I think it's pretty obvious why the limit, the bigger it is the more damage it will cause on the ground should you incapacitate. Even truck drivers have higher standards for medical than the ordinary driver for the same reason, and dangerous goods drivers higher again.
If you crash a Warrior into a house it is much the same result as a car doing the same at speed, that applies up to about Baron/Seneca size. Beyond that the aircraft get significantly more able to both do significant impact and fire damage due to fuel loads.
In the past weight limits usually were set around allowing a particular type as the maximum, 3500kg allowing Navajos and Cessna 400 series. 5700kg/12,500lb was roughly half a DC-3 which was considered what would be the reasonable upper limit for a light/personal aircraft, set long before the big piston twins and such came about. The reason I understand for the 12,500lb was to protect airline operators which were using mostly DC-3s at the time, and by restricting other aircraft to half of ones weight below that placed a protection on the amount of passengers a smaller operation could carry. That then place protectionist rules for airlines to operate safely and at profit, or something along those lines.
Last edited by 43Inches; 22nd Jun 2023 at 10:11.