How on this earth can you make a [presumably] 2+ hour film about GMC?
I'm afraid the title of the film is part of the overall joke! It's has nothing to do with GMC. Puzzlingly, it's called 'Jet' in the UK and 'Ground Control' in the USA. Both of which fail to describe the content.
It's a terrible film and I urge anyone to steer well clear.
See here 
For anyone who
has seen it. I found this review on IMDB which summed it up nicely for me.
Folks believe me, this movie has about as much to do with real air traffic controllers as Barney has to do with real dinosaurs. I mean really, if there was a total power failure in the control room you wouldn't see controllers just sitting around with their feet up waiting for Fonzie to come to the rescue! Obviously there was no ATC technical advisor on this film. And what's up with all the 'cute' phraseology between pilots and controllers? And it will be a very cold day in hell when an air traffic controller tells an air carrier captain how to fly his aircraft in an emergency. Absolutely incredible!
No one likes to see his profession shown in such a crummy light. And, by the way, I'm a non-retired, non-simulated, real life professional air traffic control specialist.
Source: IMDB.com