How does an ALTIMETER work? Explained by CAPTAIN JOE

[@martialandforbearance]

I've missed this type of technical lecture videos from you, glad to see you're doing them again :)

[@flywithcaptainjoe]

More to come!

[@tingwan8696]

@@flywithcaptainjoeStill waiting for Flaps series episode 2&3 😊

[@established_on_the_run]

@@tingwan8696I think we’re waiting for the 3rd ILS video, too! 😁

[@established_on_the_run]

@@flywithcaptainjoe Awesome, glad to hear! These were the types of videos that got me hooked years ago!

[@markjarrett9400]

I am not a pilot, I have never wanted to be a pilot, but I do enjoy your technical videos. Thank you for posting

[@flywithcaptainjoe]

Glad to hear that!

[@lanceholland9851]

I remember Altimetry from PPL days it even pops up in Meteorology to instruments and radio aids. It gets dealt with throughout up to ATPL level it is very important if it gets repeated that much. Was hard to comprehend at first, but if you work with it daily, it becomes easy in practice. Even airline interviews like to question altimeter knowledge. It is definitely a topic that needs to be well understood. A lot of things we learn in aviation are not relevant at all times, but this is one topic we use every single flight.

[@garrusvakarian3473]

I remember finding this channel when you were still at AirBerlin out of a casual curiosity for things like “what’s that thing on the wing?” Now I’m a PPL student and my CFI recommended some of your vids, thanks for starting my interest in aviation!

[@bashgaming591]

Super helpful video, as a 13 year old who wants to become a pilot and didnt fully understand the altimeter and air pressure. I now have a much better understanding!

[@flywithcaptainjoe]

Glad it helped!

[@bashgaming591]

@@flywithcaptainjoe Thank you!

[@Maxlovesplanes]

I'm also 13, been watching Captain Joe since 10

[@smithy280663]

great video..........I'm 61 and a Paramedic for 37 years.............when I grow up I'm going to be a pilot.......... ;)

[@zachrome91]

I’m from Kilimanjaro, Tanzania and I approve of this video. 🇹🇿👍🏽

[@deepakmahimkar2005]

Deepest thanks Capt. You and your videos are the reason, are what have inspired me to become a pilot. Currently am clearing my CPL papers, have cleared Tech Gen and Speci and am going to give NAV this time around. Couldn't have had a better timing for dropping this video, before this was just studding and watching your video on Mass& Balance (Fuel) and VOR. Thank you sooo much for making such amazing in depth videos, was truly missing them . Hoping to meet with u in person one day, hopefully very soon. 🙂

[@jonathanhernandez4304]

Captain Joe, These videos on IAS, EAS, TAS, Altimeter and more are great. Gives us a review and interested passengers a better knowledge of what pilots deal with. Informed passengers vote better, and will understand the needs for Commercial pilots and Air Traffic Controllers. It will also keep people from ever wanting fully automated pilotless aircraft.

[@gdm413229]

Joe, are you planning to cover the other pitot-static instruments like the vertical speed indicator and airspeed indicator?

[@flywithcaptainjoe]

Yes absolutely 👍🏻

[@Masterdude246]

Hey captain Joe good to see you uploading again you should keep uploading I newly got MSFS recently and really miss watching your old videos a long long time ago you should really keep uploading hope to see more bye bye 👋 😊

[@flywithcaptainjoe]

Will do

[@TheflyingBrit]

In response to your question at 9:00 the altimeter would show you at a positive altitude since when you hit zero if you go below that it will show (depending on the QFE )as 900 feet since it doesn’t have a negative feature also thanks you so much Joe for the vid I’ve just started my ppl so thank you for additional knowledge have a good one ❤

[@mytech6779]

It would show 99,900 feet or 9,900 feet depending on the altimeter, which for any sane person would be interpreted as -100. I have never seen an altimeter with a range of 1000 feet. However with a 10,000 range altimeter while in mountainous countries it would be possible to fly from an airport at 5000 feet elevation to a sea level airport and the altimeter would again show 5000. However a differential this large would be very noticeable to any pilot who just spent 10 minutes descending and watched the altimeter dropping to zero and continuing below; especially with the most rudimentary pre-flight planning. Anyway, I am in the USA where QFE is never even talked about, let alone used. I don't even know if the mechanical altimeters have enough adjustment range for airports at 5000 feet elevation.

[@TheflyingBrit]

@@mytech6779 sorry if I got it wrong in the uk we get notified on the QFE however it is hardly used and another thing is that I’ve only just started my PPL so thanks for the extra knowledge have a good one

[@mytech6779]

@@TheflyingBrit The UK does not have high elevations so QFE is a reasonable shortcut to avoid noting the airport elevation.

[@NikolaiUA]

Now to demonstrate a grasp of the concept I guess it is enough to say that the altitude shown would be negative. To say what the altimeter will show exactly (like 99,900) takes a specific and practical knowledge of the exact workings of a given instrument. If you're in a glass cockpit I guess it would show a negative value.

[@Arafat_Jabir]

Am listening from Tanzania 🇹🇿 Welcome to my country for numerous landscapes and a variety touristic attractions. 7:06 I'm the next pilot thanks captain joe for useful content.

[@saintbenedictscholacantorum]

Fantastic explanation - I do not fly a plane, but this totally explains why my Garmin watch always reads the wrong altitude when I go hiking. :)

[@p.s.224]

Sehr verständlich erklärt, Danke und weiter so!

[@hpramina1]

Thanks for sharing/explaining/presentation. Great review. Haven’t reviewed this in years so now I feel refreshed and will keep in mind to check a reset the altimeter settings as appropriate.

[@PeterEdin]

I'm looking forward to (and hoping there will be) a video of the related ASI 😀

[@ArestorBorges]

Congratulations Captain Joe. What a great class you're giving. I see you have come a long way since those days in training around Fort Pierce, Vero Beach. Well. You have a great day, until next time.

[@flywithcaptainjoe]

Thank you very much!

[@BernardoLizcano]

Exellent video about the altimeter. Well and clearly explained. A lot to learn!

[@flywithcaptainjoe]

Glad it was helpful!

[@chesterwang3070]

8:52: A negative value as "0 ft" was set at a higher altitude and thus lower pressure, so descending below that altitude would yield a negative value

[@mytech6779]

It is a pedantic trick question. The altimeter will show a positive value such as 99,900 due to roll over[ aka underflow ]. Visually any reasonable person will see it as 100 feet below zero, especially in the context of planning and executing an actual flight. But bureaucrats see themselves as clever.

[@Cars-N-Jets]

It's a great day when Captain Joe uploads :)

[@Ajajambo]

I really enjoyed this topic as I am weather enthusiat and tend to keep an eye on the barometeric pressure all the time. I even log the cabin pressure on my Garmin on most flights and compare how each plane compares based on age and model. Cheers.

[@isaacchee8616]

Please produce more of this kind of videos ❤❤❤

[@vsabadazh]

Yeah buddy! I am now preparing for my written PPL exams in Cyprus, and here we've got a special question in Air Law, about the transition altitude specifically in this country (which is 9000ft). I don't know if this is a common practice in EASA countries, but that's what we have here.

[@mytech6779]

The transition altitude is different for each country based mostly on height of mountains. EASA and FAA both ask this question. 18,000 feet in the USA, and our transition layer buffer is never less than 1000 feet thick, so FL190 can only be used at barometric conditions above standard pressure. 18,000 feet is also our upper limit for visual flight rules unless flying no more than 2,500 above ground level. (We have 6 mountains high enough for this rule.)

[@sebassie25]

Yeah buddy! Thanks for this great explanation of the altimeter, now I understand how, when and why standard is used 🙂🙂

[@PeterEdin]

Im looking forward too (and hoping there will be) a video explaining the related ASI 😄

[@Schla-Gulp]

Danke, ich habe jetzt endlich mal das QNH verstanden. Ich würde mich freuen wenn du mal etwas über das Wetter machen würdest. CAVOK ... NOSIG usw. Gerade die Informationen zum Wetter sind ja extrem wichtig.

[@The_Magic_of_Zelda]

Yeah buddy! Best explanation of the altimeter.

[@flightsimexplain5026]

Captain Joe, thanks for the awsome video we used it today in our science class. Could you possibly make a video that goes in depth on how ETOPS works and why it's used.

[@Phil787-9]

Great video as always, Joe! Watched the entire video in the anticipation of a section on inches of mercury (in.Hg), but unfortunately it was not covered 😥. Maybe next time then. Best regards from New Zealand!

[@flywithcaptainjoe]

Inches of mercury is the same, it’s just a different unit of measurement

[@starroger]

I'm retired US ATC. As you mentioned in the USA flight levels begin at 18,000 feet. This is dependent on the local altimeter setting (in Hg) not being 28.92 in Hg or lower. If the local air pressure is lower than that, FL180 is not used. Flight levels then begin at 19,000 feet. This is to avoid a loss of separation, because at 28.92 in Hg, FL180 and 17,000 ar the same real altitude or height above sea level. In extreme low pressure areas, tropical depressions for example, if the altimeter setting drops to 27.92 in Hg or lower, flight levels start at 20,000 feet. 17,000 to 18,000 feet are not used. This is very rare and I've only seen it once in my career. However, flyer beware. The climate is changing. In different countries in the world, flight levels start at lower altitudes. I'm sure that similar rules apply there. I leave it to you to convert inches of Hg to millibars (h Pa).

[@PhilippusCesena]

Great explanation!! Thank you!

[@aj_w24]

8:55 I can give 2 similar answer but i know only the first one will be considered right in the exam cus the sceind one is just logic and has nothing to do with pressure (I haven't given it yet, so correct me if im wrong) 1. A negative value because pressure is inversely proportional to height and since pressure is higher at a lower elevation, the reading should be lower (than the airport you departed from). Since the airport yiu departed from was at an elevation of 0 ft (as per QFE), value will decrease which means the altimeter will now show a negative reading. 2. Talking with respect to elevation as the reference frame, the airport from which the plane had departed was at an elevation of 0 ft (as per QFE) and going below the reference line (towards the ground) should result in a negative value. Overall, my answer is negative reading (in the sense, that the needle would point beyond 0 and since there's no negative numbers on the scale, it will show one of the maximum positive values on the scale) Reading= Max possible value on the scale - difference in elevation of the two airports Am i correct? (this is my own answer, not copied🙂)

[@djwarren5081]

I learn more from a short Captain Joe video than I did during a whole day at school.

[@flywithcaptainjoe]

Well that’s a compliment 😌

[@netassekaffee6682]

😂 just (perfect) in time. I have my BZF1 exam just next week and of course QNH, FL etc. are part of it. thanks for the additional prep work and please keep posting more PPL topics

[@netassekaffee6682]

Mission accomplished 🤩 now ICAO language proficiency test and I believe you have a clip for this as well. thanks again

[@FernandoNuno100]

Now, I know the difference between transition altitude and transition level. Thank you

[@PLANESHENRITRAINS]

fantastic video, thanks joe! Answer to the question: On departure QFE setting, the altitude will be negative at a lower arrival airfield, so an analog altimeter should show 0 as soon as the aircraft passes the departure airfield altitude (or pressure layer)

[@leonvanderlinde5580]

Now I understand why a Vickers Vicount of SAA (Rietbok) accident happened. The pilot apparantly did not correctly set his QNH level at the previous airport and smashed into the sea in bad visible conditions. Thanks.

[@joachimbayon6463]

Unfortunately, it is not the only one. Recently, 1 or 2 years ago, an airliner entered a wrong qnh. It almost crashed.... the gpws saved them

[@frankmckenzie8981]

clear video and explanation Joe, why there is no automatically integrated system so that as a pilot you do not always have to adjust the QNH? Thanks for your answer and great vids! Greetings Frank

[@momchilvutov6263]

Hey Joe! As an ATCO trainee at the moment, I just wanted to say that you are spot on with everything. Keep up the great work!

[@flywithcaptainjoe]

Awesome! Thank you!

[@bernielui5791]

For the question at 9.00, the answer depends on the type of aircraft, for a cessna 172 Skyhawk, the altitmeter will show 99000 ft because it works like a clock, the same concept will also apply when a cessna hits 10000ft. Meanwhile, for commercial aircrafts, it will show negatives values depending on the elevation of your departing airport compared to your destination airport.

[@JeanLucCoulon]

QNE, strictly speaking, is not a setting, but the displayed altitude when the altimeter is set on the standard setting.

[@NikolaiUA]

There's an I think easier way to remember when is it a transition altitude and when a level: it is just the thing you were doing so far. If you are climbing - you've been doing *altitude* up until reaching the transition layer, so it is a transition *altitude* . If you are descending - you've been flying flight *levels* before reaching the transition layer, so it is a transition *level* .

[@mytech6779]

QFE can't be used in countries with high elevation airports because it would exceed the adjustment range of mechanical altimeters.

[@Marchetti7]

Thanks Captain Joe

[@PeterGithinji-fk4ix]

Hey capt Joe you're really inspiring us here out . Thanks for your educative videos. Hope one day I'll achieve this big dream of becoming an airline pilot🎉

[@ctar103]

Thanks for the great video. This answered a question on transition altitudes and levels I had that I was going to ask my instructor. 👍 Could you explain more on the cold weather adjustments and how to calculate this using the table? Does the adjustment decrease as you get closer to the airport at a lower altitude, so you have to constantly make adjustments as you go? Many thanks, Chris

[@billhull6842]

I like how you describe the altitude gauge. I am not a pilot. All I know about flying is you are supposed to keep the blue side up. lol When I was in college I became a Advanced Certified Scuba Diver. I can free dive to around 130 ft below the surface. I was also a primary diver for the Sheriff's Dept Dive Rescue Team! The things we learned with scuba diving is our depth gauge did not measure are depth but it measured the amount of pressure we were under to transfer the pressure into how many feet below the water we were. So, I understand what you mean when you say the altitude is based on the pressure of the air.

[@NikolaiUA]

Even more important is to keep the brown side down 😄

[@josephcameron530]

Great presentation. Very interesting. Thank you.

[@seyedkamalseyedzadeh-vt8rc]

thanks for the nice way of elaboration 😅

[@MrDjmid]

Great video , please make one for Charts explaining 🙏🏼

[@flywithcaptainjoe]

Coming soon!

[@FredrikHistherRasch]

As Joe points out the TA in the US is 18000ft, in Germany it's 5000ft, and in Norway it's 7000ft, i.e. they differ and you must always consult your local chart to check for the correct TA. Joe, why is TA different all over the world? Why is Germany's TA so low, while the US is quite high?

[@mytech6779]

Mostly because of the height of mountains, true altitude is needed when altitude above ground level is less than approximately 3000 feet. However flight levels are presumed to be less work for air traffic control because they don't need to announce the pressure setting for each sector. (Really doesn't save significant work in practice because they still need to track pressure for traffic below the transition.) In the USA 18,000 works well because most slow aircraft have an operational ceiling below 18,000 and fast aircraft traveling only a short distance (staying at lower altitude) will not cross many sector boundaries nor air-mass fronts and will have no need to cross the transition layer. Meanwhile most fast and long distance aircraft tend to travel closer to FL300. In the USA 18,000 is also our upper limit for visual flight rules unless flying no more than 2,500 above ground level. (We have 6 mountains high enough for this 2500agl rule.)

[@amittyagiat80]

Excellent video. Nicely presented. 👍

[@flywithcaptainjoe]

Many thanks!

[@FgTt-l4h]

Thank you for the video, Captain Joe.❤❤

[@LindaHurley-qm7uk]

You again

[@AirJoe]

No way he put me in a video! 0:28

[@flywithcaptainjoe]

😂

[@LindaHurley-qm7uk]

Hi​@@flywithcaptainjoe

[@magicblockcraft]

Helped a lot. When i read about the real function behind this in my theory lessons i noticed it fit real well wich me current math topic in school. sets of curves that is (kurvenscharen auf deutsch), i pitched this to my teacher and she really took one lesson to dig into the topic with my class! if i had to guess, next lesson we will watch this video as a summery ❤

[@ehsan83]

Excellent knowledge thank you captain Joe 👍🏻

[@shailendrachiplunkar7195]

Nice information Sir

[@alexkazzeo6208]

Good video. Thanks.

[@Av_Geek-Nouh_Chahin]

If the QFE is set at an airport then at touchdown in a lower airport, the altimiter will show a negative value

[@pabloalvarez5405]

Hola Joe…well explained👏

[@Aero-ScienceIdeas]

good discussion

[@alanrichard8297]

Love from india ❤ 🇮🇳

[@ricardo2573]

As always greatly explained. I've been ATC for 30 years and I've used your videos for training many times. Once again I meet your channel. Could you explain the correlation of Mode C indicated altitude with altimeter readings? Is for Pilot's altimeter or second? Plus: in the transition layer between TA an TL. Barometric reference is different depending on whether the aircraft is letting down or up on climb. So altitudes are a challenge in those...1000ft layer

[@BloxyGamezAV]

Captain Joe how similar would the EASA ATPL be to the UKCAA ATPLl?

[@flywithcaptainjoe]

More or less the same

[@BloxyGamezAV]

@@flywithcaptainjoe thanks

[@brombrom1522]

Gord, yer making my head spin!

[@anshuchil2281]

In the example, you mentioned to reduce the QNH setting and somehow the altitude decreased. I feel that reducing the pressure on the QNH should give increased altitude. Correct?

[@alexs1444]

Hi Capt, why did u delete the dme arc video? Could u upload again, pleeease?😊 🙏 thanks

[@sameeralazawee7524]

Thank you

[@freddyznwnewsamuel]

can you make a video on the vertical speed indicator

[@KangJangkrik]

I won't be a pilot anytime soon, but this knowledge is very useful for hardware engineer like me

[@arkanoid1980]

I'm waiting for the aviation to come to the present time and not post war era. Too many procedures that should be totally automated. Looking to accidents reports it's almost always human errors. It's incredible to me how it can be allowed nowadays to constantly set parameters here and there in order to fly safely.

[@frankmckenzie8981]

right, very good remark!

[@beverlymontezina4440]

❤❤❤love this @captain joe

[@brad4057]

Great vid love it

[@채란-k5e]

잘듣고,보고있어요

[@shawnverizonverizon2598]

Yeah buddy!!

[@Arturo4586]

The static pressure measured by the altimeter equals the weight of the atmosphere above, the higher you fligh the lower the weight of the air above . When there is a strong wind, the pressure is reduced significantly giving a false local reading. That is the only correct physical explanation.

[@joetiskas8316]

Amazing 👍🏻

[@채란-k5e]

최선 즐거움으로 지치말고❤파이팅

[@Bycopikeynes]

❤ execelente como siempre 👍🫶🏻🤍

[@MikeDCWeld]

2:49 I've never seen them on an A320, but I see them all the time on B767-300Fs.

[@ZK-APA]

Its just below and slightly behind the forward door on the 320

[@MikeDCWeld]

@@ZK-APA knowing where they're located won't help since I'm never that close to an A320.

[@ZK-APA]

@@MikeDCWeld if you are ever travelling on a 320 and they're using stairs to board, then maybe you can see them I guess

[@keviny1936]

Do newer planes use GPS to establish altitude, and how does that relate to flight levels?

[@flywithcaptainjoe]

Also using QNH!

[@andrewwinfield8592]

Understanding pressure differences is so important to the British passenger - it's the secret to getting the milk from the little carton safely in your cup of tea rather than sprayed in your face when you break the seal!

[@flywithcaptainjoe]

Good one😂

[@samuelgit]

Intesting thank you

[@thomassanabria1599]

Loving aviation

[@AmigaMuadib3D]

Q: do you do temperature corrections when flying QNH or QNE??

[@robbo21blue]

Is there a specific reason why the transition altitude is set specifically at FL180?

[@jaycee330]

Because we don't have as many high mountains in the USA to warrant different transition levels as opposed to Europe.

[@evgenytsvetkov2781]

Thanks a lot❤

[@flywithcaptainjoe]

You're welcome 😊

[@studyacc4063]

9:00 altimeter would be in negatives because you went below the altitude of departure airport

[@vfx7t]

QNH NATURAL HORIZON /QNE NATURAL EARTH/ QFE FIELD ELEVATION 😇

[@MrRoboticBrain]

I'm curious what altimeter setting systems like GPWS use? AFAIK ATC only sees QNE altitudes and compensates for it as necessary. But how do all the onboard systems get the correct QNH if the pilot set it incorrectly?

[@jaycee330]

GPWS uses radar instead of altimeter.

[@jonathanhernandez4304]

Answer. To land I will literally be negative 0 feet elevation. I forgot the numbers in your video but I think I'd be 210 feet below zero feet from the previous airport.

[@stachowi]

Can you use your radar altimeter to reset your altimeter in flight?

[@flywithcaptainjoe]

No!

[@jaycee330]

Absolutely not.

[@shikshokio1]

A question: why use a QNH at all at an airport, or close to it, and not QFE? What do I care what is the airport elevation relative to sea level? Isn’t it better to use QFE and just see the elevation above ground, that is to see zero reading at the ground?

[@jarekferenc1149]

Good question! However, all the mountains are described with the height above the mean sea level (in feet amsl or meters amsl), and not by height above the airport level. Maybe this is the answer?

[@shikshokio1]

@@jarekferenc1149 I think you are right. Collision with ground at the airport is avoided by the radio altimeter. The QNH setting is used to avoid collision with mountains. I guess.

[@ZK-APA]

Because the 0 height the QFE gives is only valid at the airport itself. Everywhere else it doesn’t make sense as elevation changes, so it gets inaccurate very fast. Only time QFE makes sense to use is if one is doing circuits at an airport, that too during early stage of training.

[@frankmckenzie8981]

Because when you stay in the erea of a local airfield and below the corridor of commercial flights, it has no sence to apply the QNH

[@TwitMoe]

Hey buddy. So when is a radio altimeter used?

[@jaycee330]

Primarily on landing.

[@TwitMoe]

@@jaycee330 Thanks

[@jaycee330]

@@TwitMoe No problem. It's done on final approach, since approach charts reference radar altitudes.

[@pederwaldenstrom4807]

Is there any redundancy? Any other backup system if the altimeter fails or some sort of safeguard for pilot mistakes? Why not use GPS?

[@ZK-APA]

Technically, multiple altimeters is the redundancy.

[@jaycee330]

Most airplanes have redundant indicators, as well as redundant baros. GPS is for positions, but doesn't do well for altitude if you are moving fast.

[@NikolaiUA]

I think you forgot to explain when QFE is used and how is it dangerous.

[@assafco1000]

Does the QNE basically means the planes may be flying at actual different altitude than the one that is displayed? Is the 35000feet pilots see can actually be 34 or 37 for example?

[@jaycee330]

Since pressure can change, then yes, the true altitude may vary - but every other plane assigned to that level will also be flying at that altitude as well. ATC gives sufficient vertical separation so that you won't drift into another level.

[@shaheebel-bearny2296]

QFF... Is there any easy way to remember the q codes

[@MeaHeaR]

so what are the level height values ¿¿¿

[@robroysyd]

This can be a real trap when flying out of grass runway say22000' above MSL. You might think you're under 10,000 but you set the altimeter tp zero on the runway so you.re actually at at 12,000' and in controlled airspace without even a radio.