Cold Weather Corrections

[ask26]

Was flying with a Captain yesterday who said that in the Sweden (ESSA) the platform altitude is 2500 instead of 2000 to compensate for Cold Weather meaning that the usual Cold Weather Corrections would not have to be applied as even at -25C the true altitude is still satisfactory.

I've looked through the Swedish AIP (LFV - Air Navigation Services of Sweden (http://www.lfv.se/en/FPC/IAIP/)) but cannot find anything mentioning anything about this. Is this just a case of smoke and mirrors and I've been pulled a fast one? Thanks.

[MaximumPete]

Altimeter over read when it's cold and becomes significant above 300to 400ft .
I suggest you look in the Aerad flight guide where there is atable of corrections, very important for a Cat 1 approach

[BOAC]

Like you, ask, I am puzzled - how a fixed correction? That would appear to apply to around -50 degC.

Next time you meet him, ask for reference and in the meantime I would suggest carrying on as you no doubt are:)

[BOAC]

I think both you and MP have missed the point of the original question? It was NOT why do I need to apply a CWAC. I'm pretty sure ask knows, as do most pilots.

[Piltdown Man]

My understanding is that the pilot always has to make a cold weather correction whenever the temperature is below ISA-15. However, countries like Sweden and Norway will apply Cold Weather Corrections whenever they are giving radar vectors. But at some point you will have to make an approach and in order to verify your vertical profile, you'll have to have some numbers ready in advance. Unfortunately, you'll have to work these numbers out yourself.

As for the platform at ESSA he could well be right - minus 47˚C at sea level would generate a 500' error on a 2,000' platform. But what do you do when you leave the platform? At what DME should the descent be started? So again, unless you have made some corrections you won't have a clue.

[hvogt]

According to 4.1.3 of PANS-OPS, Volume I, Part III, Section 1, Chapter 4 it should be assumed that no temperature corrections have been applied by a State if nothing has been published in Section GEN 3.3.5 of the AIP.

The Swedish AIP does not quote any such correction, so I reckon ask26's captain was wrong.

However, countries like Sweden and Norway will apply Cold Weather Corrections whenever they are giving radar vectors. Not only Sweden and Norway (see 8.6.5.2 of PANS-ATM).

[Piltdown Man]

Not only Sweden and Norway (see 8.6.5.2 of PANS-ATM).

I totally agree. It's just that this question was about that part of the world.

[Hansoff]

FMS does it for you?

[DBate]

FMS does it for you?

Nope, the FMS will not calculate cold weather corrections for you - at least not on the ones I know ;).

[Henrik83]

Flying in Sweden; Yes, you have to do the altitude correction in cold weather even if the platform altitude is 2500ft. Unless being vectored as hvogt said. Tried it out last winter in -25c. Yes, it was cold... :)

Regards from Sweden

[hvogt]

Unless being vectored as hvogt said.Actually, Piltdown Man mentioned that. I just wanted to add the reference.

[BizJetJock]

Nope, the FMS will not calculate cold weather corrections for you - at least not on the ones I know

Ours do. Collins FMS6000
Selectable as default or for each approach, asks "are you sure?" if you give it an above ISA ground temp.

[ColdCalc]

I have never heard of a single standard correction. It is directly related to HAA and reported temperature. I have done a lot of research on this very issue on several government and international agencies ( ICAO ). I write iPhone / iPad aviation apps and before my ColdCalc (http://RSVP.ca/apps) app hit the app store I had to make sure is was right ! It's interesting to see the variation in corrections to be applied as it gets only slightly colder than 0c.
Be safe and apply those cold temperature corrections !

[DBate]

Ours do. Collins FMS6000

Nice, didn't know that existed. Learn something new every day.

Are you required to x-check the corrected altitudes by the FMS?

[ColdCalc]

Hi DBate. Unless your airline/operator and government agency has approved iPhones & iPads on the flight deck for operational purposes, you must cross check any data from these devices with your carriers approved documentation. I always have my F/O go through it manually through the approved charts to confirm my results ( just to be legal )!
I have never found a descrepency and I had 7 line pilots ( including two check Captains ) beta test the app prior to release.
As a matter of fact, one Check Captain uses it while running the simulator to make sure the guys up front achieve the correct results !

[DBate]

Hi ColdCalc,

thank you for your answer, however I was refering to BizJetJocks post above and the correction calculated by the Collins FMS6000 he is using on board the AC he is flying.

Concerning iPhone/iPad Apps and the correction values calculated by them... They do a pretty good job, however I use the official programm on our flight deck EFBs (and have my colleagues use that one as well). Whilst the results should be the same as the ones on an iPhone, the software on our EFBs is approved by the regulators - the Apps are not ;).

And since our EFB has now several little features installed and approved by the authorities (Snowtam decoding, Cold Wx corrections, DA calculation, etc.) there is no reason anymore to use any Apps at all.

But still, I check the values from the EFB for plausibility. Don't want to hit something just because there is a little bug withing the software :}.

[ColdCalc]

Yeah DBate, I did think you were replying to my post. Sorry about that !
The only aircraft in Our fleet with EFB's that perform the altitude corrections is the Embraer 175 & 190. I personally fly the A-330-300 and we don't have EFB's. Our B-777's have them but they don't perform those calculations either.
As a matter of fact, several B-777 pilots use ColdcalcPRO (http://RSVP.ca/apps/iPhone.html) as it is quick and precise. In seconds they have their corrected #'s while the other pilot goes through the charts confirming them ( and how accurate is interpolating between the rows ). They especially love it when there is a runway change or the G/S goes out and the numbers have to be raised to non-precision limits.:ugh:
I couldn't agree more with your last statement. ALWAYS DOUBLE CHECK !:D
Can anyone tell me what other aircraft (EFB's) calculate these corrections ? I don't know very much about exec jets. I'd love to know though. Thanks:ok:

[BizJetJock]

DBate,

At present there is no requirement to cross check it, but I suspect that is because the CAA has not cottoned on to the fact that it exists.

To illustrate, we used to be allowed to do GPS approaches because the equipment was certificated for it and we practised them in the sim. Now that there are airlines doing them and approaches in the UK we have to have all sorts of extra approvals to be allowed to do them!

Maybe I shouldn't have mentioned it in case you're a CAA spy......:eek: