Originally Posted by
mn_test347
Is it not likely that the take-off performance data tops out where it does because that's the limit that the aircraft can operate with a reasonable payload? Although not impossible, wouldn't a manufacture be silly to build an aircraft for ISA+45ºC and only certify it to ISA+35º.
I think it is more likely that they don't bother certifying it for temperatures that are only experienced very rarely anywhere in the world.
I fly a BAe146, certified for ISA+35, and there is nothing particularly limiting about the 50º line in the performance charts for a descent sized runway (>2000 m).