Types of Airspeed, Explained

When you're moving an object through a moving air mass of varying density and temperature, and using that air mass + speed to keep the airplane in the sky, its important to know about more than one type of speed. Learn about them all here. Subscribe for new lessons and pilot training videos.
Groundspeed (GS): Speed of the aircraft over the ground
True Airspeed (TAS): Speed of the aircraft past the air
Indicated Airpseed (IAS): Measured speed of the aircraft through the air
Calibrated Airspeed (CAS): IAS corrected for pitot tube position error
Mach Number: TAS/Speed of sound

[@gregagee4328]

After 7 months of studying to get my private and now in instrument training, I finally understand True Airspeed!!! I could never get an understandable explanation for it, and you got it through my hard head!! Thx!!

[@LearnToFlyWithPilotGuy]

Very well done! I'm going to share this video with some of my students.

[@luislepe5026]

So what is the speed indicator is it used throughout the flight?

[@patrickfain9318]

Best explanation I have found on the different airspeeds! I can actually understand them now thanks to this video! Thank you

[@stormapex2122]

out of all the videos and descriptions ive seen and read,this one is the best. This one makes me truly understand the differences between TAS and IAS. Thank you for this video.,

[@michaeljohn8905]

Thanks this was very good.I have been flying a long time and this is one of the best descriptions of airspeeds that I have ever seen. Thank you for your hard work.

[@samuel-jq9wl]

I don’t know who disliked this video because this is the best description of airspeed so.

[@stephenfraser2521]

Trolls and Turds

[@gogogeedus]

@@stephenfraser2521you dont add the 20kts head wind to the TAS you subtract it from the ground speed, with the head wind your TAS will remain at 200kts and your ground speed will be reduced to 180kts, that is why you have dislikes, it should be 22k dislikes, its a good example of mass delirium!

[@gogogeedus]

@@stephenfraser2521 Turd

[@stephenfraser2521]

@@gogogeedus NOUN vulgar slang a lump of excrement. a person regarded as obnoxious or contemptible.

[@ifoother]

Excellent explanation! it will be great to add a video explaining the density/pressure :)

[@FriousBlackPanther]

Great video! Thank you for the excellent explanation!

[@mjhancock6029]

You should've kept TAS the same when talking about GS. If the plane's flying at 200mph and there's a 20mph headwind, the TAS is still 200mph, not 220mph. Only GS is affected by the wind. Like running on a treadmill. Your running speed for instance is 10mph, and the treadmill (headwind in this case) is also 10mph but you're still running the same speed.

[@gogogeedus]

Only a couple of people have notice that fact,I don't know why!

[@grasuh]

@@gogogeedus The video is not wrong. It is all matter of PERSPECTIVE. TAS is the speed of aircraft RELATIVE to air molecule. In other words, starting with no wind, GS=TAS, With head wind, if TAS is to stay the same, GS should go down. With head wind, if GS is to stay the same, TAS should go up. With tail wind, if TAS is to stay the same, GS should go up. With tail wind, if GS is to stay the same, TAS should go down.

[@grasuh]

Your interpretation is based on the pilot's frame of reference. However, the video uses the ground as the frame of reference. That's why it says GS is not affected by the wind. With 20mph headwind, to maintain the same GS, the TAS should increase to 220mph.

[@gogogeedus]

@@grasuh the video is wrong,the TAS will be 200mph,to suggest otherwise is to suggest that two aeroplanes traveling toward each other,one with 20mph tail wind and the other with a 20mph headwind would be travelling the same speed relative to the ground, but the reality is one would arrive at the observer on the ground sooner,and that plane would be the one with the tail wind. the reason why the plane going down wind is faster is because it has the tail wind added to its speed,so the true air speed stays the same but it's ground speed is increased by 20mph. hence the plane with the greatest ground speed 220 will arrive at the observer before the plane with the headwind.

[@grasuh]

@@gogogeedus Both you and the video are correct. You are arguing with TAS FIXED, the GS should vary depending on wind. The video is arguing with GS FIXED, the TAS should vary depending on wind. They are both correct statements!

[@matthewlaslop9907]

Thanks for simplifying some of these concepts! Great video!

[@kingkora9538]

Just awesome 😍 keep up the good work. Thanks also

[@ericmcgrew8952]

This is the best explanation of the different sounds that I have ever heard or read. Thank you!

[@riderepublic7260]

Best video so far on KZbin that I've found to answer these questions!

[@samaksh_12]

agreed

[@vaivaged]

This is amazing. So well explained, love the illustration.

[@MH-ve5sz]

I love your video! Can you help me with a concept that I've been struggling to grasp? How is airspeed affected by an aft cg? With less downforce from the tail, and less drag, I believe your true airspeed would be higher. But how would your indicated be affected? Would it also be greater? If my indicated were 100kts with a middle cg, and then we took the exact same conditions, but had an aft cg, would my indicated then be 110kts for instance? Thanks!!

[@CaptainMav]

I explained it this way to a 30 year 737 training captain and he said he loves the analogy. Imagine you’re in a speed boat on a lake, with two passengers. If they were sat at the rear of the boat you’d achieve the boats maximum performance, where as if they sat right at the front the boat would struggle to achieve that slightly positive angle of attack and hence the boat would be slower and therefore less efficient. I hope this helps

[@Manish-jb4uy]

Concepts are explained in very understandable way. Hope we get more topics covered.

[@Eddie-zo5fr]

The best explanation I have found. Good job

[@fatihaltintop]

Very clear explenations, thank you so much

[@RW22]

Great video I love your explanation Thanks

[@senomuzaeni4658]

I really loves your explanation sir, please do another one on air temperatures measurement such as tat, sat, oat, and so on.

[@theodore388]

Thank very much ! Very clearly put into words and illustrated. I do have one question: as the speed of sound is a function of temperature, on a cold day at a ground level, will the speed of sound be lower than it would be at that some location at ground level but on a warmer day? In other words, can the speed of sound vary at ground level?

[@itellyouforfree7238]

Yes it can: en.wikipedia.org/wiki/Speed_of_sound#Practical_application_to_air

[@patriotpro6891]

Thank you, for the thorough explanation!

[@AMentorway4u]

Well done. Love the presentation.

[@cheesebalz100]

Hi excellent video , can I use a part of this video in my channel. Planning to fly ceiling limit on airplane and use this to explain. Will give credit and provide link to this video in the description.

[@VS-jl1zw]

Thank you! It really simplified the topic

[@mechnitin]

an amazing oversimplification, well done

[@shubrudubc]

Great explanation! Thanks!

[@TomTom-jv5sv]

Well explained! Good job

[@dantoylamb1136]

Perfect! I love this presentation.

[@akovaler]

Brilliant explanation! Thanks a lot!!!

[@leopoldoorozco6518]

types of Airspeed very well explained

[@00492663968482]

great video!!! Could not have been explained better!!

[@NickWindham]

Really good video on this.

[@thomaselser8786]

Easy to understand. Well done.

[@jamespilot93]

Great! Very clear explanation.

[@aramelmi1020]

Very clear explanation Thank you!

[@mikhailhunter5277]

Amazing explanation man!

[@mohammedzulk8485]

For a commercial passenger aircraft in the event of pitot static system failure, then even just knowing the ground speed &altitude from say satellite 🛰 communications wifi would still allow the pilot fly the aircraft. Correct?

[@chalitha22]

Excellent explanation!

[@user-cs9jc5id8r]

why in flight manual cas and eas are given as ias

[@Labolas2Glasya]

Amazing, now i understand the new flightsim a bit better :)

[@tortuegeniale5878]

This video helped me a lot THANK YOU!!!

[@itsharshjain]

Very well explained. Thanks👍

[@chrisluehmann3094]

Fantastic video.

[@NoName-jl7gs]

Thank you very much for this great video! Best regards from germany!

[@gogogeedus]

Get with the program Fritz! I wonder why you lost the war!

[@jeremylingen6565]

Best explanation!

[@maldinduwijayarathna9486]

thanks for this great explanation vector pilot prep.

[@chalitha22]

Excellent video! 👍💪

[@timdouglas2011]

OMG! This is an amazing explanation!

[@gogogeedus]

except for the fact that it's wrong!

[@updatedotexe]

@@gogogeedus ok boomer

[@miguelfernandes657]

Very good video, thanks!

[@evanotter7149]

Great job 👌

[@helmutbraun7112]

Excellent explanation, do make video on Wind deviation and corrections. Thanks 😊 in advance 👍

[@j_1mmy175]

Thanks for this video really helpful.

[@M7RAA]

thanks, this was great

[@Rombbb]

Am a new to this so correct me if wrong, but I think what would help is to start with why speed outcomes can be different to the old car speedo in the first place. Car uses wheel rotation on ground, plane uses differences in air pressure to calculate speed. Air speed simply must be measured differently because there is no contact with the ground, which gives different results because air is subject to density influences like altitude, temperature and humidity which affect the outcome of the air speed measuring method. 2:33 is a bit confusing as slowing down from head wind applies to a car on the ground as well so doesn't seem a differentiating factor. The difference is in the way of measuring, one of which uses air and is more subject to its influences, the other not.

[@gogogeedus]

Someone in the comments used the simple analogy of putting the car on a treadmill to understand how a plane acts in a headwind, if the treadmill has a speed you can subtract that number from the forward motion of the car in relation to the ground.

[@Rombbb]

@@gogogeedus Good insight, thanks !

[@abdullahalsadani8875]

Very useful video! Thx

[@dew9103]

This is an amazing video

[@yveskrieckemans]

Indeed, great explanation. But it doesn't why TAS is said NOT to be affected prevailing wind. Could you explain? Because the video definatly shows an increase in TAS when there is a headwind.

[@ryanveyr9195]

I'm extremely confused now

[@FRANK-co1dy]

In fact: GS=TAS+wind. if we have a headwind then, windTAS if we have a tailwind, then wind>0 so GS

[@FRANK-co1dy]

@@ryanveyr9195 don't be confused bro. See my explanation below

[@jacobjasch4397]

A very helpful way to think about it is by using the example of a travelator at an airport. The travelator is the air, you're the aircraft. Its moving in one direction.. if you jump on and run with it you are moving at the speed you're running + the speed the travelator is moving. So if you started a foot race with a friend who ran next to the travelator you would go faster as your running on a moving surface (assuming he's not Usain bolt). If you run against it, your moving over the ground at the speed you're running minus the speed of the travelator.

[@gogogeedus]

That is right, I mean to say you should be confused because the TAS should stay the same and only the ground speed should change, the animation is confusing as well, the planes should be traveling at different speeds to make it easier to understand what is happening in relation to their ground speed.

[@sameeransari7359]

Nicely explained 👍👍

[@faraha.b7603]

Well explained.

[@lumberjackcharlie6154]

So the higher you are the thinner the are so the higher your gs stall speed is right?

[@rajibkudas123]

So well explained...

[@aviator_nic2043]

Just a question at 2:01 wouldn’t Ground speed be 180 as aren’t you basically slowing the plane by 20 knots?

[@kineticU]

Excellent. Thanks

[@ivusgeorge8314]

Great video

[@oudomvicheakouch4795]

Hello, Sir, I have a question. Is it possible to know the speed of the aircraft if we only know the distance and time that the aircraft will be arriving? Since my problem did not mention other conditions, can I just the formula V=d/t?

[@siddarthr3345]

If the distance d is the actual path covered by aircraft on air and time t is the time of cruise flight , you might get an approximate speed.(which mostly isnt the real speed ) "if the aircraft follows a straight path"

[@chandimalfernando1839]

Very good explanation..........

[@iforgotmyusername0]

very good explanation

[@sinisamandaric]

Good job except TAS is how fast you actually move through space. The closer to the ground you are, TAS is closer to IAS. The higher you are, the air molecules are more far apart and you move faster through that space. So your IAS may be the same at 5000ft and 2 10000ft but TAS will be higher at higher altitude. Also take in consideration temp.

[@jacobjasch4397]

The reason TAS and IAS are closer together at lower altitudes is to do with IAS not TAS though. So, IAS isn't really a speed at all, its a measure of aircraft performance, or to put it another way it is a measure of the dynamic pressure of the air on the aircraft. Temperature, pressure, density, they all decrease with an increase in altitude - therefore to maintain the same IAS at a higher altitude (i.e to maintain the same dynamic pressure) you need to go faster through the air (TAS increases) to get the same amount of dynamic pressure. The lower you are, the higher the temp, pressure, density is and therefore you can fly slower (decreased TAS) to get the same dynamic pressure over the wings. So I am not sure its helpful to classify TAS as through space.

[@ausboy9251]

Thank you 👍

[@weerdwizzord5184]

Isn't the speed of sound more effected by the medium density than by the same medium's temperature. I mean, I know temperature effects density, but I don't think it's enough to effect the speed of sound that much, right?

[@davidbrohede]

Thanks!

[@viperforty8450]

Thanks for explanation, it actually could be somewhat shorter, but the video has to be liked.

[@Runmikerun1onTube]

Viper Forty Your attention span speed is slower then your processing speed.

[@arzanbailiff7499]

Wish I had found this video earlier!!

[@enkisumerian]

Great

[@paulmorrisette1581]

Thank you.

[@TheOndrayTV]

Now I understand the relation between Mach and TAS, you sir explained it very well! Thank you very much!

[@dronerealtypl2950]

but in real plane you fly Indicated/Mach xd no one is looking for tas DURING CLIMB DESCENT

[@TheOndrayTV]

@@dronerealtypl2950 Nope, we do need TAS. As a matter of fact its used by our IRS to compute the direction and speed of the wind...

[@dronerealtypl2950]

@@TheOndrayTV so it's used by IRS, but as a pilot you don't use it. Did you ever fly cons TAS me never.

[@TheOndrayTV]

@@dronerealtypl2950 what kind of aircraft do you fly? lol its always there on our ND

[@TheOndrayTV]

@@dronerealtypl2950 TAS is useful whenever we fly, without TAS we won't know the wind direction and speed. Without TAS we will have one less sign to encounter windshear... And the list goes on...

[@onethousandtwonortheast8848]

Thanks. By the way, why does sound travel slower in cold air? This just isn’t intuitive to me.

[@pilot4807]

03:50 isn’t that wrong though? As the airspeed indicator is connected to the static port as well the pressure inside the chamber changes with the increase in altitude. Therefore, the airspeed indicator is only sensitive to changes in temperature but not to changes in altitude.

[@egamez1]

Great video but I'm a little confused. If the airspeed indicator uses pitot and static pressure, why is the IAS reduced at higher altitudes due to pressure? Isn't the static pressure reading takes care of it? What about air temperature at higher altitudes? Is temperature taken into consideration for the IAS? Thanks :)

[@airsofter22]

Also curious about this. It was my understanding that the pitot static system should take ram air + static pressure then subtract the static pressure to read airspeed.

[@itellyouforfree7238]

@@airsofter22 the pitot tube computes the pressure difference as you described, but to get the speed it needs to divide by the density (ses en.wikipedia.org/wiki/Pitot_tube#Theory_of_operation), which varies with altitude

[@billrussell4832]

Late comment but the reasoning for this why our IAS is still reduced despite it being operated by both the pitot tube and static port is because there’s less air pressure and molecules going through both the static line and pitot tube so regardless it will measure that air pressure differential which will be indicated lower due to less molecules and lower air pressure. Temperature is not really taken into consideration because what we care about is how many air molecules is entering the pitot tube and static line. So if anything the density altitude would be important as if the air is less dense there would be less air molecules and air pressure. Hope that helps.

[@saarsofer3531]

Got my thumbs up!

[@pamirplays]

thanks, i get it now :)

[@vishnuvithala6902]

The best way to think about this is ground speed is how fast the aircraft is going when you look up and see the aircraft. But what we can't see from the ground is speed at which wind is blowing.. Sometimes you look up and see aircraft going really slow and you wonder how it is staying up in air. what you probably are not seeing is a strong headwind which you need to add to the ground speed to get true air speed. Lift is based on true air speed and not ground speed.

[@BezawadaAbbayi_]

By far the best explanation buddy

[@jeffterrozas8111]

Fantastic

[@mojojojo3852]

Does the speed and direction of the wind affect the true airspeed?

[@MalfosRanger]

The speed and direction of wind would affect ground speed, which can be thought of as true airspeed plus or minus wind. As TAS is speed relative the the air mass that the aircraft is within, a headwind or tailwind does not change the TAS. Picture a swimmer in a river. Whether they swim with or against the current, their speed relative to the water would be the same although to observer on the shore they would appear to be moving faster or slower respectively.

[@pilottadeus3748]

If the static pressure decreases with altitude too, shouldn't the airspeed remain the same? Because the difference between static and total pressure musst be the same.

[@EagleFlight2007]

@1:55 Why doesn’t groundspeed decrease in a headwind?

[@drummonkeystuffuk1875]

@JM Manalo whats confusing is that planes fly higher for better engine efficiency - but generally engine require denser air to produce more power! this is why n/a cars lose power when in higher altitudes/mountains! i dont think planes fly as high as we think lol.

[@thomascunningham9382]

Minute 1:55 isn’t a great example. For a constant IAS adding a headwind does NOT affect TAS. It only affects ground speed. He should have kept TAS at 200 and changed the ground speed. The fact that TAS doesn’t change with a headwind is why rate of climb (ROC) isn’t affected by wind. ROC = TAS*sin(flight path angle). If TAS did change with wind then so would ROC which we know doesn’t happen. Wind only affects your angle of climb because ground speed changes.

[@jamesoshea3931]

​@@thomascunningham9382 Exactly. I thought the same thing immediately as well. I'm going to do my check ride in 3 days and was reviewing air speeds and caught that too 'wait a minute, the TAS wouldn't have went up. The TAS is the same for a given power setting. The TAS would have stayed the same but the GS would have reduced by 20 Knots.

[@cheesebalz100]

It does decrease , TAS is 220 and GS is 200 for headwind of 20 kt

[@gogogeedus]

@JM Manalo The TAS is IAS,the only difference being related to pressure, TAS and IAS are not effected by wind at altitude, the wind does not effect flight or push on the aircraft from any direction, an aircraft is like a balloon floating in a frame of reference,of course an aeroplane needs airspeed to fly and that remains the same, have you ever notice that people in a balloon are not effect by the wind, and that the flame on the hot air balloon is not being pushed in any direction by the wind, it is the same for an aeroplane but the only difference being the airspeed or TAS required to keep the aeroplane in the sky, when you hear someone say the wind pushes an aeroplane that person is making an incorrect statement.

[@firdavsdavlatov1685]

Awesome)

[@onemorething100]

Wow. I actually understood something.

[@gogogeedus]

Well I think it was Fienman that said something like, if you think you understand physics ,then you probably don't.

[@lucywucyyy]

is ground speed your speed across the ground or your speed relative to the ground? if i was diving exactly down at 200kts tas would my ground speed be 0 or 200?

[@flymakena]

No,speeds are in level flight...

[@lucywucyyy]

@@flymakena so it would be 0 then?

[@beezalbub7325]

Speeds are NOT in level flight, if you are in a climb or decent with movement across the ground you have a ground speed. Your question in its most basic sense, your ground speed would be zero.

[@lucywucyyy]

@@beezalbub7325 ok cool

[@gogogeedus]

There is a term that a lot of pilots use called 'relative wind' which refers to the airflow facing the aeroplane or the airflow the aeroplane is traveling through, I don't like this term as wind does not effect an aeroplane, instead I call it the air-stream, so if you attached a streamer or string to the wing the air-stream would be visible. the air-stream corresponds to the direction of the aircraft in co-ordinated flight and not its relationship to the horizon or ground. there for it does not correspond to ground speed which has horizontal axis.

[@mrmost4960]

awesome

[@aviator_nic2043]

So if I’m flying at 200 knots and my headwind is 20 Knots, am I right in saying TAS: 220 and GS: 180?

[@Agent0range67]

Yes!

[@BichaelStevens]

So, if I have to travel 1000km in a plane, which speed should be used to calculate travel time?

[@siddarthr3345]

Ground speed , just like the speed indicated on a car .

[@mustafanav6970]

Thanks

[@aleksandrnestrato]

7:34 Wow! So it's not a question of density? I mean the more dense is matter the sound travels through, the higher is its speed. Thus the fastest sound speed is through hard materials, then trough liquids, and then-the slowest-through gas. The lower is the air pressure, the further those molecules are from each other, the farther they have to travel to hit other molecules to conduct that sound wave. Another rule is-the colder the denser. Example: density altitude. So the colder the air, the faster sound travels trough it.

[@sandeepvictor6879]

Hi sir if mach speed is 0.78 & OAT is -28*c @ FL 240, then magnetic course of plane is 260* True wind 280*, mag variation 11*E, magnetic wind 269*, Wind speed 50 kts, Distance of leg 93.3 nm. So what's the true airspeed, Ground speed, & time of the leg *How to do with manual calculation without CX-3?

[@BichaelStevens]

Do your homework yourself, your teacher will be disappointed in you if you make others do it.

[@sandeepvictor6879]

@@BichaelStevens Yes Sir i did home work, Now my manual calculation and CX-3 answer are same, I got the answer

[@lazarmilenkovic8757]

bravo

[@zhanovzhan4029]

That was gooood

[@gogogeedus]

really!

[@MuhammadAli-bo5et]

Will you give me your presentation link?

[@MrCed0802]

Could someone explain why with a head wind our TAS actually increases? I would think the contrary, the wind is aginst us so our speed should decrease of 20. Thanks a lot

[@samjacobs4769]

Cedric 0802 Think about it this way. More air flowing towards you, that makes your TAS read higher, but youre ground speed is still 200

[@MrCed0802]

@@samjacobs4769 thanks a lot Sam fornyour answer. I think I get it now ;)

[@leopoldoorozco6518]

it is easy to understand. a car speed indicator gets its speed measurement by the wheels rolling on ground. on the other hand, an airplane speed indicator gets its speed measurement by the air pressure applied via tube pitot, the more pressure applied, the more speed displayed. to make it even clearer...If a plane is traveling at true 90 mph but the head wind is 10 mph that will apply more air pressure to the pitot tube adding more mph giving a false speed reading.

[@MrCed0802]

@@leopoldoorozco6518 Thanks a lot for taking the time to get back to me. However I thought it was the only IAS captured by the pitot?

[@leopoldoorozco6518]

@@MrCed0802 Yes, the pitot tube is the only source to funnel the air to the speed indicator mechanism. also, it is used by other instruments such as: altimeter, vertical speed indicator etc. going back to air speed instrument, its accuracy is afected by altitud, barometric pressure, air temperature etc. to me... when comes to an airplane such as true speed doesn,t exist but calculated speed, hence you have to recalibrate altimeter/barometer before every take off.