What kind of airspeed does a (3D) GPS measure? Assuming a GPS receiver is advanced enough to compute 3D position/velocity with reasonable accuracy, it can indicate not only the aircraft's ground speed (which ignores altitude changes), but something akin to airspeed as well. If there was no wind, this would be equivalent to true airspeed. In reality there would be wind so it is &quot;TAS minus wind&quot;. Since this completely ignores the actual air (the value would have been the same if there were no atmosphere), however, calling it anything related to &quot;airspeed&quot; seems like a misnomer to me.
Is there a standard terminology for this kind of velocity measurement?
EDIT:
It seems my question was quite vague and providing more detail about what I'm trying to do would help. I'm writing the documentation for a GPS-based tracking device, which would be used in fixed-wing aircraft. The GPS is exceptionally good, with very high precision and quick sampling rate. It even provides very accurate speed, which is Doppler-shift based AFAIK. This data will be sent through telemetry. I'm trying to label the data channels in a way that would be useful for aviators down on the surface, so I'm trying to familiarize myself with the proper terminology. Therefore if I label this (&quot;3D&quot;) velocity as &quot;airspeed&quot; (indicated/true airspeed), it will be misleading. If I label it &quot;ground speed&quot; (which is 2D), it will be misleading as well. My question is only whether a standardized name for this type of velocity exists; if there's nothing widely used, I'll just coin a name of my own (e.g. &quot;3D velocity&quot;) and explain it well enough in a tooltip.
Q: &quot;What kind of airspeed does a GPS measure?&quot;
A: &quot;None whatsoever.&quot;