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I'm looking for an explanation of true airspeed and ground speed.

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    $\begingroup$ The difference between them is the wind speed. TAS + Wind = GS $\endgroup$ – Jan Aug 11 '19 at 14:37
  • $\begingroup$ If you know what the abbreviations mean then this question answers itself! $\endgroup$ – Michael Hall Aug 11 '19 at 15:58
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TAS = True Airspeed = speed that you get on radar gun as airplane flies by, when radar gun is held by someone in gondola of balloon in same airmass (wind motion) as airplane.

GS =Groundspeed = speed that you get on radar gun as airplane flies by, when radar gun is held by someone on ground.

As an example: TAS of 200 knots and a headwind of 20 knots gives a GS of 200-20=180 knots. That is: the plane travels at 180 knots over ground but the air is flowing past the plane at 200 knots.

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  • $\begingroup$ Weird phone screw-up there! $\endgroup$ – quiet flyer Aug 11 '19 at 14:37
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    $\begingroup$ Feel free to add via editing (or post own); I'm not emotionally attached to ownership of this answer :) $\endgroup$ – quiet flyer Aug 11 '19 at 15:05
  • $\begingroup$ Edited to fix units and avoid issue with what you "feel" with hand being a better description of IAS than TAS. $\endgroup$ – quiet flyer Aug 11 '19 at 22:05
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    $\begingroup$ Pythagoras would like to have a word with you about your "GS" definition. $\endgroup$ – Jacob Krall Aug 11 '19 at 22:48
  • $\begingroup$ @JacobKrall - ok I get it. The radar gun should not be triggered until a/c is flying nearly directly away... $\endgroup$ – quiet flyer Aug 12 '19 at 12:06
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True air speed is the speed in relation to the mass of air you are moving in, and ground speed is the speed in relation to the ground.

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Short answer.

TAS is GS without wind. GS is TAS with wind factored in.

So, on a no wind day, TAS = GS

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