Mister Geezer,
Interesting what you say about having to maintain the last speed given until 4d if we are not told otherwise. Where is this written? I have never heard of it before (I'm not saying it isn't true but just that it's news to me). I can say this though - if I am given a speed of say 180, I will not be maintaining that to 4d ever, because the captain beside me will have either a) told me to slow down, or b) taken control.
Lazlo