Most (all?) airlines require you to do some jump seat rides as part of your training. You are there as supernumerary crew and cannot log the time as P1, P2 or anything useful. If you want to record the flight it can be entered in the logbook under SNY with the time written in the 'other' column or comments section. This time does not count towards your logbook totals but is relevent for crew duty times and pay (hopefully).