If I know the IAS and GS (with directional components) of an aircraft, can I derive the wind speed and direction?

I'm working on an application that simulates the flight of an aircraft. Another application that takes as input, the computed trajectory of my aircraft, which includes the IAS and GS of the aircraft (at points along the trajectory) needs to know the wind speed and direction at those points.

I think it is possible, but am not sure, to isolate the wind speed and direction using the IAS/GS (or both).

Can someone confirm this? Is this a reliable way to do this? Do I need other information to complete the calculation?

  • 1
    $\begingroup$ Possible duplicate: How is the wind direction and wind speed measured in flight? $\endgroup$ – Fred Larson Mar 10 at 15:48
  • $\begingroup$ Yes, in part; I had read that but still needed to ask for my own clarity. I just needed to confirm for myself that it was possible to extract the wind at a point from the data available (in my case, I have IAS, GS and TAS, thought in my question I thought I needed IAS and GS only, but the answer cleared that up). $\endgroup$ – PKCLsoft Mar 10 at 19:10

No, you need the True AirSpeed (TAS).

The Indicated AirSpeed is not a realiable measure of it, since it is not even calibrated against the instrument mounting position and is not intended to measure the speed relative to the airmass (what you actually need to derive the wind components).


I use to fly a small gyro. It's fitted with an old, simple GPS, so that I always know the instantaneous ground speed. If, while flying level and at constant engine rpms, I describe a complete turn, there's a point of that circle where the groundspeed reaches a minimum. The gyro's heading is, at that point, the wind direction. And the wind speed is the difference between the airspeed (TAS) of the anemometer and the ground speed as shown by the GPS...


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