Let's Talk About the Altimeter

Here's a short video about some of the peculiarities and nuances of the standard aviation altimeter. Let me know what you think!
Sources:
Flying Instrument Handbook
FAA AIM 2016
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Music Credit:
Backed Vibes (clean) Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0 License
creativecommons...

[@Neophobic]

this video deserves so many more views. you ought to make more about flying

[@spacebabycam]

around 2:30 the animation looks like as the baro setting goes up, the altimeter display decreases. they actually work opposite though - if you turn the knob up, the altitude goes up. think of yourself flying and keeping altitude constant, but you fly into an area of lower pressure. you'll be descending during that time because if your indication is the same, the height of the low pressure air above you had to increase to keep that weight the same. you realize it's time to get a new baro setting and turn your baro down to say, 28. now you altitude is correct and shows you lower, not higher.

[@Arturo-lapaz]

The pressure the altimeter senses is the weight of the column of air ABOVE to the beginning of space, not below! Using the standard atmosphere, starting at 1013.25 hectopascal and 15°C at mean sealevel at midlattitude and a temperature lapse rate of minus 6.5 °C per 1000 meters up to 11km, the pressure and density can be calculated by integration to determine the standard atmosphere pressure vs altitude relation for the sole purpose of calibrating world wide all altimeters.
Very different from the terrain elevation, never to be called altitude .
Crossing a pass where a wind is blowing across the altimeter will always display an altitude higher than the elevation of the pass, even though the collsman setting of a nearby airport has been correctly entered.

[@Arturo-lapaz]

Yes the use of the standard gravity of 9.80665 m/ sec² and the correct gas equation is essential:
rho = p / RT
R = 8314.4.../ M
M Molecular weight of air
T temperature in Kelvin
15 °C > 288.15 K

[@davidm8097]

Great video and the graphics really help. Eric I'm desperate to know how you built the animation of the altimeter at 2:14... was it in powerpoint?

[@ahmedjinan6600]

3:16 as a gas is cooled its pressure decreases

[@kevinstewart4400]

Yup I caught that too

[@WyllSurfAir]

very good explanation Eric

[@akken2112]

Thanks for simplifying altimeters, I'm studying ground school and this video took an abstruse subject and made it fathomable. You should title your video "Altimeters for dummies".

[@AK-sq1jl]

Always cool to see another AK.

[@domigrin4886]

Good explained, but the music is making me crazy. 😆

[@michaellochner9145]

I can imagine the infinitive variations of pressure we encounter in the atmosphere, and don’t call me Shirley.

[@marksill8020]

Liked the vid. Gave a thumbs up, but I showed this vid to a younger person who, when 16, will start their flight training. They had trouble understanding the theory. Maybe you could dumb it down some for 12-15 year olds, so they could get a grasp of the altimeter. Just suggesting.

[@An-wf4pv]

Has wrong video and explanation at 2:15. Altimeter should indicate altitude goes up as you change altimeter setting goes up. People can get confused

[@Johnwoo4545]

Took me a little while to understand this, but I believe your comment is correct. The indicated altitude on the dial should be increasing as the IN-Hg setting in the kollsman window is increased. This can be seen here - th-cam.com/video/dLdsdQa6cmo/w-d-xo.htmlm5s Otherwise, Eric your video is fantastic!, very well put together and a big help. (PS, I am no expert, so please confirm this for yourselves)

[@untyped12]

The demonstration is wrong. The needles should be moving clockwise if you are increasing the altimeter setting.

[@XPLAlN]

The video does not have the worng explanation. That particular graphic can be interpreted two ways though. The way I saw it each rung of the ladder bar represents a lower pressure going up the ladder. Therefore as the ladder was conceptually raised (by increasing the sub-scale) the instrument was effectively descending the ladder to higher pressure, hence indicating a lower altitude. There was only one pressure labelled (29.92), and we are used to scales increasing so it is a little confusing, but in this case the pressure is decreasing as you go up the ladder, increasing as you go down, and the graphic is correct.

[@daviddevine2415]

XPLAlN Johnwoo4545 Nedim Yusufov
I’ll add my two cents because there is rightly some confusion here. The video shows the sea level pressure, SLP, increasing (indicated by the rising vertical tape) and simultaneously the indicated altitude is decreasing. This will happen if the kollsman setting is unchanged and the plane is level. However, the video also shows the kollsman window setting increasing to match the SLP, which means that the indicated altitude should actually remain constant. Notice that when the dials and tape stop the plane is now 4500 above the initial QNH=29.92 but remains 5000 above the new sea level pressure (QNH=30.42)

[@hatran-jf6fm]

how did you do it can you share with me , thank you

[@johnman6234]

Good job, a very nice explanation

[@ytkdmr]

As you increase datum pressure, how altimeter reads lower values ?
Below video it shows opposite !
th-cam.com/video/vLXwyWRZpRQ/w-d-xo.html

[@oren5889]

Epic sign off

[@piper0428]

Background music is annoying

[@melaniekuula]

I found a real old one. Wish I could send you a picture

[@aaronekstrand758]

"It's up to you not to fly into mountains when it's cold outside."
This is actually the reason they no longer fly tours over Antarctica.

[@Arturo-lapaz]

Bolony The Gps altitude is accurate within meters and shows elevation, independent of temperature, all you need is a smart phone with Gps built in.
The use of pressure altimeter set to 29.92 is traditional and reliable, indicating flight levels, until the aneroid leaks, then there is a backup. Not easy to discuss here.

[@goodvives1038]

Thanks for this cool info

[@belsaraj]

Very gd video. Thank you.

[@UnlikelyHero]

Great video. But there's no such word as "aircrafts". The plural form of "aircraft" is "aircraft".

[@OUTSIDER40]

Interesting 🤔

[@downhlracr]

Oooooooooh. I get it.

[@hakantaskn1018]

İskenderun teknik üniversitesi. Harun Yılmaz hocama selamlar :)

[@user-by8yu6di1p]

I stopped listening to the video because of the music interfering

[@MeaHeaR]

Shé dusnt explaining how to bé readings oné