This is taken directly from the Fedex FCOM As far as I'm aware Max Flex on the PMDG aircraft is 60c Just curious as to why they didn't model the full 70c like the real aircraft?FLEX - Allows pilot entry of an assumedtemperature for a FLEX TO thrust rating.Range is from the present Total Air Temperature(TAT) indication to 70

Its been quite a while since i flew the MD11 (been dusting off my 744) but i THINK you can enter 70c in the MCDU....its just that theres no difference in thrust between 60 and 70.....so its sorta simulated i guess

This hardly qualifies as an answer but I can't recall flexing more than 50 in the MD11. Maybe that's a reflection of the weights I typically have on board but I'd have thought it would be pretty rare to have light enough loads to flex that far.

FLEX is, among other things, a function of TOW, so if you have never operated the MD-11 on a long runway at near sea level with a bit of headwind, lower OAT, and lower TOWs, you will not have had the opportunity of entering much higher than 50... I have got it to about 58 I believe, then again, that was a short, light hop from a long piece of tarmac (EDDF - EGLL)Andrew

Thanks for the input Mark, are your comments based on real world experience or are you just talking about the PMDG version?I regularly get given a 60c Flex when flying short hops around Europe at Max ZFW eg EGSS-LFPG LFPG-EDDF EDDF-LIMC It seems that the Max Flex TOPCAT gives is 60c What program are you guys using?Regards

Using the FLEX calculation tables that are available (or were at least) in the avsim library... have always worked well for me... I must look into getting TC though...Andrew

You would be very hard pressed to find a situation where a flex of 70 would qualify as normal. The highest I have seen in a normal situation is 60, but usually 55.

Yes true, I only wondered because on a Empty ferry flight from EGSS -LFPG despite using ballast fuel and Max Flex the aircraft is a handful on T/O when light. The real aircraft is certified to T/O empty on two engines so it goes to show how much excess thrust is available. It also makes me wonder how the real thing handles empty when Flex is not authorized, eg windshear predicted on climbout or pressure is below 1000mbRegards

I just calculated an empty weight ferry (20K ballast in Upper Aux) from EGSS, showing a max flex of 50 on the PW version. The MD-11 is very overpowered, but then again, so were the DC-10s. They were also authorised for two engine ferry flights. Ask most MD-11 pilots and they will tell you that they prefer the DC/MD-10 because of the greater feel of the aircraft. The MD-11 is squirelly, especially on approach.I almost forgot, the manual that you are referring to outlines the system restrictions. There are further company authored restrictions in some of the other manuals.