Cold Temperature Altimeter Error is pretty dangerous! | X-Plane 12 Demonstration

[@_Schisko_]

Please more educational videos like this! They are very good. Keep it up!

[@rickharriss]

Interesting. I never considered this an issue. so much to learn. Thanks for this.

[@flightdeck2sim]

Cheers Richard! Wasn't able to talk about it until a sim actually modelled it properly! FD2S

[@jcommtube]

Great video! Would you be able to record a similar one in MFS? Supposedly MFS, specially after the fine tuning and fixes by the WT team, also models temperature effects on geopotential height, but I would love to see a detailed analysis of how accurate it does the thing :-)

[@youronlycow]

Thanks. I have a real life scenario question though. So you apply corrections to all published procedural altitudes yes? What If ATC changes your SID/STAR and departure or arrival runway? Are you going to be there calculating again all the different altitudes and applying to all published altitudes on FMC again? Changing SID/STAR/RW already creates stress for reprogramming. Then, How much time would that take to painstakingly calculate and input into the FMC and constantly telling ATC your altitude correction when they assign you a climb/descend altitude? Are you going to be calculating, interpolating to the degree? What about other aircrafts in the vicinity? Are they going to be doing it too? If everyone one is doing it, will everyone get the exact same numbers when interpolating and correcting? If no, will everyone then be kinda flying at all sorts of different altitudes? Should everyone just request radar vectors for departure/arrival so they can just dodge this constant calculation, interpolation, modification and advising ATC of correction which makes RT even more congested and longer… Constantly calculating and modifying numbers increases workload and reduces margin of error though I understand it’s significance. But how significant? Depends on actual temperature and height above altimeter reference source. What do you think?

[@HansRo4ming]

Is this related to ISA deviation and does it correct the STD setting for level flight etc?

[@syman6695]

Just studied this in Meteorology for my ATPL, vey cool to see it implemented!

[@_jamesrayner_]

I did my MET ATPLs literally last week. Wish I had seen this a little sooner 😂

[@LBT-sy4dp]

Really good content captain, keep working hard!!!! Greetings from argentina!

[@Klice82]

woundn't it be easier to correct altimiter instead and fly posted altitudes?

[@rakxk]

I was asking myself the same question.

[@joshuasetford4032]

So does the opposite need to be applied with high temperatures? Although it would put you high so actually giving you more terrain clearance I suppose it could make you unstable on a non-precision approach if the temperature is particularly high as can be found in destinations like Dubai.

[@SandroSalgueiro]

Great video. If you were flying an RNP AR with temperature-corrected Baro VNAV, would you also use V/S and LVL CHG modes to follow the vertical profile? Or is there a way to use VNAV for a temperature-corrected RNP AR approach?

[@Arcadiez]

Do not commence the approach when the aerodrome temperature is outside the promulgated aerodrome temperature limits for the procedure. While APV approach would not be available, a NPA to LNAV minima could be conducted provided the correct cold weather temperature corrections are applied: LNAV/VNAV * Temprature correct MSA * Temprature correct LNAV/VNAV DA, set on PFD * Temprature correct altitudes below corrected MSA to FAF * Do not correct alltitudes from FAF to MAPt (Including FAF) * Temprature correct missed approach altitudes below corrected MSA Check chart temperature restrictions. If the reported airport temperature is outside the limits revert to LNAV minima LNAV * Temprature correct MSA * Temprature corect MDA, add 40 feet(airline specific requirement to add 40' for NPA), set on PFD * Temperature correct all altitudes below corrected MSA including FAF to MAPt altitudes (RW point cannot be corrected in the FMC) * Temperature correct missed approach altitudes below corrected MSA VNAV is the recommended vertical mode for the initial and intermediate approach segments." With the added corrections as described above, we normally fly with LNAV/VNAV engaged. Info taken from RNP Pilot Reference guide (again only use whatever instructions your airline says, this is just a demonstration of what we do)

[@bunnyfeng]

where can we find the correction chart you showed on screen for a brief moment?

[@flightdeck2sim]

Type in Google Cold Temperature Correction Table 👌🏻 FD2S

[@wesleyyin]

Superb video! After watching it, I read about the subject to clear my confusion. Could you please check it out? First, in addition to setting the altimeter provided by the tower, you are talking about the **additional** low-temperature correction. If you don't correct it, then although the altimeter reading will be correct when you land at the airport, it will read dangerously too high (so you fly too low) when flying over approach fixes. The reason is that at cooler temperatures, the rate of decrease in air pressure due to altitude change is greater. "The rate of decrease is greater" is the key. Therefore, the error in altitude is not only greater at colder temperatures but also at higher relative altitudes above the airport. Hence, the steep approaches to airports in cold weather often require the correction.

[@mr.unicorn8847]

Super interesting, but if the MSA at 4400 is held, what would ATC read? Would the ADS-B show 4400, or the lower 3600 and vise versa?

[@MikeSierra8282]

my prayers have been asked....thank you for this material, this was the topic I was struggle with

[@vorlonb3]

Must admit i didnt know this FD2S little aspect and its caused a few flutters over the years nice to know.

[@samuelemendozzi]

Do you play on MAC os ?

[@FlightSimmerX-Plane]

Beautiful. Just cannot understand yet how to read through the altimeter reference table.

[@richardboll8763]

It would be interesting to see the effects of hot temperatures. For example, on a 40C day fly an ILS at KORD with multiple stepdown fixes in the intermediate segment outside the FAF using approach mode and tracking localizer and glideslope. Do you go below the published these stepdown altitudes while n the glideslope?

[@flightdeck2sim]

Great question Richard! As it's less dangerous than cold temperatures there are no correction made to hot temperatures but it does pose other issues such as high energy approaches when using VNAV An ILS isn’t affected by temperature corrections, you just need to adjust the platform altitude and minima. The glideslope is fixed so the altimeter will overread if it's cold or underread if it's as you do your altitude distance cross checks but you’ll be at the correct true altitude FD2S

[@richardboll8763]

@@flightdeck2sim Thanks Captain! The ILS glideslope and hot temperatures has been a problem in the US, namely at those locations where simultaneous parallel approach operations in use, for example Chicago O'Hare (ORD). If you look at the ILSs for the runways, especially the 10 complex, they have multiple stepdown altitudes in the intermediate segment. The glideslope crosses those stepdown fixes on a standard day at the published altitudes. However, on a hot day the glideslope, as you note is unaffected by temperature, will cross these stepdown fixes below the published altitudes. The altitudes are required for ATC to apply the 1000' vertical separation requirement at the point of turn on for the parallel traffic. Also, some of those altitudes are placed at the floor of Class B airspace. US regulations require aircraft to remain within the Class B airspace when operating into and out of the primary airport. On a hot day, tracking the ILS glideslope outside of the FAF can result in descending below these altitudes, and result in a potential pilot deviation by ATC. This has been an issue at KORD and KDFW recently. It's great that XP 12 now can simulate this and we can show pilots that it's not always appropriate to use approach mode and track the glideslope that far out. Enjoy your content! Always look foward to your next video!

[@flightdeck2sim]

@@richardboll8763 Ahhh I get you! Yes prior to intercepting an ILS any step down altitudes are going to cause issues! FD2S

[@ichbineinstrau2296]

Why do you fly mostly the Zibo and not the PMDG in MSFS? Btw your Videos are VERY nice ; )

[@airbus7373]

Question: with temperatures in cruise regularly exceeding -30 degrees, do you do this in cruise? If so, how should it be done?

[@flightdeck2sim]

Great question! You only need to make corrections to heights below the MSA. In the cruise no correction is needed and it's important you don't make any corrections as you'll be at a different altitude to the traffic around you. FD2S

[@SimAviator]

This was what I needed, Thank you!

[@srvnikos]

Do we really deserve all of this knowledge? Great stuff!

[@patrickweisse4383]

Very Interesting and instructive . Thanks

[@GabryelHdPerformance]

In case of hot temperature? In teory I have the opposite altimeter issue? There are system that correct automaticaly theese altimeter issues?

[@flightdeck2sim]

That's exactly right. It's less dangerous than cold temperatures because you're higher but it does pose other issues such as high energy approaches when using VNAV but no correction are made for higher temepratures. FD2S

[@somewaresim]

Learned something new again. Thanks!

[@SSAviation737]

Wow I learned a lot from the altimeter from this video! Thanks FD2S!

[@flightdeck2sim]

Very welcome! FD2S

[@rhwh93]

You are such a great pilot. Such an inspiration to many!

[@mikemoreno4469]

Very interesting. Thanks, Captain.

[@pannegoleyn9734]

Good afternoon, Captain! Good to get another lesson

[@pannegoleyn9734]

I'm slightly confused here: a low temperature means higher density, which I'd naively expect to mean that pressure is higher than expected, but that would make the altimeter read a lower altitude than you're actually at? What do I have wrong?

[@Therealblubblego]

As shown in the diagram at the start of the tutorial, with lower temperatures the air is denser which means the layers of pressure are closer to each other. At a true altitude of 5000ft in a standard atmosphere the pressure is around 850hPa. The altimeter is calibrated to a standard atmosphere and if it reads a pressure of 850hPa it will show an altitude of 5000ft. In that example the altimeter shows the correct altitude. Now in an atmosphere where the temperature is lower than standard (15°C at sea level) the 850hPa pressure level will be at an lower true altitude! The altimeter will still show 5000ft at the 850hPa level but your true altitude will be lower because the 850hPa pressure level will be closer to the ground. Thats the danger, the altimeter tells you that you are higher than you actually are. Correct by adding 4% per 10°C below standard temperature or use a temperature correction table.

[@SupersonicSynthwave80]

Isso é um cacoete difícil de tirar da cabeça. Ensinaram que a Densidade é ligada a maior pressão sempre. Isso nos gases não é bem assim ! A Baixa temperatura reduz a pressão , mesmo estando muito mais denso que um ar mais aquecido; que aumenta a pressão. Costumamos a pensar como se fosse um cilindro de volume constante, colocando mais matéria e assim aumentando a Densidade dentro do cilindro e por consequência , tendo uma elevação na pressão. Isso na atmosfera não acontece , pois o que importa é a temperatura da energia cinética dos gases . Mais frio , maior densidade, menor pressão, devido a menor agitação molecular . O Barômetro sempre mostrará a queda da pressão em relação ao gás que está dentro do aneroide, que por estar com pressão padrão , expandira se exposto ao ar Mais frio e menor pressão , dando a entender que está havendo uma elevação na altitude. Na verdade o que importa é a temperatura pra sabermos de fato a pressão real a que estamos voando .

[@CryptoBlog230]

Damn I have missed this intro

[@adamwallace0929]

Thanks for the video 👏

[@StarflightVirtual]

Hello hello, nice video again. One please...can you pls do a App and explain in Skathos LGSK ? Thanks Matthias

[@flightdeck2sim]

Here you go sir! kzbin.infoSM6ek3v14uc?feature=share Be sure to check out my Destination Route Map! www.google.com/maps/d/edit?mid=1U_gpQ_CGrqNQLv4-QFLdZeAU6MXykOs2&usp=sharing flightdeck2sim

[@StarflightVirtual]

@@flightdeck2sim Oh Shit...i am sorry...why did i miss that ?? ... Sorry Matthias

[@flightdeck2sim]

@@StarflightVirtual Haha no problem my friend! Enjoy! FD2S

[@StarflightVirtual]

@@flightdeck2sim Yes i will, i have this Airport now in MSFS and tried a Landing, but it was not really easy 🙂 I am sure, as of the Video, i can do better...

[@Sbottish]

Beautiful landing!

[@kickinit333]

Brilliant.

[@robertosoares1969]

nice.

[@virtualaviator21156]

facts

[@n666eo]

Thank you for this very educative video captain !! Do you no if by chance, MSFS is also correct on the cold temperature altitude error ?

[@flightdeck2sim]

You're welcome! MSFS has not modelled this unfortunately. FD2S

[@n666eo]

@@flightdeck2sim Thanks for this quick reply ! I will use it only on XP12 then... ;)

[@franckcagnes6370]

@@flightdeck2sim hello, but why msfs have different altitude for atc on vatsim depending on the location then ? If I fly in the canada my cruise alt is lower on simaware than what I have in the plane (when baro std). Also if you change live weather on/off during cruise you can see a huge difference. I'm confused.

[@flightdeck2sim]

I should think the difference you’re experiencing is the pressure difference between local QNH and STD, cold temperature altimeter error is not in modelled in MSFS. FD2S

[@franckcagnes6370]

@@flightdeck2sim ho okay thank you very much for the clarification, I was mixing two concepts lol

[@planepilot1892]

Good afternoon from Spain!

[@Zinericks]

Hola pana

[@NoTalentCreator]

22:00 now to me:)

[@planepilot1892]

@@Zinericks eeyy

[@planepilot1892]

@@NoTalentCreator lol, so good evening hahaha

[@flightdeck2sim]

muy buenas! FD2S

[@nhall00195]

But flying is easy and the plane flies itself! 🙄