50 miles south of the mountain during that eruption and got ashed too. It was a KLM 747-400 and my understanding is that it had just recently been delivered from Everett. If you where good with using micro-mesh you would have had been very busy. Every one of the side passengers windows had to be repolished. KLM didn't want to spend the $4000 dollars for each window to replace.
There are four major volcanos that line the west side of Cook Inlet. Augustine Volocano is the southernmost then Mt. Redoubt, Mt. Illiamna and Mt. Spurr. The only one that hasn't erupted in the past 15 years is Mt. Illiamna. Mt Spurr was the last eruption and that was in 1992/3. (I missed that one.)
Provided the direction of the wind is known and the airport isn't directly downwind most airports can continue normal operations. When I was working at Cold Bay. Alaska we where with in Forty Five miles of four volcanos, Mt. Pavloff (37 miles), Mt. Dutton(35 miles), Mt. Shishaldan(43) and Roundtop Volcano(47). Mt Pavloff during the summer and winter of 1996 was in a constant state of eruption. The airport I worked at was uneffected by this eruption.
If you want more info about Alaskan Volcanos (Not flying around them. Sorry.) then you may want to visit this address The Alaska Volcano Observatory">
OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.