The 4th Airport is Airport '77. The one where they end up at the bottom of the ocean. That movie scares the daylights out of me!!!!! It's so cheesy, but the concept is terrifying.
Pierce Brosnan made a volcano disaster movie a few years back, but I have forgetten the name. It's right on the tip of my tongue, but I just can't get it. I'm sure someone here can help me remember.
Erika