Originally Posted by
hans brinker
I probably didn’t express myself correctly, and I would definitely hesitate to question your expertise.
But I have always read it as: Assumed/FLEX will set the power for that temperature. If the actual OAT is lower, as it should be, you will have an additional margin. If the OAT rises, that margin will decrease, but up to OAT reaching FLEX your FLEX power setting should be safe to use. You say that there would be no extra margin because the calculation takes OAT into account, and if OAT rises you would have to do a recalculation. I obviously understand that you are correct if there is no extra margin, so will go back to my books.
Books tell you nothing more than what I have produced already. OAT and wind intersection gives you MTOW which will decrease if OAT goes up. But many times it's beyond structurally limited wt. When you want flex you enter wind find ETOW then on the left you get flex. There's no OAT column. Which is checked later against flex. No performance document tells you to recalculate performance with OAT rise.