The CAP is guidance whereas the AIP is a published legal reference document. You should start from Annex 11 and PANS-ATM, go through the AIP GEN 1.7 filed differences and the GEN/ENR/AD text before plodding on to the CAP.

Perhaps the reason for A/G frequency calling is that several share the same frequency, and they want to know if you are calling them. Of course, if the relevant ranges were published... mmm... that might stop a well known Low Cost Carrier from calling from 150 miles away on a shared tower frequency to ask for the weather from FL xxx.

DI, Nice one, now your talking my language. TDM thank you for accepting my appologies. Respect intended and also given.:) :) but what can we do? all advice will be taken on the chin.

Well, if you have found a difference, or a problem, then you could always let the ATS lot at Aviation House know. I have just identified a few things with PANS ATM, in that they do not have phraseology or sequences for some air-ground-air communications.

Mind you, our AAmericAAn friends have so many exceptions to PANS ATM filed and unfiled, all in the name of safety and efficiency according to their AIP, that it does make CVR work rather difficult to get your head round. If only they had to give clearances across all runways, not just those in use, if only they had to give the runway numbers with the take-off clearance etc...