TAS vs GS

A

alexk1980

New Member
This is something stupid I have really no answer to, who knows why but, why measure TAS vs. GS? I mean GS is the speed actually travelled over the ground, isn't that what we are most concerned with anyways? Why even bother with TAS?
 
Yeah V speeds are.. at some point TAS will take place and then the Mach number. my point is GS is not enough.
 
True airspeed is very important for planning purposes. If you know your aircraft has a true airspeed of 450kts at 35,000' (it's only indicating around 260kts) you will you this as a base before calculating the effects of the headwind/tailwind which will give you groundspeed.
 
alpar80 said:
So TAS is more or less a standard. It allows for distance and performance calculations because GS varies?
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Groundspeed will vary according to the wind.

TAS will not be impacted by wind through. TAS will vary with altitude and temperature, and manufacturers can provide TAS based on these variables. Then you will see what your TAS will be, then add or subract a wind component to get the GS.

Let's say I'm planning a trip from NY-Florida (distance is 1000 NM), without any wind in my plane going 450 kts it should take just over 2 hrs. Now I look at the winds aloft and see I'll have 100kt headwind so my GS will be more like 350 kts. Knowing this I'll take about 45 minutes more fuel for the added flight time. *I'm just using numbers off the top of my head.
 
True airspeed is the speed of the aircraft flying through the air. you can figure this out on your E6B based on temp and altitude and indicated, taking into account the position of the pitot mast of about the aircraft.

Groundspeed is your speed on the ground true airspeed + or - wind component. you could be going 100 TAS in the air in your cessna, but lets say you had a direct tailwind of 20 knots your grounspeed would be 120.

and you can multiply that by 1.15 to get it in MPH.
 
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