AIRPORT '77 is pretty low on the Believability Scale, but it's still fun for a one time watch. I especially like the scenes with Jack Lemmon being a action star. It was pretty cool seeing him running around, tumbling, swimming and barking orders at people. And of course Olivia and Jimmy are always great. George Kennedy returns, but he really doesn't do very much.
Word around the campfire is there was a much longer version shown of television back in the day, but I've never seen it and it looks to be mostly just filler.
Part 1 - Airport
Part 2 - Airport 1975
Part 4 - Concorde...Airport '79
Look at the size of that laserdisc player!!!
Inspiration for the cake scene in the "November Rain" video?