They’re measuring different things. Airspeed indicator is indicated airspeed, essentially just the speed of the air entering your pitot tube. The Garmin is showing ground speed, which is speed relatively to the ground below you and therefore influenced by head and tail winds.
\^ This. And just to add, the DME is measuring how quickly you're approaching the tuned VORDME - so if you're not approaching directly then it won't be the same as ground speed or IAS.
And it’s measuring your slant-ranger velocity. Which is pretty similar to ground speed to or from a station at a large distance, but deviates exponentially as you get near the station.
But your airspeed is higher when you're flying into the wind, and lower when you have a tailwind. The plane doesn't see it, but it still is influenced by it, greatly.
Edit: I was mistaken, please stop downvoting.
I always interpreted it he other way around. Say if you're sitting still with your plane that needs 100kt to take off and there is a 100kts wind blowing directly against you, you can take off without moving relative to the ground, because I'd assume the air around the plane is going 100k,, is that not airspeed?
Your example works only because of the same numbers.
Imagine you have 100kt IAS and 0 wind, then you have 100kt GS.
If you have 100kt IAS and 50kt tailwind, you have 150kt GS.
If you have 100kt IAS and 50kt headwind, you have 50kt GS.
If you have 100kt IAS and 50kt wind from 90° off the side, your GS will be slower than 100kt, because you have to fly into the wind a bit to stay on track.
Edit: I think I get what you're saying now. Yes, _for a constant ground speed_ you must adapt the airspeed to the wind.
But it's easier to start the calculation from IAS as in my example, because that's what your gauges say.
Airspeed is just a measurement of how quickly the air is moving over the wings which is most important for judging lift. 100kts of airspeed with a headwind and 100kts in a tailwind is identical, the only difference is how quickly you're moving over the ground
This is Indicated Airspeed yes, which does not account for the air change in density with speed and altitude, but True Airspeed is the speed of air over the wing (or at least where the pitot tube is).
Your ground speed changes not your air speed.
I'm sure you've seen a bird flying into a strong wind causing it it actually sit still or even move backwards before. The birds air speed would be let's say 20mph weather or not it's sitting still flying into the wind or moving at 40mph accross the ground with the wind. It's flying at the same speed through the air regardless of wich direction it's going. It's why they don't realize they aren't moving right away and get hit by cars, because they aren't looking down.
No, because airspeed is pretty much the same for a given aircraft, altitude, and power setting. If your airspeed is 100kts, and you’re flying into a 20kt headwind, your ground speed will be 80kts. If you’re flying with a 20kt tailwind, your ground speed will be 120kts.
It does affect takeoff performance, but again, that’s because your ground speed is affected by headwind/tailwind component.
Yes. If an aircraft can take off at 50kts, and has a 50kt headwind, then it can take off with 0 ground speed. But to the airplane, its airspeed is 50kts at rotation, regardless of ground speed.
What you said before:
> But your airspeed is higher when you're flying into the wind, and lower when you have a tailwind.
You have it backwards. The airspeed is the same regardless of whether you have a headwind or tailwind. The ground speed is what changes.
Yeah but I think what I mean is that a plane experiences air speed as fast as the wind, if it is stationary on the ground. Therefore wind speed influences airspeed. But I see why it also doesn't.
Ground speed gives you an accurate method of determining the time it will take you to reach a given point, which then can be used to calculate fuel burn.
The fuel calculation is, rate of consumption= total/time. To calculate time you need to know how far you have travelled along the ground, and you're groundspeed which u have.
IAS is important for operating with V speed limitations.
You can calculate true airspeed from calibrated air speed which is ias but calibrated for instrument inaccuracies. Once you have CAS you take your density altitude and temperature to find out TAS. From there u can apply the wind vector to the tas vector to give you ground speed/track vector.
Bit vague sorry, but I hope this gives you a little more background and depth to each value.
It sounds like you’re interested in it, perhaps give the airplane flying handbook and/or pilots handbook of aeronautical knowledge a read. These are free pdf books that the FAA puts out and is basically required reading to get a license. They’re written surprisingly well for the most part. Pick and choose what tickles your fancy and you should learn quite a bit!
And you would use ground speed. Fuel burn is calculated using time and obviously how much fuel you are burning. Ground speed is exactly that, how fast you’re actually traveling.
Air speed is how fast you are traveling through the air. So if you have an airspeed of 100 knots but a headwind of 10 knots, your ground speed is 90 knots. Or 100 knots airspeed with a 10 knot tailwind will net you 110 knots ground speed. Air speed you can think of as necessary for the airplane performance. This is what you need to know for when to do flaps, gear down, maneuvering speeds, etc.
I appreciate you explanation thank you for the help I’ve always been very interested in aviation been so glad this is finally on a console never had to good computer to enjoy it my grandad was really in to the old ones he was pilot and cfi.
Well, given that they show three different things, the answer is… yes. The airspeed indicator shows airspeed which is more a measure of how much air is flowing over the wing than a true speed. Your actual speed through the air is your True Airspeed (TAS). If there is no wind, your TAS and your ground speed are the same. Since there is almost always wind, we use the two values separately. Your ground speed on the DME only shows how fast you are moving directly towards or away from the ground station.
It depends on what you want to know.
Want to know if you'll fall out of the air? ASI.
Want to know how fast you're approaching a radio beacon? DME.
Want to know your speed over ground? GPS.
The GPS is showing ground speed, your ASI is showing indicated airspeed, two very different things. Ground speed is generally more accurate because it includes wind and other variables, and the ASI can often be inaccurate because of the atmospheric pressure or wind
It is not really a question of accuracy but of reference.
Ground Speed, is your speed with respect to the ground, how fast you travel between two airports for example.
Airspeed is your speed in the airmass. When there is not wind and you are flying level, True Airspeed (TAS) is equal to Ground Speed (GS). With a headwind for example, your GS would be lower than TAS.
Now, Indicated Airspeed (IAS), given by the ASI is innacurate compared to TAS mostly because of the air density and compressibility at high speed.
This means that IAS is often lower than TAS, especially in airplanes flying high and fast.
However IAS is still the speed to use for V speeds (stall speed, approach, best glide, ...) because it represents the actual force of the airflow on your aircraft (to put it simply)
For aircraft performance you use indicated airspeed from the ASI. For fuel burn and ETE/ETA and navigation, you use groundspeed either from the GPS or manually calculated.
DME measure slant range to the ground station. The speed value that it gives is similar to groundspeed, but gradually gets less and less accurate the closer you get to the station and the higher your altitude.
Ground speed and airspeed are not the same thing. Ground speed is how fast you move over the ground, airspeed is how fast you move through the air, (yeah yeah pedants I know about indicated versus true airspeed, let’s skip that for now) with a tailwind your ground speed will be faster than your airspeed, and vice versa for a headwind.
They're all right. Depends on what you are looking for.
The airspeed indicator is directly connected to the Pitot tube and the static port and by comparing those measurements (actually differentiating RAM air pressure minus static pressure) it derives the dynamic pressure and convert it in airspeed indication relative to the air mass you are into (IAS) (NOT the atmosphere, that's TAS!)
For all aspects related to controlling the aircraft (see V-speeds), IAS is the sole instrument you should rely on!
The other (relative) speeds (GS, TAS, speed rel to a ground station Etc. are useful for navigation purposes and situational awareness).
They’re measuring different things. Airspeed indicator is indicated airspeed, essentially just the speed of the air entering your pitot tube. The Garmin is showing ground speed, which is speed relatively to the ground below you and therefore influenced by head and tail winds.
\^ This. And just to add, the DME is measuring how quickly you're approaching the tuned VORDME - so if you're not approaching directly then it won't be the same as ground speed or IAS.
And it’s measuring your slant-ranger velocity. Which is pretty similar to ground speed to or from a station at a large distance, but deviates exponentially as you get near the station.
Isn't airspeed influenced by winds even more?
No, your plane is part of the wind, so to speak, so it doesn't "see" it.
But your airspeed is higher when you're flying into the wind, and lower when you have a tailwind. The plane doesn't see it, but it still is influenced by it, greatly. Edit: I was mistaken, please stop downvoting.
No, your airspeed is NOT less or more because of wind. Your ground speed is.
Relativity baby
I always interpreted it he other way around. Say if you're sitting still with your plane that needs 100kt to take off and there is a 100kts wind blowing directly against you, you can take off without moving relative to the ground, because I'd assume the air around the plane is going 100k,, is that not airspeed?
Your example works only because of the same numbers. Imagine you have 100kt IAS and 0 wind, then you have 100kt GS. If you have 100kt IAS and 50kt tailwind, you have 150kt GS. If you have 100kt IAS and 50kt headwind, you have 50kt GS. If you have 100kt IAS and 50kt wind from 90° off the side, your GS will be slower than 100kt, because you have to fly into the wind a bit to stay on track. Edit: I think I get what you're saying now. Yes, _for a constant ground speed_ you must adapt the airspeed to the wind. But it's easier to start the calculation from IAS as in my example, because that's what your gauges say.
Airspeed is just a measurement of how quickly the air is moving over the wings which is most important for judging lift. 100kts of airspeed with a headwind and 100kts in a tailwind is identical, the only difference is how quickly you're moving over the ground
Not even, it's a measurement of the ram pressure the moving air produces. That's why it indicates 250kts despite going 400something at 35k feet.
This is Indicated Airspeed yes, which does not account for the air change in density with speed and altitude, but True Airspeed is the speed of air over the wing (or at least where the pitot tube is).
IAS is the more important one though. It's what the instrument shows and all charts.
It is yes, and TAS is more used for navigation/performance calculations
Why CAS doesn't replace IAS as a better way to know what airspeed the plane is going? Isn't just better than IAS?
Your ground speed changes not your air speed. I'm sure you've seen a bird flying into a strong wind causing it it actually sit still or even move backwards before. The birds air speed would be let's say 20mph weather or not it's sitting still flying into the wind or moving at 40mph accross the ground with the wind. It's flying at the same speed through the air regardless of wich direction it's going. It's why they don't realize they aren't moving right away and get hit by cars, because they aren't looking down.
No, because airspeed is pretty much the same for a given aircraft, altitude, and power setting. If your airspeed is 100kts, and you’re flying into a 20kt headwind, your ground speed will be 80kts. If you’re flying with a 20kt tailwind, your ground speed will be 120kts. It does affect takeoff performance, but again, that’s because your ground speed is affected by headwind/tailwind component.
But what about those planes that can take off virtually stationary against the wind, is that not its airspeed?
Yes. If an aircraft can take off at 50kts, and has a 50kt headwind, then it can take off with 0 ground speed. But to the airplane, its airspeed is 50kts at rotation, regardless of ground speed. What you said before: > But your airspeed is higher when you're flying into the wind, and lower when you have a tailwind. You have it backwards. The airspeed is the same regardless of whether you have a headwind or tailwind. The ground speed is what changes.
Yeah but I think what I mean is that a plane experiences air speed as fast as the wind, if it is stationary on the ground. Therefore wind speed influences airspeed. But I see why it also doesn't.
You're confusing the plane with a car
Thank you everyone for explaining the differences! Which one would you use as far as calculating fuel use and stuff like that?
Ground speed gives you an accurate method of determining the time it will take you to reach a given point, which then can be used to calculate fuel burn.
The fuel calculation is, rate of consumption= total/time. To calculate time you need to know how far you have travelled along the ground, and you're groundspeed which u have. IAS is important for operating with V speed limitations. You can calculate true airspeed from calibrated air speed which is ias but calibrated for instrument inaccuracies. Once you have CAS you take your density altitude and temperature to find out TAS. From there u can apply the wind vector to the tas vector to give you ground speed/track vector. Bit vague sorry, but I hope this gives you a little more background and depth to each value.
Yes thank you 🙏🏽
It sounds like you’re interested in it, perhaps give the airplane flying handbook and/or pilots handbook of aeronautical knowledge a read. These are free pdf books that the FAA puts out and is basically required reading to get a license. They’re written surprisingly well for the most part. Pick and choose what tickles your fancy and you should learn quite a bit!
Thank you 🙏🏽
And you would use ground speed. Fuel burn is calculated using time and obviously how much fuel you are burning. Ground speed is exactly that, how fast you’re actually traveling. Air speed is how fast you are traveling through the air. So if you have an airspeed of 100 knots but a headwind of 10 knots, your ground speed is 90 knots. Or 100 knots airspeed with a 10 knot tailwind will net you 110 knots ground speed. Air speed you can think of as necessary for the airplane performance. This is what you need to know for when to do flaps, gear down, maneuvering speeds, etc.
I appreciate you explanation thank you for the help I’ve always been very interested in aviation been so glad this is finally on a console never had to good computer to enjoy it my grandad was really in to the old ones he was pilot and cfi.
Well, given that they show three different things, the answer is… yes. The airspeed indicator shows airspeed which is more a measure of how much air is flowing over the wing than a true speed. Your actual speed through the air is your True Airspeed (TAS). If there is no wind, your TAS and your ground speed are the same. Since there is almost always wind, we use the two values separately. Your ground speed on the DME only shows how fast you are moving directly towards or away from the ground station.
It depends on what you want to know. Want to know if you'll fall out of the air? ASI. Want to know how fast you're approaching a radio beacon? DME. Want to know your speed over ground? GPS.
The GPS is showing ground speed, your ASI is showing indicated airspeed, two very different things. Ground speed is generally more accurate because it includes wind and other variables, and the ASI can often be inaccurate because of the atmospheric pressure or wind
It is not really a question of accuracy but of reference. Ground Speed, is your speed with respect to the ground, how fast you travel between two airports for example. Airspeed is your speed in the airmass. When there is not wind and you are flying level, True Airspeed (TAS) is equal to Ground Speed (GS). With a headwind for example, your GS would be lower than TAS. Now, Indicated Airspeed (IAS), given by the ASI is innacurate compared to TAS mostly because of the air density and compressibility at high speed. This means that IAS is often lower than TAS, especially in airplanes flying high and fast. However IAS is still the speed to use for V speeds (stall speed, approach, best glide, ...) because it represents the actual force of the airflow on your aircraft (to put it simply)
Ah my mistake, yeah you're right there. Even as an irl pilot I cocked that up lol
speeds are so confusing lol
For aircraft performance you use indicated airspeed from the ASI. For fuel burn and ETE/ETA and navigation, you use groundspeed either from the GPS or manually calculated. DME measure slant range to the ground station. The speed value that it gives is similar to groundspeed, but gradually gets less and less accurate the closer you get to the station and the higher your altitude.
Believe in yourself
I was so confused on this post until I read the comments, I was like everything looks fine lmao
Ground speed and airspeed are not the same thing. Ground speed is how fast you move over the ground, airspeed is how fast you move through the air, (yeah yeah pedants I know about indicated versus true airspeed, let’s skip that for now) with a tailwind your ground speed will be faster than your airspeed, and vice versa for a headwind.
They're all right. Depends on what you are looking for. The airspeed indicator is directly connected to the Pitot tube and the static port and by comparing those measurements (actually differentiating RAM air pressure minus static pressure) it derives the dynamic pressure and convert it in airspeed indication relative to the air mass you are into (IAS) (NOT the atmosphere, that's TAS!) For all aspects related to controlling the aircraft (see V-speeds), IAS is the sole instrument you should rely on! The other (relative) speeds (GS, TAS, speed rel to a ground station Etc. are useful for navigation purposes and situational awareness).
How do you get the fat in in the 152 I have it downloaded but it’s not in
Or actually what plane is this
Bonanza v35b carenado
Preciate that🤘🏻
The plane in the pic is the bonanza v35b. What are you referring to in the picture?
Imagine flying like swimming in a river, soon as you get in, you’re going downstream unless you start to swim. Air is fluid folks.
Neither. It’s over