I believe that you will find that the answer lies in the takeoff analysis program logic. I’m presuming that you have a chart that states it’s based upon improved climb, but it doesn’t actually tell you the percentage of the speed increase.
One of the program inputs is
optimum improved climb & V-speed, for the examples that I have examined, the improved climb index changes between 0-8 units depending upon the weight/wind. The tailwind will have an impact on the distance required from Vlof to screen height, therefore to achieve the same screen height at a specific weight in a given distance, the VR has to change, as will the V1. So for a zero wind calculation, it may use 5 units but 0 units for the tailwind. The zero wind takeoff distance will be less than TODA, the tailwind distance will be limited by the TODA. You
cannot use the tailwind v-speeds for zero wind…. Unless of course you have a good lawyer
Its hard to examine these things when they come from an outside vendor, but I suggest that you look at the Improved Climb tables in the Operations Manual, and try to replicate the takeoff weights/speeds manually.
Safety Margins? Apart from the 50% headwind/150% tailwind, I don’t know of any additional safety margins when operating with a tailwind.
now, that might be a bit embarrassing It wouldn’t be the first time, but before I make a fool outta myself, I gotta check that my home version of the program is the latest version.
Mutt