Cold weather altimeter correction

[Driver170 42]

When flying in extreme cold conditions and correcting STAR altitudes. Does one apply the correction for Final Approach Fix altitudes also?

 

Is this necessary for FSX?

[pschlute 37]

Not sure what you are getting at here. The only thing that you change on the altimeter is the QNH when you are flying below transition level. That is related to barometric pressure, not temperature.

 

As far as STAR and FAF altitudes, you fly them as they are published.

[Vargveum 53]

Absolutely a fact that cold temperatures affect the altimeter as all pressure instruments are calibrated to ISA. 

 

Realworld we have to take this into consideration. Low temps = lower than indicated.

 

Not sure if FSX models this though.

[Driver170 42]

Yes thats right meaning in higher altitude correction! But also not sure if fsx models this....

[Vargveum 53]

 

 

But also not sure if fsx models this....

 

Well, I guess we can test it  ^_^

[jcomm 5,890]

Yes, very true.

 

Unfortunately, useless to get worried about it in MSFS or even X-Plane, or most of the simulators I know about. These sims do not model Geopotential height!

 

The well known: "from high to low, watch out bellow..." applies to both pressures and temperatures, because the colder air, being denser, also corresponds to a lower geopotential.

 

As far as I know  the ** only ** flight simulator that will, for the first time, model this effect, so common and realistic IRL, is Aerowinx PSX, about to be released - the 747-400 simulator. Hardy Heinlin, the Master of the 744 simulations, took even this into consideration in PSX's weather model  !!! 

 

BTW, and although it's not the same thing being asked in the OP, here's also a simple calculator for Air Density

[g_precentralis 191]

You can roughly calculate correction as 4% for every 10 degrees C off ISA

[kterz 49]

Hi,

 

we can do this in ASN if you like (we actually have taken control of ambient pressure, so we could calculate the ambient air density at the aircraft level based on real temperatures. We didn't, because we didn't want to risk making things too realistic for the average simmer).

 

BTW, Jose (jcomm) I don't remember you asking anything related in the 8+ months you participated in ASN beta testing :)

[scandinavian13 5,192]

 

 

we can do this in ASN if you like (we actually have taken control of ambient pressure, so we could calculate the ambient air density at the aircraft level based on real temperatures. We didn't, because we didn't want to risk making things too realistic for the average simmer).

 

DO it!  An option would be cool.

[jcomm 5,890]

Hi,

 

we can do this in ASN if you like (we actually have taken control of ambient pressure, so we could calculate the ambient air density at the aircraft level based on real temperatures. We didn't, because we didn't want to risk making things too realistic for the average simmer).

 

BTW, Jose (jcomm) I don't remember you asking anything related in the 8+ months you participated in ASN beta testing :)

 

 

Kostas,

 

I was referring to default FSX, not FSX with ASN :-)

And I did mention it as a wanted feature. I guess it was even considered for future work. Would be great to have!

 

Curiously, I suggested the same to Austin, for XP10, but he was too busy... Asked me to remind him again later :-) I will!

[Spin737 102]

I don't think most airlines worry about cold weather corrections until it's -25C or colder.

 

One airline I worked for started corrections at 0C.

 

It's a pain in the butt. For the small corrections starting at 0C, you're more likely to introduce an error than to fix one.

[FLEX1978 373]

I don't think most airlines worry about cold weather corrections until it's -25C or colder.

 

One airline I worked for started corrections at 0C.

 

It's a pain in the butt. For the small corrections starting at 0C, you're more likely to introduce an error than to fix one.

 

 

Exactly, I think if most people knew the hassle involved they would keep the feature switched off.  

[kterz 49]

OK, I'll add it to our todo list (low priority and as an option only). Let's see how this works... 

[Driver170 42]

If its a pain in the butt leave it out ;)

[dave_paige 11]

No, please put it in, if you can. And, yes, as an option. Thanks.

 

Dave