Yes that is all very well but what then happens if on taxi in the APU is cranked up. Many SOPs require a pilot to be on the flight deck at all times while an APU is running, just in case of fire. So then, if there is no ground power available on a turn around and the APU is left running, technically shut down has never taken place. Of course the pilots might have to change over in the cockpit on the ground, while the APU is running, if they have to change places so that one or other of them can go to relieve themselves, with or without the hostess in attendance. In those cases one would always hope that the captain would be generous enough to pretend that the first officer had remained on the flight deck throughout, thus enabling him to log the total time from start up to eventual shut down of the final and absolutely last engine turning?
Best thing to do really in these days of strictly monitored duty time, is log in the log book just exactly that, the whole duty time from report to sign off. That removes any ambiguity? Does it not?
