Noggin - what has sitting watching another pilot show his or her skills on a rental checkout anything to do with having an instructor rating and instructing? - you don't even have to have a pilot's licence to do that! The potential renter with a valid rating can be pic and all the other guy is there for is to approve it all on behalf of an owner.
>>an instructor flying with another pilot in any form of check out it is countable as Instruction. JAR-FCL 1080 (c) (iii)
All your reference says is that the instructor can log as P1 when acting as an instructor. I don't argue with that (who would?), but for just rental approval checkouts, an instructor isn't instructing. If the instructor IS instructing on this flight for some reason, then of course it is p1 and pu/t, but nothing to do with p1/s.
(I do notice that instructors are always 'he' in that regulation you quote - is there a general JAR statement that 'he' can be 'she', and if not, what are the consequences?)
>>If the checkout is acceptable you can sign their log as PIC U/S for: Any form of flight test other than for the grant, renewal or extension of ann aircraft rating Ref: CAP 53 Part 1 App G Case J. JAR-FCL 1080(c)(ii) uses the term SPIC.
This CAP 53 reference you quote is specifically talking about TESTS - I think the only point we disagree is that I can't accept a rental checkout is a TEST! This regulation is used for tests like an IMC rating test, which is a personal rating not an aircraft rating which is why it talks about p1/s for passes, pu/t for failures.
I didn't understand the reference to 'SPIC' -isn't that just shorthand for student solo time (Student p/ic)?