How the Airspeed Indicator Works

[@binaz6840]

I am in ground school and yesterday class was about how the airspeed indicator works. the school was showing us photos only and it wasn't helping me. this videos is amazing I've already sent it to few of my schoolmate and they loved it. I might just take the video and give to my school so they can start using it in the future. Thank you for the video.

[@tasnimewhida2573]

amazing!! wish i had seen this video when i was still in flight school, it would have made my life so much easier but it is still very helpful

[@Ishan-l8r]

Great explanation! Please make more such videos! 👍

[@GianLucaNoia]

@@Ishan-l8r we have videos on all instruments on our channel. Also please visit passfaaexams.com for the full software where these videos are extrated from.

[@josephwhite4716]

Came here to remember why an alternate static source made airspeed indicate faster. Mission accomplished! Thanks!

[@alchemy1]

If I install one of those on the roof of my house and the wind is blowing at it at 70 miles/hr, say how fast my house is moving?

[@GianLucaNoia]

The video already explains it as the pressure inside the diaphragm and the chamber of the instrument stays the same there is also no change in the reading of the Airspeed Indicator. If your approach at the surface is 100 kts indicated at 20,000 feet it is still 100 kt indicated. You will need a longer runway as your true airspeed is actually much faster but the instrument still indicates the same and you have to use the same speed.

[@TheAdolex60]

Very good demonstration.

[@777DEHME]

is it that important to determine airports position using latitudes and altitudes?

[@heidikaiser324]

This is a great video...I wish you could talk jus a tad slower so student's brains have time to process all this great information.

[@feelinghearts89]

excellent video for student pilots to understand the concept...

[@mycomputerrocks5026]

very good explanation ............keep it up

[@josephdouglas5242]

Really liked the animations that went along with your explanation. It's not a terribly complex instrument, just very difficult to visualize for me.

[@GianLucaNoia]

Agreed. It isn't a very complex instrument, but it's probably the most important, especially when in the IFR environment In IFR, (Instrument Flight Rules, or for you who are unfamiliar with the term, when you are inside the clouds and have no reference to the outside world), The altimeter should be your primary instrument (the one you would monitor the most) regardless of the attitude. When you can't see outside, at least, make sure you are above the highest obstacle, Setting the altimeter correctly and understanding the way it works makes the difference. We pride ourselves in being the best aviation TEACHERS in the world. Helping everyone understand how the altimeter works, correlating it to everyday life, while making it all fun, was and is a top priority in accomplishing that goal.

[@chimwemwetembo9095]

Kindly do a video on the operation of the remote reading compass

[@737rambler]

My understanding is that the airspeed indicator judges the aircraft's speed by the amount of air entering through the pitot tube. What I'm slightly confused with is how this will give the correct reading of the aircraft's speed if the aircraft were to come up against a large gust of wind, this will slow the aircraft down yet the amount of air entering the pitot tube will increase. How does the airspeed indicator correct for this occurence ? Thank you for your help !

[@GianLucaNoia]

It doesn't. You have to correct for it. But it doesn't matter because the airplane is generating lift accordingly. If you encounter strong winds your groundspeed will be slower but your indicated airspeed and lift will be grater and less power will be required to stay aloft. If you encounter gusting conditions during landing as a precaution you should add 1/2 the gust component to your approach speed because if the gust stops all of a sudden, you would also lose the extra lift produced by it and that could lead to quite a hard landing.

[@casapilotsaustralia3599]

How do u find 27.92?

[@olivierboin4751]

What if just the drain hole is blocked (eg: due to insect nest)?

[@danielaristizabal5705]

The airspeed would also freeze at the current speed as the air cannot escape from the diaphragm, I believe.

[@Enrique-pi1nh]

@0:37 it says 'the altimeter and its parts'. did you mean 'the airspeed indicator and its parts'?

[@Enrique-pi1nh]

@1:07 narrator said '...how the altimeter was built,...'

[@GianLucaNoia]

Yes it should be the airspeed indicator and its parts

[@janettewilliams5444]

Great explaination, thank you very much.

[@alexlamb19]

Brother, this is a great video, full of very good information that helps me put into words the concepts Im teaching to my students. But... can you nix the voice echo that sounds like you're speaking in an empty room? Its distracting.

[@raunakdubey9321]

Why does the elevation of a place increase in winters and reduce is summers and why is QNH lower over hilly terrain?

[@GianLucaNoia]

Get the full courses at: passfaaexams.com/

[@juanriveroll6075]

really liked the video, Do you have one that explains gyros? thanks

[@GianLucaNoia]

juan riveroll Sure do. Here you go: kzbin.info/www/bejne/r2KkqpuMm7tmprM Keep in mind that these are just extracts from the full courses. For more detailed explanations take a look at our full courses at: passfaaexams.com/

[@jeanstassin768]

One thing I don't really catch : you explain that changes in pressure won't affect the IAS because the change in impact pressure in the pitot tube will be compensated by the change in static pressure in the chamber. But how than to explain that there is a difference between TAS and IAS when we climb ? The compensation doesn't occur the same way ?

[@GianLucaNoia]

TAS is IAS corrected for temperature not pressure. Pressure, again, is corrected automatically by the instrument.

[@franzrapuanobarbon5698]

Hi, for the airspeed consequences in case of flying into colder air or higher pressure, you need to fix one parameter, I mean, or you fix the TAS or the IAS. In the first case, if you fix the TAS, then flying into colder air, the IAS will increase, and in the other option, for higher pressure, if you fix the IAS, then, the TAS will be decreased, but always fixing one parameter. Changes in temperature or in pressure will always affect the air density, and therefore, the dynamic pressure, which is the one that gives us the measure of speed.

[@shockysocky5396]

Gian becareful with what you are saying about pitot and drain hole blockage at 4:10 because you said, "static port" and not "drain hole." I was confused for a minute, but later understood that you meant to say, "drain hole" there.

[@SPY_DAD]

Nooowhy would u want to determine an airport position by latitude and latitude? Where did u get this from?

[@jhc2440]

I still don't get the point of relationship between Static Port and Pitot Tube..... I got the point of how airspeed is measured by Pitot Tube... But then I saw people saying that airspeed indicator actually measures the average of speed from Pitot Tube and the one from Static Port. Is this right?

[@chrogoog9642]

+Hyeonchang Cheong Static port is showing static (still) air around airplane. Pitot is showing dynamic (moving). Airspeed indicator working "moving - still = your speed".

[@Miguel0363]

That's in fact incorrect. According to Bernoulli's principle, Total Pressure=Dynamic Pressure + Static Pressure. What the pitot tube reads is indeed the total pressure, and static port (as stated in the name) reads the static pressure. The instrument is calibrated to perform "calculations", in this case the Total Pressure from the pitot minus the Static pressure from the static port which results in the dynamic pressure, the pressure associated with speed. You can see it this way, if the dynamic pressure(speed) increases, the static pressure will decrease, vice-versa.

[@muhammedv2411]

Same doubt

[@BeyBoy17]

At 2:00 when you talk about temperature you should add an annotation to make it more clear that temp does not affect the correctness of the Air Speed Indicator ( the Vspeeds like stall speed will be the same regardless or air temperature. I understand you're just trying to show the relationship between Tas and Ias but it's slightly confusing.

[@deroalvaro9622]

Sir, can you please explain one thing again...Okay, if our airspeed depends only on temperature and not pressure, so how it works on high altitudes, where it's approximately -55C, and static pressure is low?

[@andrewdean5230]

what would happen to the airspeed indicator if the pitot and static tubes where the wrong way around when they are plunged in

[@sathishd1286]

the instrument will not work

[@singhnaveen5694]

why denser air exert more pressure on diaphagram

[@jeanstassin768]

Thanks for your answer, Gian Luca. So if I read you well, TAS will be different from IAS only because of temperature change when I climb. But, as temperature decreases with altitude, and if the speed indicator compensates for pessure changes, the decrease in temperature should make the air more dense and so the IAS should rise... But if I'm correct the TAS becomes higher than the IAS as altitude increases. How come ?

[@GianLucaNoia]

The problem is that as you increase altitude the air is less dense, not more dense because it is spread out over a larger area. This means less particles impact the pitot tube so even though the temperature is lower the IAS is also lower due to the decrease in molecules,

[@Electricutie]

I've been looking for this answer for a while! THANK YOU!!

[@seg-z5j]

Thank you for the well made video. One question, so why is the ASI connected with the static port when it reads the dynamic pressure from the pitot tube?

[@seg-z5j]

Question with how the airspeed indicator works. If the drain hole is only for to extract the water out of the pitot tube, why does the airspeed indicate a drop when the pitot tube is blocked while the drain hole is not? I'm assuming that the ram air pressure(dynamic + static) in fact does flow out through the drain hole. Am I correct?

[@GianLucaNoia]

+Karl lee pitot tube blocked drain hole open would give you Static minus Static = 0

[@sellomashiane2139]

Hi Sir please correct me if am wrong ,when flying at certain alititude e.i 1000ft at 100knots the capsule in the casing will expand due to the speed at which the aircraft is travellin at, cause it doesn't get affected by pressure.flying at same ft but at 50knots the capsule will less, causin air in the casng to me more.

[@matthew7352]

Thanks a lot, really helpful~

[@diegobruno5050]

A trick: you can watch movies on flixzone. Me and my gf have been using it for watching lots of of movies recently.

[@MrDouglasdc3]

thank u. this video helped me a lot :)

[@zhoujunyu2107]

i have a question about VSI, from the book we know when the static port block ,the VSI will show zero moment.we can break the glass of VSI in order to let the VSI work, but when the static port block, there will some pressure in the diaphragm, when we descent, the pressure will come into the VSI BOX form calibrated leak,and the high pressure will push the diaphragm which can show the descent rate. i am so confusing about this problem, can anybody teach me ?

[@GianLucaNoia]

Both the large opening in the instrument and the calibrated leak are connected to the static port so if it freezes, all freezes and descending would make no difference (instrument still reads zero). We have a video on the VSI here it is: kzbin.info/www/bejne/e4OzY6GBnLyjrs0

[@jeanstassin768]

I try to understand deeper. So the speed indicator measures the speed by différences in total pressure in the pitot tube. As total pressure is Dynamic pressure + Static pressure, and as the static pressure varies in the chamber as in the air, we can say that the indicator measures speed by dynamic pressure only (if nothing clogged). Now the dynamic pressure will depend on our speed through the air, but also as you write, on the air density. As you say, as air (and gases) expand with temperature, the density will decrease if temperature increases. This has for effect that lift will decrease on hot days (notion of density altitude) or, as another example, that warm air can content more water vapor than cold air. Right ? And also, that the speed indicator will indicate lower than the true airspeed when temperature increases, because warm air is less dense. But if density is affected by temperature, can it be also by pressure ? As we climb, TAS will be greater than IAS, because by pressure decreasing, density decreases ? Loss of temperature when we climb should increase the density, but as I understand the loss of pressure has a greater effect on density than the loss of temperature. Or do I miss something ?

[@harixav]

Jean Stassin the video says temperature variability has far an effect on airplane speed than change in pressure.

[@kilik92]

Great video!

[@mithlesh69]

you told that the reading affected when there is change in temp as the density of air changes but it is not affected when there is change in pressure as the CHAMBER IS CONNECTED TO STATIC PORT but the chamber was connected to static port when the change in temp was occuring also???

[@GianLucaNoia]

Temperature affects the density of the air. Imagine it this way: in hot temperatures less air is impacting the pitot tube so your airspeed reads lower, while in cold air more air is impacting it giving you a higher reading. Pressure changes make no difference because they are balanced by the chamber being connected to th static port,\.

[@callumclausen8658]

anyone understand Why does temp makes a difference but press not? With temp surely it's the same principle as press where the colder static air also becomes denser so won't affect it?

[@cavinson211]

why does your true airspeed increase with altitude if by your explanation it should decrease.

[@kunaldeva3620]

Can a aircraft engine remain on full power without take off on the ground?

[@rcairflr]

Yes, but the manufactujrer may have restrictions on how long the engine can remain at full power on the ground

[@basel9898]

Well Done!

[@AlexLee-in6sr]

for a change in temperature, wouldn't understand why that would effect the reading... because wouldn't the static port pull in air of the same density according to the laws of physics?

[@nandinishirsat7628]

As we go up The air gets less denser And hence it happens

[@brucewatney4416]

What causes Asi to under read by 10 knots

[@GianLucaNoia]

Well if you were flying at a very high altitude the decreased density of the air would cause the ASI to read lower. For more visit: passfaaexams.com/

[@megadavis5377]

In fifty-three years of flying I have never heard before that pressure has no effect on the airspeed indicator - that only changes in temperature have effects on it. But nowhere in the PHAK - 8083-25B does it suggest this theory. Conversely, nowhere in this manual does it suggest that temperature, by itself, has any effects on changes in indicated airspeed at all. Changing temperatures will of course affect static as well as dynamic pressures - which will, in turn, affect the airspeed indicator. But the airspeed indicator is itself a differential pressure instrument. Air does not flow through a pitot tube, it only impacts it like you're stuffing clothes in a bag. And it is a liar at all altitudes except at sea level. At all altitudes above sea level it stops indicating your actual speed through the air and indicates to you only the dynamic airspeed which the entire airplane "feels" it is encountering. That's why we need to calculate our true airspeed - so we'll know what our "true airspeed" really is... Where did you get this idea that only temperature affects the airspeed indicator? Are we missing something in this video?

[@bennysingh90]

❤❤❤❤❤thank uu sir

[@jitegemee]

I watched many air crash investigations videos , just for curiosity sakes, not a pro. I have seen thousands of crashes caused by mis- readings produced by blockage of pitot tube. My question is , isn’t there a way to tell pilot,when pitot tube gets blocked? Are there other methods of measuring speed and attitude when pitot tube blocks? What are the recent innovations? I loved this video explanation.

[@GianLucaNoia]

jitegemee The easiest way to detect a pitot blockage is to cross check all your instruments. If the airspeed keeps decreasing but the altimeter and VSI do not show a climb and neither does the attitude indicator (and you have not touched the power settings). There is a good chance that the pitot tube is becoming iced. Nearly every plane out there, definitely if Certified for IFR (flying inside the clouds), has a pitot tube heater. Turn that on and you are good to go.

[@jackjones3657]

jitegemee GPS

[@onteigening]

Thank you for sharing!

[@GianLucaNoia]

Sorry but I really can'i understand what you are asking

[@rajsingh0621]

A great video

[@rineeshsingh4811]

What will happen if only the drain hole blocked

[@GianLucaNoia]

If the drain hole is the only affected (blocked) input nothing will happen but in heavy rain the Airspeed Indicator might malfunction.

[@rineeshsingh4811]

Gian Luca Noia air which is intering in the pitot tube after accumulation in pitot pressure chamber it apply pr in instrument where it goes

[@GianLucaNoia]

???

[@rineeshsingh4811]

Gian Luca Noia if something enters in a chamber it need a way to come out

[@rineeshsingh4811]

Gian Luca Noia What is the use of drain valve in pitot tube

[@LuisHernandez-kw6rt]

great vid.

[@davidwallace5738]

Thank you

[@salimkumar9748]

Thanks

[@mikeearls126]

The altimiter does not use ram air

[@GianLucaNoia]

This is an Airspeed indicator!!!

[@mikeearls126]

@@GianLucaNoia I am just saying it because you say "altimeter" in the beginning and it says "altimeter" on the top of the slide. I think if these things were changed, it would be less confusing for those watching...that's all man, you dont have to get mad about it

[@iosef3337]

The idea that i have can solve the snow problem.

[@alchemy1]

Isn't the simplest way is GPS system, Just hook up to satellite and be done with it already. No?

[@Flyinverted]

Excellent video ! Thank you so much for this Is it possible to make a video of cabin pressurization? Please :)

[@saeidahmadi942]

i dont understand!!! , your title is about airspeed indicator but you are explaining about altimeter?! and of course airspeed depends on air pressure

[@santhoshsandy7941]

Aneroid and diaphragm are same

[@davidliu2243]

So the airspeed indicator would show a speed close to 0 when the plane is stalling? xD

[@GianLucaNoia]

An airplane stalls when the critical angle of attack is exceeded regardless of your airspeed!

[@davidliu2243]

Gian Luca Noia yeah. So when the plane is stalling, what would the airspeed indicator say? Let’s say it’s lost all forward action and just falling 😂

[@GianLucaNoia]

@@davidliu2243 It could say 10Kts or 500Kts. Airplanes don't just fall. A stall is simply a loss of lift but the plane still moves forward.

[@abinboban3316]

Types of drag...

[@rcairflr]

What is being shown in this video is old technology and not realistic for modern air data systems

[@GianLucaNoia]

Keep in mind that the purpose of most of these videos is to help Pilots working on their Private license and/or Instrument rating. Be it for cost, aircraft availability, etc, the majority of students prefer to accomplish their training in older airplanes still equipped with analog instruments rather than glass cockpit. Also Airspeed Indicator questions on all of the FAA Knowledge Exams still focus on these analog instruments!

[@rcairflr]

@@GianLucaNoia > I can understand that, but in the real world most of us work on or support modern aircraft in some capacity whether it be engineering or customer support etc. You will not see this unless you work on old general aviation aircraft. I just don't want people here to assume they are getting into aviation and will see this as modern technology. It is old antiquated technology.

[@GianLucaNoia]

@@rcairflr Agreed, but this video is for the Primary students. It is an extract from our Private Pilot Interactive Test Prep Software which focuses on helping students pass their PPL Written through understanding rather than memorizing questions and answers. We do offer advanced IFR training software (our IFR Procedures App) where we cover advanced systems and glass!

[@daanzieren2948]

you sound like Tom Hanks

[@dphorgan]

Daan Zieren No the Doctor from Star Trek Enterprise.