@ italia458: Thank you a thousand times. This is an issue that has been bothering me since my PPL lessons. I just accepted everything, because nobody I've met so far was able to give me a clear answer. You just did, and you made my day !
@ ATCast and keith williams: Also a big thanks for your explanations !
With those clear explanations, it all sounds so simpel and logically. I don't know why I never figured out the correct explanation. I guess I combined different source materials the wrong way.
Thanks again !!!