[Spinnetti]

your take off calculations are based on a PBY FM. That PBN-1 does not have a PBY FM. The FM of the Nomad (in game) is more powerful than a correct PBY-5

You may be correct Thud on the FM, but those figures were based on the PBN-1. The same tests were conducted on the PBY and the tests results were either the same or within a few percentage points. Tests showed the takeoff FM is not 100% correct. Then again the seas, wind, and temperatures are ideal, so that could be a factor also.

Well, regardless, the point might be that the AI is a bit off for sea planes take off? Or was is simply the mission author didn't set waypoint elevations conducive to the desired launch trajectory? Interesting discussion anyway..