Here are the FAA rules pertaining to logging (and being) a PIC...
Some for you confuse PF and PIC, or PNF and SIC... not the same thing.
Take your eyeglasses... many of you dont have 20/20 vision -
Or maybe do not understand ICAO level 4 English.
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FAR 1.1 (easy to remember the numbers, is it...?) - Definitions...
Then we go down the alphabetical order to letter P.... for Pilot in Command.
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Pilot-in-Command - means the person who: -
(1) Has the final authority and responsibility for the operation and safety of the flight.
(2) Has been
designated as pilot in command before or during the flight, and -
(3) Holds the appropriate category, class and type rating, for the conduct of the flight.
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If you fly under FAR 91 (executive flights) - you could log PIC if -
(1) You are qualified on that type of aircraft.
(2) You are current as PIC (see rules that apply with FAR 61.58) that is aircraft current by type, with a PIC proficiency check in the last 12 monrhs.
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If you fly under FAR 121 (applies also to FAR 135) - you could log PIC if -
(1) You are qualified as PIC on type aircraft (type rating) -
(2) You have performed 3 landings in the last 90 days on the aircraft type -
(3) You have a current 6 month PIC instrument check -
(4) You have a current 12 month PIC line check -
(5)
You are named as PIC of the flight on the dispatch release and flight plan.
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In the case you are a "Cruise Captain" with a crew of 3 pilots, in which you are the SIC "Second Captain" - you can log as PIC all the time you fly while acting as PIC/PF... With my airline, our cruise captains on the 747-400 and the A-340 are logging 1/2 of the time as PIC, and 1/2 of the time as SIC, as an approved practice.
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Happy contrails