I was a kid and I was watching a movie on TV around 2005 I think, but I could be wrong.

It was in English and in color.

What I remember of the plot is these teens(or young adults) are in this really gorgeous rocky world that they discovered(possibly). At least one of the boy characters gets inducted into this academy where they are learning to be some sort of flying soldier. They have to learn to fly on the back of these dinosaur bird things. They have some sort of simulated flight training with a saddle that gets elevated and flung around in this dark grey room. The final step is a test where they have to go and call it by holding up their hand on a cliff side and one bird thing chooses whether or not to answer the call.   I think the other characters all get split up and have their own sort of test adventures, but I don’t really remember what those were.

Can anyone help me? Sorry this is so vague, I was young.