ATC vs Pilot Airspeed discrepancy

But you fly from indicated airspeed, all this rubbish about Indicated etc is based on a value that changes constantly, @Henrik_B is right, all that changes is the throttle position.

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No true airspeed and ground speed are not one in the same.

if you don’t have the auto pilot selected to adjust for the wind and maintain that 200 KIAS then what happens? Your indicated airspeed increases correct?

Sorry that sentence seems arse about face? I dont get it, if there is a headwind, the actual wind speed passing over the plane has changed yes, but the speed of the plane travelling through the air doesn’t change?

No your plane would slow until the thrust is equal to the drag again. If you introduce a headwind to a plane and don’t give it more throttle to compensate for the head wind the plane is going to slow down until the induced drag from the head wind equals the thrust of the engine again. Does that make sense? Same as a tail wind if you introduce a tailwind the drag decreases and the plane speeds up until drag and thrust are again equal. @Makeaflightforfun

Wow this has confused me now. To clarify, the atc sees only airspeed, and issues a speed request for the pilot in airspeed? The pilot changes their speed in airspeed? I mean if we as atc are expected to know the pilots ground speed by calculating wind speed/direction then that seems unreliable. I mean if I see an aircraft flying heading 220 at 400kts and the current wind (at airport ) is 180 at 10kts then I’m just guessing the ground speed is slightly higher at 420kts?

@mhhodges76 we see ground speed as ATC but give airspeed for pilots to follow

Just read what Tyler said and you will be good ignore the rest

Ok so pilots can see other aircrafts airspeed only but we as atc see an aircrafts ground speed? if other players are able to see other players airspeed then it should be easy for an atc to have access to both.

This is a classic who shot John. It’s like a dog chasing its tail! Like the man said ATC’s got the dot. Trust them to get it right LOL. Max Sends

Hi Tyler - I think you may need to have another conversation with your community of Advanced ATC. Some are still asking me to slow down to a speed which is actually faster than my KIAS. For example I am cruising at 180kts (KIAS) and been told to not exceed 210kts. This confusion is exacerbated when at higher altitudes. Rather than get a barrage of slow down messages or risk being ghosted, I now fly assigned airspeed at groundspeed which I know is wrong.

That means just don’t go above it, it doesn’t matter if you are or are not above it, it means simply, don’t go above that speed.


There have been recent occasions when I’ve been sent multiple ‘do not exceed’ messages followed by ‘please follow instructions’. This is why I slow down and fly assigned airspeed at groundspeed. I’ve also noticed other pilots doing the same thing.

Reply unable if your ghosted screen shot it and it will be delt with.

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Who is right???
If ATC controllers see Ground Speed why not count Ground Speed and not Airspeed
It will be very less complicated!!!

Both are correct aircraft fly off of KIAS so that’s what speed assignments are given in.

ok and when a controller are confused? he told you 250kts, we see 280kts, you are 250 KIAS,
he don’t understand…
What are the proof that he are really flying 250 KIAS? We can’t see that

I just addressed it again. Thanks for the feedback and let me know if you see any other issues with specific scenarios!


this issue is waaaaaaay solved. If a controller misses it, he is probably new and training. I see no more problems at all in this issue.

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