Aha,
Perfect example of ideal vs. real world application.
You apply a 1.25% safety factor to, say, a Caravan (4000kg+ MTOW) and see how far you get with a strip that might be less than 700m long. You may be already weight limited on the take off, but apply 25% to the manufacturer's (already adequate) data and you can't operate at all.
Not good for continued employment.
Last time I got ramped, the FOI wasn't particularly happy about the CASA manual being in the aircraft with the manufacturer's POH at all.
