I have read Dr. Vaos's post on how to accurately calculate fuel on the Ngx here http://forum.avsim.net/topic/340682-will-a-fsbuild-aircraft-performance-data-profile-be-available/page__fromsearch__1He mentions that one has to enter the isa and winds in the perf init page. How does one go about finding these values?

I'm not sure about ISA... isn't this just a standard 1013 (29.92) and 15C? The cruise temp is included with the ASE flight plan briefing. The winds aloft can be also be found with Active Sky Evolution (ASE)... so can the climb and descent forecast winds. It's a little tricky to understand forecasts, but for me, ASE has the winds for each waypoint of a flight plan for altitude from 3000-39000 in 3000 ft increments (sorta). I look at the FMC for the altitudes programmed for the climb and descent and then interpolate the difference if in between altitudes given by ASE... voila, now the fuel calc and ETA's are as close to perfect as can be. TOPCAT is a must in determining Derates for t/o... if you get serious enough to get that far.

I'm not sure about ISA... isn't this just a standard 1013 (29.92) and 15C? The cruise temp is included with the ASE flight plan briefing. The winds aloft can be also be found with Active Sky Evolution (ASE)... so can the climb and descent forecast winds. It's a little tricky to understand forecasts, but for me, ASE has the winds for each waypoint of a flight plan for altitude from 3000-39000 in 3000 ft increments (sorta). I look at the FMC for the altitudes programmed for the climb and descent and then interpolate the difference if in between altitudes given by ASE... voila, now the fuel calc and ETA's are as close to perfect as can be. TOPCAT is a must in determining Derates for t/o... if you get serious enough to get that far.

Thanks for the reply. But do you know of a free way to find these or is payware the only option?

Well, it will be very time intensive but a couple of good sites are... http://www.wunderground.com/ - Anything with a wunder in front of it is good ;), and it's world wide another one is NOAA - but this is US only, you may be able to find other world locations, by searching "winds aloft" in google.http://aviationweath...ts/nws/fdwinds/ I recommend ASE for your own sanity of doing these calculations. But, if you like math, go ahead and enjoy. It takes less than a minute to get this info via ASE, and it offers a whole lot more... for instance more weather layers of clouds than allowable by normal default FXS. EDIT: If you use FSBuild, ASE also populates the winds for it too, which helps a bunch in planning with FSBuild.

Thanks man, I appreciate the help. Those sites are great, it doesn't bother me to do the calculations.

He mentions that one has to enter the isa and winds in the perf init page. How does one go about finding these values?

Just if anyone cares, but I recently found this site to be quite useful. http://www.flightwork.com/weather.html