When may I log PIC time?
The "golden key" to understanding the rules of logging PIC is to always keep in mind that the FAA treats "acting as pilot in command" and "logging pilot in command time" under FAR 61.51 as completely different concepts. It's the difference between (1) having final authority and responsibility for the operation and safety of a flight (commonly referred to as "acting as PIC") and (2) writing numbers in columns on a piece of paper while sitting at a desk with a beer in your hand. They never mean the same thing and they have completely different rules. A pilot can be responsible for a flight and not be permitted to write those numbers down. A pilot can be technically nothing but a passenger in the FAA's eyes and be permitted to write time in that PIC column. In some circumstances, two pilots may sit at that desk and write numbers in their logbooks, even though, quite obviously, only one can bear the ultimate responsibility for a flight.
The known universe of rules for logging to show qualification for certificates, ratings and currency is contained in FAR 61.51. Unless 61.51 specifically directs you to it, answering a logging question by including the word "acting" or pointing to any other FAR is always a mistake. This is a simplified version of the rules of Part 61 PIC logging as they have been written in the FAR and repeatedly and consistently interpreted by the FAA Legal Counsel since at least 1980. It's limited to student, recreational, private, and commercial pilots. CFIs and ATPs can fend for themselves. If they don't know the rules, tough.
Rule 1. If you are a recreational, private or commercial pilot, you may log PIC any time you are the sole manipulator of the controls of an aircraft you are rated for. [61.51(e)(1)(i)] "Rated" means the category and class (and type, if a type rating is necessary for the aircraft) that is listed on the back of your pilot certificate. Nothing else matters. Not instrument ratings. Not endorsements for high performance, complex, or tailwheel aircraft. Not medical currency. Not flight reviews. Not night currency. Nothing. There are no known exceptions.
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