# Conversion airspeed to groundspeed?

How do you convert airspeed to the ground speed? So lets say the airspeed is 320knots on FL320 heading 320 with wind 32050KN

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There are many great tutorials on Google :)

Heres what I use:

TAS=IAS + FL/2

TAS = True airspeed
IAS = Indicated Airspeed
FL= Flight Level

So at FL210 (21000 ft), if your IAS=250 kts your TAS= 250+210/2= 365 Knots
(You spoke about groundspeed, well groundspeed=TAS in calm wind conditions.)

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I don’t think there’s an exact conversion . Ground speed is how much ground you cover and airspeed is how fast you move through the air.

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First calculate horizontal component of airspeed, then add the wind:

vGS=cos(θ)∗vTAS+vwind
vGS=cos(θ)∗vTAS+vwind
with θθ being the angle between the horizon and the path of the aircraft in the vertical plane.

Or, if you are unfamiliar with trigonometry (using Pythagora’s theorem):

vGS=v2TAS−v2verticalSpeed−−−−−−−−−−−−−−−√+vwind
vGS=vTAS2−vverticalSpeed2+vwind
Both formulas assume the same units being used for all speeds (vTASvTAS, vverticalSpeedvverticalSpeed, vwindvwind), and only take horizontal wind into consideration. vwindvwind is only considering the headwind/tailwind component.

No way to do this during the flight lol

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There is no way to convert the wind to ground and airspeed. (From what I know)

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This is going to be inaccurate since TAS changes with both altitude, and tempeture. Since there is no temp in the equation it is therefore invalid.

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If you want to learn how to do it. Get yourself one of these an E6-B.

Then learn how to use it. 😉
In the mean time read this for an understanding of each speed, and the relation to each other. Understanding different types of speeds

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Is that granite or furmica? Also, it’s the time for giving Brandon so send me one of these thingamabobbers ;)

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Granite of course Chris. I’ll just western union the 9 dollars to buy one since that will be shipping anyway

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Totally unrelated to the OP, but I have the same countertop lol

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Those have caused me to cry in the past, I hate them sooooo much, although they are quite accurate.

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Ummm… do you know what you typed or this from Wikipedia and c&p most people here have no idea what this algebraic equation is talking about…

Correct me if you know.

It’s pretty much self-explanatory. So lets say you are descending at the moment. so your airplane is flying with a 3* angle to the horizon, if you draw a triangle lika that one below you have your airspeed as hypotenuse so your ground speed will be the horizon line. Then you also add the wind into the equation

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Only that your “hypotenuse” is not a straight line, but rather a curve. As you descend, your ground speed decreases.

It’ll look roughly like this:

Assuming your VS and IAS remains the same and there’s no wind

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There is an option to have Ground Speed as one of your readings on the HUD(sorry if that isnt what its called). Just hold down one of the options where your yoke or any other control would be displayed and scroll through. You will find it eventually

There is no exact conversion. Your ground speed is your indicated air speed corrected for installation errors, temperature, and winds.

Uh ditto on the granite.

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