Originally Posted by
PPWorlds
Can't believe the discussion going on here. 25 to 30 degrees? Of course you recalculate performance
Your Flex 75 is from the 25 degree data so you need to recalculate your flex temp for 30 degrees otherwise your reduced thrust Flex 75 aircraft wouldnt make it within the limits of the field, obstacle etc OEI. Seriously guys.
Do you know what assumed temperature is? When you run the performance it gives you a Flex/assumed temperature. That temperature is the highest temperature you can safely take off and meet all the required distances/gradients, and that number is used by the fadec
instead of the OAT to set N1/EPR. So unless it is hotter outside than your flex number you can take off. The actual OAT doesn't matter, as long as it is below the Flex number.