I'm an instrument-rated PPL and recently flew (M20J) solo from NJ to Florida with one leg of 280NM and 3+ landings (not counting the return flight because I had 2 passengers).
Will this trip satisfy the commercial cross country requirement of 300NM solo when I start my training next year even though I'm not currently training for my commercial?
Yes. It counts. One leg needs to be at least 250NM and you have a 280NM leg.
§61.129 Aeronautical experience.
(4) Ten hours of solo flight time in a single engine airplane
(i) One cross-country flight of not less than 300 nautical miles total distance, with landings at a minimum of three points, one of which is a straight-line distance of at least 250 nautical miles from the original departure point. However, if this requirement is being met in Hawaii, the longest segment need only have a straight-line distance of at least 150 nautical miles;
It depends.
If you go part 61, then absolutely.
If you enroll in a part 141 course, then they will have the flight as part of their training course outline and therefore will require an additional completion in sequence with their course unless they have a way to waiver it upon request, but I think they can only credit entire ratings, not single flights.
