Now here's something I was never really sure about. You're flying at, say, FL350 and are given the following clearance:
"Descend pilot's discretion to FL240"
Obviously, the pilot chooses when he wants to start to descend, the question is: is the pilot required to let ATC know when he starts the descent? Or can he start the descent without saying anything? I would think that the pilot would have to let ATC know; I'm just wondering if that's right or not. Thanks!