One the flightplans, when you guys post something like "N0483F370"...is the N0483 483 ground speed or is that 483 true airspeed, or is that 483 indicated airspeed??? From the sim, it looks like 483 true airspeed which makes the groundspeed like 540-550 knots :)))) Woo hoo for fast 747's :)

Hi Zach,It's the true airspeed and can be reported in other formats, too.K0865S1110 // TAS 865km/h, flight level 11100 metresM080F350 // Mach 0.80, flight level 350Kind regards from cold Finland, Matti.

Hi,Ground Speed = True Air Speed + WindSo, It doesn't have to be 540-550 GS. If you have to flyinto the wind it would be less than 483...You can't say what the wind aloft is when you planyour flight. That's why it is not used in a flightplan.True Airspeed is based on the Standard Atmosphere...Ciao,FlyerNL

Dear FlyerNL,I'm afraid that I have to correct your words. Actually you can say the ground speed when planning the flight. If it was otherwise, planning the true airspeed would be impossible. This is because of data that is used in planning, temperature and wind data is usually bound together. Also the fuel and time planning would be impossible without the wind and temperature data.Regards, Matti.

Hi Matti,Yes, I understand it... I meant that they can't say what would bethe exact ground speed each time. They use wind aloft data for abig area. But that area doesn't have all the same wind, it changes... If they used ground speed their flight plan would have a lot of speed changes... :-)Based on TAS, the standard atmosphere doesn't change very much...But, thx for the info ;-).... (I hope I am right :-roll)Ciao,FlyerNL

Hi FlyerNL,You are almost correct. Temperature is a minor factor and wind a major factor in time calculations, but the both are effective factors.Regards, Matti.

Cool, so I think I understand what groundspeed and true airspeed is (speed without any affecting factors like wind and temperature, no?)...so what is indicated airspeed? Going a little off topic here, but I guess this is necessary for flightplanning, right?!Thanks for all your guys' help!

Temperature affects in TAS. Thumb rule is 1 knot per 1C difference from standard air temperature. The colder, the slower.IAS is the air speed in the pitot tube. Because upper air is thinner, IAS is smaller at F300 than at sea level if TAS is the same. IAS is a very good indicator for safety speeds etc. because it's straightly related to the air mass that keeps aircraft on the level flight. The only one who's really interested of IAS is the pilot. It's the reason why TAS is used in flight planning (ATSes don't want to know your sinking speed, they want to know your real speed and estimated times).Sorry for confusing use of English, I'm a little bit tired now. It's 0121LMT here and just closing flight simulator after the flight of six hours and nine minutes.Good night for everyone, Matti.