Luftwaffle
Our ATC manual states:
When given the instruction "cleared for immediate take off" it is expected that the pilot will act as follows:
(a) At the holding point, taxi immediately onto the runway and commence take off without stopping the aircraft. (Not to be given to Heavy aircraft.)
(b) If already lined up on the runway, take off without delay.
Immediate means immediate. There shouldn't be any question of how long you can take to depart immediately.
Often a normal departure turns into an immediate one because the guy lining up takes so long to get onto the runway. An average landing roll, from the time the arrival passes you to when he vacates, I would say, is about 45 seconds. It shouldn't be too much to ask that you are lined up when take off clearance is issued, rather than just crawling across the holding bar as the preceding is vacating, should it?.
I had a guy today who was raring to go. He was cleared to line up after the landing at full length with a lighter type lining up further down to depart ahead of him. Before the arrival had passed him he says "Can we have the stop bar down?" I'm all for a bit of expedition but this was going a bit far!
To answer the question you posed: Yes I would prefer you to say no if unable to accept an immediate, but would qualify it by saying don't turn every departure into an immediate by dawdling onto the runway.
When operating in mixed-mode (arrivals and departures on the same runway) I judge the arrival gap to give a time interval between the arrivals to allow a departure and permit landing clearance usually by about 200 feet.
In segregated mode (departure and arrival only runways) you should be ready to go as soon as the one ahead is airborne.
You find that at "quieter" airports pilots take longer than if they were at one of the busy airports because they don't see the need to get on with it.
I'll stop now, I'm turning into cossackwaffle!!!
(typos)
[This message has been edited by cossack (edited 31 January 2001).]