What is Pressure Altitude and Density Altitude in Aviation? | Flight Training | FlightInsight

The air we fly in is never the same. The density is affected by altitude, air pressure, temperature, and humidity. Want to take online Private Pilot Ground School and finish your training? Visit flightinsight.... and sign up for online courses today!
We need an easy way to compare different conditions on different days so we can predict how well the airplane will perform.
This is what the International Standard Atmosphere is all about. It's a fantasy land, where the pressure and temperature are always the same no matter what. Pressure Altitude and Density Altitude are the altitude you would be at in fantasy land, if you were experiencing the pressure and temperature conditions you currently have in the real world.
This excerpt from Private Pilot Ground School should help you with these ideas, which is a common challenge for students and experienced pilots alike!
Want to take online Private Pilot Ground School and finish your training? Visit flightinsight.... and sign up for online courses today!
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[@flywithgaurav163]

so far the best explanation. you cleared my concepts. thank you :)

[@flightinsight9111]

Glad to hear it! Hope you can move on to some other topics now!

[@plotholedetective4166]

I've decided im going to be a pilot and spent a week at the airport asking questions about where to start. I was told to memorize everything in this series, so you're about to get a bunch of views from me rewatching each of these several times over. Let the binge begin

[@AwestrikeFearofGods]

Wise decision, doing as much ground school as you can, before flight training. A third-class medical certificate is another good place to start. A certified Aviation Medical Examiner is required to administer the exam. If you might be interested in going career, get a first-class medical (in lieu of third-class) now, to help predict your future medical eligibility. There are commercial positions (e.g. flight instructor) that require only a second or third-class medical, but airline captains require a recent first-class medical. As a warning, flying is a rather expensive hobby. Assume a PPL will cost at least $10-20k in rentals, instruction, training materials, flight equipment, and fees. Few people are able to get their PPL by the 35/40 hour minimum, so budget for more hours. Fuel is usually the greatest cost in general aviation, and that is (mostly) included in wet-rate rentals. An exception, you might only get partial reimbursement when filling up at an airport with high fuel prices.

[@Fredopia_TTV]

@@AwestrikeFearofGods Pursuing my dream🫡

[@AlexanderGarzon]

This is so far the best explanation I ever found on youtube. I would add also how to calculate them with the E6B and you have the perfect video.

[@flightinsight9111]

Hey thanks for the feedback! Check out this vid if you want to see how to use the E6B for this and other calculations kzbin.info/www/bejne/bpWXq5lthr6dfNk

[@allthatinformation]

Thank you so much. I'm a beginner to flight simming , and never understood why the ATC used to say altimeter 29.2...etc. I understand how it is important now.

[@careerbreakoff]

Thank you, I get it. Pressure altitude is a made up standard and is used to compare with the real world. It was confusing because the term 'Low pressure altitude' actually means the air pressure is HIGHER than the standard. Nothing to do with 'low pressure' but rather a pressure associated with a lower altitude!

[@romeocudal8356]

For the longest time I had trouble understanding the terms used and their differences such as (PA, DA,ISA, atmospheric pressure, ISA temp and OAT) specially since they have similarities yet they connect with one another. This video saved me, you sir deserve more views. Sadly I know of student pilots out there that memorize these calculation and meaning easily but completely lack the understanding and way of explaining it. Keep up the videos man your diagrams are awesome

[@issak1230]

Today is the first time I clearly understand density altitude and the calculations.. I am going to sign up for the IFR course ! Thank you for the step by step instructions!!!

[@flightinsight9111]

You’re welcome. We’d love to have you onboard for your training!

[@jimmbbo]

Density altitude can be thought of as the altitude in the standard atmosphere that the airplane "thinks" its flying in, corrected for non standard temperature and pressure.

[@corystorch8367]

So according to the ISA, if you're at an airport 1000' above sea level and experiencing 28.92" and 13°C. Shouldn't your DA=1000'? According to those formulas: PA=1000+(29.92-28.92)*1000 PA=2000' DA=2000' + 120(13-13) DA=2000' So if at 1000' your pressure and altitude are where they should be according to ISA (28.92" and 13°C) then why is your DA=2000'?

[@flightinsight9111]

If you're at 1000' elevation and the temperature is 13°C and PRESSURE is 28.92, yes you'll be around 1000' density altitude. If at 1000 feet and 13° but ALTIMETER setting is 28.92, your density altitude is around 2000 feet ("around" because the 1 inch per thousand feet is a rule of thumb) There's a difference between barometric pressure and altimeter setting. The altimeter setting is the barometric pressure that we imagine we'd get if we bored a hole in the ground and stuck a barometer at sea level. This is why no matter what altimeter setting you look at, it's corrected to sea level - so we can compare them against each other. Have a look at the Denver altimeter, since its 5000 feet elevation, you'd expect it to be about 5 inches lower than here in Maryland, but it's not off by nearly that much. If the altimeter setting wasn't corrected to sea level, we wouldn't have to add back the field elevation into the pressure altitude formula. Any altimeter setting you read off a METAR or otherwise is taking the field elevation into account. Hope this helps!

[@SGTSnakeUSMC]

ATIS altimeter setting "baro setting for your altimeter" is what you use in the formula. This is not what is actually present outside. It is what it would be at sea level. The baro setting under the conditions in your example would actually be 29.92; thus, the PA and DA would be 1000'.

[@jacksos101]

@PozPoz This confused the hell outta me as well. Much clearer to say 'altimeter setting'. In saying that, I love the effort that this guy puts into all these resources, and am eternally thankful for it.

[@peterlazuric5641]

I watched your interview with Gabriele on Pilot Climb and thought I would check you out

[@flightinsight9111]

Great! Gabriele is a lot of fun and has tons of knowledge!

[@andresgarcia438]

Why the +120? What is the 120 referencing ?

[@cuso0531]

love ur channel dude great explanations and saving me money, ez sub

[@tannu1887]

Hello sir can you explain the statement ''With constant temperature if pressure increases the density altitude also increases''

[@murderedout5650]

Thank you very much for taking the time to show us this. I was having a hard time until this video

[@flightinsight9111]

Thanks, Luis! It's a tricky area. Sometimes all that's needed is a different approach.

[@rajibkudas123]

Thank u...can u please explain..as lapse rate is -6.5°C/km..i.e...0.0012 °C/ft...where from 120(..) came into equation....

[@nathaliacoelho4065]

This video blew my mind. Extremely helpful and I finally understand this damn thing!

[@CheeseLo]

I really enjoy and appreciate your videos. Excellent. Thank you. Re density altitude: seems like a butt-load of confusion could be eliminated by just reversing the words of the name, i.e., “altitude density”…because I think that’s what the concept is really calculating. Just a thought.

[@leonardoavakian]

Fantastic explanations, very clear. Thank you

[@runway16_right94]

thank you, thank you.

[@eesaladeekshith6926]

Good explanation. Thanks mate! ✌️

[@scottstewart2376]

Thank you! Thank you! Thank you!

[@flightinsight9111]

It’s a pleasure!

[@SaurabhKumar-hr7fn]

Could you explain the diff between true and pressure altitude?

[@flightinsight9111]

True Altitude is the height above sea level, or MSL. This is what your altimeter reads when it's set correctly. Pressure altitude is what your altimeter would read if you set it incorrectly, by putting standard pressure of 29.92 in the window. Pressure altitude is a measure of the density of the air at a certain altitude. So like this video says, if you're at sea level and the pressure is 28.92, setting 28.92 into the altimeter would give you the correct or true altitude of 0 feet. If you set standard pressure in however, 29.92, it would not read your true altitude but your pressure altitude, which would be 1000 feet.

[@SaurabhKumar-hr7fn]

@@flightinsight9111 Thanks for the prompt reply. I understand how to calculate the pressure altitude based on the reference datum of 1013.2 hp, but I want to know what does the value of the pressure altitude means to us as pilots? What do I understand by pressure altitude being high or low?

[@flightinsight9111]

@@SaurabhKumar-hr7fn in a nutshell, the higher the pressure altitude, the worse your aircraft will perform. Think of pressure altitude like the altitude your aircraft feels like it’s in. Airplanes perform worse at higher altitudes due to less dense air, so high pressure altitude means your plane will use up more runway in takeoff and landing, and have a poorer climb rate, among other things

[@noahpaul7716]

Very Helpful video, thank you!

[@flightinsight9111]

Glad it helped. I’ve seen Examiners test on pressure altitude a lot bc it’s a tricky area

[@jakew9887]

Great Video. Thanks

[@georgeb6909]

Best explanation thank you😀

[@flightinsight9111]

you're quite welcome. Not the easiest concept until you look at it a few different ways

[@Benj305]

Excellent explanation you've got a new subscriber. I do have one question though I noticed most people know how to get Density altitude but, is there a way to determine a flight will be safe since the take off, climb, and landing charts go off of pressure altitude. I just want to know for myself. I see most people talk about how pressure altitude and the charts can help to see if you have enough for a safe ground roll on takeoff and landing but how would I know if I am safe to fly in mountainous terrain. Most from what I have read is to wait for temperatures to lower before attempting those flights. Any advice would be appreciated thanks.

[@flightinsight9111]

That's a great question. Most of the performance charts in the Cessna POHs use pressure altitude, then provide data based on air temperature. This is an indirect way of using density altitude to calculate performance, since density altitude takes pressure altitude, and corrects for temperature. If you have these charts and can compute pressure altitude, you're able to determine performance. Other aircraft performance charts work differently, using density altitude to directly compute takeoff, landing distance etc, but the results are the same. Low temperature decrease density altitude, and therefore increase performance.

[@Benj305]

@@flightinsight9111 Thanks a lot that helps I am trying to learn as much as possible to make sure when I take my commercial there is no reason to fail I appreciate it.

[@flankerskioneniner4290]

Thank you 👍👍

[@sirusguyrus2445]

Im trying to figure out how the curve of the earth is factored in. Can anyone explain if altitude is accounting for that.

[@flightinsight9111]

Wait, the earth's surface is _curved_ now!? Just joking. I'd say that both the aircraft and the atmosphere it's flying through are subject to gravity. As the aircraft flies level, and the earth curves slightly away from it as it flies along, an additional amount of energy would be required to increase height above the ground, so altitude doesn't change. Think of a spacecraft in orbit: its default position is to stay at the same altitude (assuming circular orbit) unless a boost of energy allows it to go higher. The aircraft is no different, thrust and drag are in equilibrium in both cases. As far as pressure altitude goes. Since the atmosphere curves with the earth because of gravity, a constant height above the ground will register as a constant altitude on the altimeter. In short, we don't have to worry about curvature of the earth on the altimeter because the atmosphere curves with the surface, as does our aircraft when pitched for straight and level flight.

[@sirusguyrus2445]

@@flightinsight9111 Thanks for the reply!!! You might of guessed I'm trying to prove the earths is round to a flat earther.

[@flightinsight9111]

@@sirusguyrus2445 Haha yeah I've heard this one about how the earth is flat because planes don't have to constantly 'pitch down' to adjust for curvature. Flat earth stuff is strange but can be fun sometimes and at least get you thinking about some of the physics of flight. No harm no foul I guess.

[@manlor13]

Excellent

[@rajibkudas123]

When you set the altimeter to 29.92...it should show zero....isn't it....not -200....

[@flightinsight9111]

Hi Rajib. In this example, sea level pressure is 30.22" (this goes up and down with weather changes). So if that pressure is set into the altimeter, yes the altitude will read zero. However, when 29.92 is set, it will read lower than zero, in this example, -200 feet. This is the pressure altitude in this example.

[@SGTSnakeUSMC]

Good vid

[@TankNSSpank]

Why don't aviator just communicate in terms of air pressure or air density? Why bother changing it into some bogus altitude measure.

[@flightinsight9111]

It’s not a bad idea, since all of the factors we’re talking about here that affect performance deal with air density. I think by using concepts of pressure and density altitude though we make performance more relatable since pilots are used to experiencing different conditions at different altitudes. Saying the air is “such and such psi of pressure” is one thing but saying it’s like being at 1000 feet makes us say, oh yes just like Kansas City.

[@TankNSSpank]

@@flightinsight9111 That make sense. Thanks

[@robertotto7673]

YOU SIR, THANK YOU ! Great video and i will subscribe :)

[@flightinsight9111]

Glad you enjoyed it. Good luck in training!