CAP 804 Section 1 Part E Page 13
9 Guide to log annotations Case F
Pilot on flight deck but not as P1, P2, SPO or FE:
(i) Acting as ‘required’ Flight Navigator (under the Air Navigation Order)
(ii) Pilot supervising Co-pilot activities
(iii) No duties assigned (Supernumerary)
- - - - Enter time in ‘Any other flying’ or spare column and annotate ‘SNY’
he's the captain throughout, and to pre-empt the next argument, he does not need to be an instructor to hand over control to another person. I would record such a flight in my logbook as SNY, the times would not count towards any totals but my landings would count to requalify me.
How does flying an aeroplane equate with "no duties assigned"?