It seems a little bit like a small movie despite some big sets. Seems much smaller than 'Airport'.
This movie is somewhat about a Vietnam War vet and therefore I appropriately point out that Ken Burns ( himself!) pointed out that Ho Chi Minh was a brutal mass-murderer of landlords in the 1950s. In a land reform in North Vietnam! Now imagine this film if they could have pointed that out to the mad vet hijacker ( minus the 21st century part about Ken Burns!).
Ross Elliott is one of the passengers in this. He is almost totally non-noteworthy as one of them. Why him? Was he a friend or relative of the casting director's? Mr. Elliott was on The Twilight Zone in the ep 'Death Ship' ( see my comments) so linking this film up to TZ was very important. A film needs all the original TZ actors it can get. However, he would have much better suited to being, say, an air traffic controller than a passenger! So again-- why him as a passenger?
The incredible Charlton Heston and the ultra-beautiful Yvette Minieux are both prominently featured in this and are the best things to watch.