The Navigraph takeoff perf calc for the Avro is inaccurate. Flex coming up as 50 degrees, sometimes the TRP does not even allow me to dial such high value in. Other times I run out of runway and climb out in a 100 fpm manner or even better, the jet nosedives to achieve the desired speed.
Again, this is supposed to be a Professional stuff, allegedly study level. At this price range, I expect the devs to either provide a proper calculator (tool) or at least supply perf charts so we can properly obtain the required values. Otherwise the feature (flexi) is unusable, at least in a realistic manner. Derates absolutely require tools to determine their values.