I know that when you are driving the tacho is in driving mode and when you are loading/unloading you switch to other work but when is it best to use poa.I’m guessing it is when you may be in a queue waiting to load somewhere.
POA can be used when you are told in advance of a specific time delay whether that be before you get to the place or on arrival at the place.
Whether you use it or nor is up to you - Most would use BREAK and not POA if they get paid for breaks
I never ever use it if i’m not driving or resting i’m working!
ROG:
POA can be used when you are told in advance of a specific time delay whether that be before you get to the place or on arrival at the place.Whether you use it or nor is up to you - Most would use BREAK and not POA if they get paid for breaks
Just to clarify, the wording states:-
Periods of availability 6. - (1) A period shall not be treated as a period of availability unless the mobile worker knows before the start of the relevant period about that period of availability and its reasonably foreseeable duration.
Hence, besides becoming aware of delays, by direct questioning, or by word of mouth, or by reading something on here, previous experience would also count towards such knowledge, as would a visual assessment at the scene. Just because one arrives at a location and ‘assesses’ a two hour POA, does not mean that because they then then get attended to after 30 minutes, that the original ‘assessment’, and therefore the period of POA, need be discounted. 
The operable word here is ‘foreseeable’. Or, to put it another way, “How big is a crystal ball?” Mine is absolutely massive. 
Pulling into the Services for a toilet visit. I expect to get blocked in. POA.
Pulling up to a gatehouse awaiting the ‘biro monkey’ to spring into life. POA.
Alright. I’m jesting. But the rules are so loosely written that for anyone with a modicum of common sense, virtually any viable argument would suffice.