Relax, Champignon. Next time I'll mark my post with
to make my point clearer (for some).
No need to invoke logic; relevant for the logging of P2 hours is
JAR-FCL 1.080 (c). It says that copilot time can only be logged from the pilot's seat. Now pay attention kids: there are only two pilot's seats on any ole aeroplane currently engaged in commercial air transport in JAAland. Jumpseat is (surprise, surprise) not a pilot's seat.
What I wrote about 'no chance of being caught' is, sadly, only half-a-jest. The practice of logging co-pilot time from jumpseat is quite widespread in some parts of JAAland and ones who do not indulge in it, put themselves in disadvantage relative to their peers who do. Especially as some local CAAs have problems even catching people who outright falsify their loogbooks by logging flights that never took place. At least, for jumpseat ride there's journey log that matches your logbook.
You think I'm exagerating? Well, not everyone replying here was joking.