vegas jonny:
As Area controllers, we get used to the general principle that, all things being equal, jets tend to descend at a mach no until the IAS becomes the governing principle, and then they will descend at around 300kts until other speed restrictions take effect. There are variations within that (RYR 737-800s which have not been de-iced seem to hurtle around at 320 kts+!) but that is what we assume. If you vary that by a lot, while you do not have to tell us, the assumptions we make concerning your position relative to other traffic might prove awry and the point of the first post was to highlight this to you.
From your side, I squirm with embarrassment when I hear some of my colleagues asking traffic at FL300+ its IAS and then restricting it to that relatively low figure (260kts-) all the way down, along with everybody else behind. It shows a singular lack of appreciation of aircraft performance.
Regrettably, however, that is the way things are going these days. To keep costs down we are only training to the minimum standard, and peripheral knowledge is seen as unnecessary. How many times do you see questions posted on PPrune asking: "What is the answer to this question from the ATPL question bank?"? Rather than "Who can help me understand this subject?".
