For the situation described in the original posts this is the definitive unambiguos answer which applies pretty much anywhere in the world.
I am surprised nobody has brought out what to my mind is a far more important consideration, that is who is actually in charge of the flight. This is non trivial because I know of one accident on a "currency checkout" checkout type of flight that occured because the who, does what, when question had not been asked. In this case the very experienced pilot sitting in the right seat had only planned on giving a bit of advice, unfortunately when the airplane bounced badly on landing the low time owner expected the right seater to "help" on the controls. In the confusion the aircraft stalled and dropped to the runway hard enough to do major damage. Ironically the owner stated if he had been alone he would have immediately gone around after the bounce.

Personally if I am asked to do these kind of flight I specifiy the ground rules before the flight.

1) I am PIC and in the event of an actual emergency, I will take control and the owner will handle the radios and read any checklists I call for and only perform further actions which I have specifically requested (this avoids the other pilot unintentionally making things worse by actions which could be at cross purposes to what I am doing). This also applies for what I percieve is a developing unsafe flight condition.

2) The flight will follow an agreed upon sequence of manoevers and any additional work will be briefed in the air before being carried out (this avoids any unplanned "hey watch this manoevers" from the check pilot. If emergencies are to be simulated I will brief how I will simulate the failure/malfunction and will always state "this is a simulated emergency" before doing anything.

3) If at any time I say "I have control" the pilot must immediately relinquish his hold on all controls without any discussion.

If these conditions are not acceptable I politely decline the flight and suggest other instructors he/she may wish to contact.

As for logging the flight......well I have enough SE PIC I am quite happy to have the student log the time as PIC as long as I am not required to attest to competancy ( eg an insurance required sign off).

To be a Co-pilot, you must be rated on type and the aircraft must have a certification requirement for a minimum of two pilots. I was referring to an aircraft certified for a minimum of one pilot where there are a number of scenarios in which two pilots may have an operating capacity, neither of which is P2. They invariably involve checks which can quite legally be conducted by a pilot who is qualified to fly the aircraft without any other qualifications. There is no difinitative answer to what you log, neither does there need to be. Log what you do, and if the CAA don't want to count it, its their perogative not to.

P.u/s
 

The answer for check rides is pilot under supervision in the majority of cases. Neither P1 or P2. Although if you reach the grade with a CFI during the flight he/she may allow you to continue the flight under P1 or P2. Only one pilot may be P1 at any time for the aircraft so that is a technicality debated between you and the other pilot and doesn't really matter which seat you sit in. Of course whilst you are P.u/s then the other person must be P1.

Pilot Under Supervision, 'wot dat den?

The pilot in the left seat needs an instructor there, the instructor is providing value to the flight - instructors instruct.

It's pilot under training, or PUT, in virtually all cases. Logging P1 is incorrect in virtually any occasion that an instructor is there as you are not genuinely in command - as you've stated, but PUS or PICUS is for successful tests, and pretty much nothing else in single pilot GA.

G

GtE (or anyone), can you help?

PICUS is for successful tests, and pretty much nothing else in single pilot GA.

"PICUS is for successful tests" I understand and am well used to, but
which regulation says "PICUS is for ........ pretty much nothing else in single pilot GA"?

Thanks

The simple answer is that there are no regulations I can think of which define its use in any other context.

G

Thanks GtE, my understanding, too.

As I see it, using plain language 'Pilot In Charge Under Supervision' matches, pretty closely, what's going on with this sort of flying .....
..... right up to the point where the instructor needs to take control.
That's the point where the instructor, most emphatically, must be the one in charge.

Logging PICUS for just the portion of the flight where take over didn't happen would be madness, although a flight where none was required at all corresponds, in some respects, to a test pass.

Thus, outside testing, if an instructor's services are required, Pu/t or Dual is the only sensible choice.

Pretty much what GtE said.

Crucial:
As many have said, getting understandings sorted out before flight is essential.
Happiness resides in common sense, not reliance on regulation.

So how do you legally record PICUS in a single-pilot aeroplane?

You don't, because there is no such thing as a Co-Pilot in a single pilot aircraft.

........unless on a successful flight test with an Examiner, then:


Examiners name goes in the "in command" box, time is recorded in the P1 box (or P1u/s box if the log book has one).


All UK practice of course - different in the USA.

"Single pilot aircraft.."

Does that mean an a/c with just one seat ? When I fly with two pilots on board because I've got two seats usually filled with two pilots, am I breaking the rules ?

How do we know that a 'single pilot' aircraft is a single pilot a/c ? If I find another pilot on board should I ask him/her to leave ?

No, he is entirely welcome to sit there - just not to "act as a pilot". He can, of course, be a passenger handling the controls under your supervision, offer opinions about the aeroplane, assist with lookout... - but you'll still be the one and only person acting as a pilot on board.

G

And in most of the rest of Europe which, unlike the UK, complies with EU law.
No, according to FCL.010 it means an aircraft certificated for operation by one pilot.You look at the EASA Type Ratings and Licence Endorsement List

So, if the single pilot a/c certificated for operation by just one pilot, has two pilots then, by implication, it shouldn't/can't fly.

Perhaps it should be qualified by the insertion of 'minimum'.which would be obvious or maximum which would disqualify two pilots.

Interestingly worded !

See CAP 804 Part 1 Section 1 Part E Para 9 Item J

Which is not compliant with EU law - my point, exactly. The fact that it's in CAP 804 does not make it legal - FCL.010 is 'hard' law which the UK does not have the right to change.

My question remains: How do you legally record PICUS in a single-pilot aeroplane?

" . . . in a form and manner established by the competent authority."

Yessir. And by extension, licensed pilots (regardless of licenses/ratings held) cannot fly as passengers on commercial aircraft. As these are typically two-pilot aircraft, any extra pilot on board would be cause for immediate grounding.

This is why commercial pilots don't wear uniforms or anything that makes them recognisable as pilots, when they're on board a commercial airliner as pax. It keeps them under the radar so the authorities don't know an illegal flight (3 pilots on board a 2-pilot aircraft) is taking place. And it's also the reason why flight crew don't appreciate private pilots identifying themselves to them before take-off: It leads to all sorts of unnecessary complications and paperwork. Best to stay quiet about it or you run the risk of being offloaded.

But the 'form and manner' must still comply with 'hard' law and the UK's does not.

Alice in Wonderland lives on ! For unrealistic legalese, it almost rivals the limits for flight in VMC.