I have the habit to repeat a flight, when it was not perfect. Therefor I use exactly the same startup situations, which means same time of the day, same co-route etc. Also the weather is exactly the same, since I use FSMeteo's downloaded and saved global weather situations.And although those parameters are allways the same, I have never got identical take off speeds calculated by the FMC for identical flights. They allways differ by 3 - 5 kts.Any ideas?Wolfgang

Are you using the exact same fuel load?Cheers,JohnBoeing 727/737 & Lockheed C-130/L-100 Mechanichttp://www.precisionmanuals.com/images/forum/ng_driver.jpg

Wolfgang,I would say something is not consistent with your setting up the flight.The V speeds are as far as I know dependant on the following parameters:1. outside air temperature2. selected temperature if used (SEL TMP for assumed temp t/o)3. airport elevation4. current pressure5. gross weight6. flap setting7. wind correction8. runway slope (not simulated)9. runway condition (not simulated)10. clearway and stopway lengths (not simulated)If all these abopve parameters are constant you should get constant V speeds as well. At least that's my experience. And I did a lot of testing of the V speeds during beta.Hope it helps,

Don't forget thrust rating (i.e., max, or derate 1 or 2)Don S.