Flowman,
Thanks for the explanation.
I guess that the same thing could be done by say changing the speed so that the aircraft reached the regulation point earlier.
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TIO,
The local orders at your station and the AIC posted by squibbler, don't totally tie in with the AIP.
However, having spoken to a person who seems to know how to weasle out of every slot restriction, they suggested that one can depart at 15min prior to the planned EOBT without any requirement, furthermore, ATC has a window within which they can let you go if it suits local traffic and that brings us back to 20min prior to EOBT.........so taking a slow start and slow taxi, one can have an actual off blocks time 30 min before the planned one without having to do anything.
They also said there is no point in going throught he handling agent in most places. Far better to ring the appropriate Flow control desk with the number in the AIP. When they ask why you rang, say ATC are to busy to make the call
Regards,
DFC