We used to have our alternate leg based on LRC.....ATR series. I suppose the performance numbers showed it to be better. But I don't think any headwind/tailwind component was used in the calculation. I do remember on two hour diversion to alternate on minimum fuel, we had a very strong headwind for much of the flight, and the performance tables had no consideration for headwind component. All I could do was adjust power settings and see how it affected arrival calculations. Plus the wind was forecast to drop off significantly after one hour making it more difficult. Somehow we landed exactly at our 900 pound reserve fuel minimum.
As far as I know, the modern Boeing FMC's base their LRC calculations on zero wind as well.
Correct me if I am wrong but I believe these performance numbers are giving you max (or 99%) air miles not ground miles which is the important thing to know.
Last edited by JammedStab; 17th Feb 2018 at 05:19.