And yet despite all these points regarding responsibilities - and all these points mentioned here are true, we still have this faintly ridiculous Pilot in Command Under Supervision thingie which should mean nothing - yet it goes towards logging what is basically fake command hours in order to meet licencing minimums.
The books says any decision made by the pilot logging PICUS that is counter-manded by the real pilot in command, results in the whole sector being down graded to a mere co-pilot time. That's a real joke and my guess is that it rarely happens. PICUS is a great rort. All it means is the captain has given his co-pilot a sector. It seems logging co-pilot time is below the dignity of the co-pilot.