OAT reads incorrectly during climbing

[andersenbali]

I'm experiencing a consistent issue with ActiveSky FS on MSFS 2024 where the Outside Air Temperature (OAT) reads incorrectly during climbing.


What I've Observed:

• The OAT reading becomes increasingly wrong as I climb higher
• At ground level, the temperature appears correct
• During climb, the temperature doesn't drop at the expected lapse rate
• This affects aircraft performance calculations and aerodynamics

Version 9495

MSFS2024 1.7.27.0

WIN11

 

[netshadoe]

You mention OAT. Where are you grabbing that OAT reading?
There are a couple of sources of temperature, especially when you fly more sophisticated aircraft.
The provided information is vague. You don’t mention what you’re using, nor do you mention any more detail, so not much to go with here.

Are you looking at SAT (Static Air Temperature)?
Are you looking at TAT (Total Air Temperature?

OAT is in line with SAT, so you have to be sure you’re looking at the aircraft’s SAT.

If you’re looking at TAT, then, yes, the temperatures will appear high since TAT is the Ram Air temperature that is affected by friction and compression resulting in a higher temperature reading.

 

[andersenbali]

I need to clarify: I'm climbing at 250 kts, and at 8000 ft: (PMDG 737 - MSFS2024)

TAT = 13°C (same as ground temp)

SAT = 1°C (on FMC PROG page 2)

Expected SAT at 8000 ft (from 13°C TAT):

Standard lapse rate: 8000 ft × 2°C/1000 ft = 16°C drop

Expected SAT = 13°C - 16°C = -3°C

Expected TAT at 250 kts/8000 ft:

TAS ≈ 290 kts

Ram rise ≈ 8°C

Expected TAT = -3°C + 8°C = +5°C

Actual: SAT = 1°C (4°C too warm), TAT = 13°C (8°C too warm)

Hopefully this makes more sense.

Thank you

 

[netshadoe]

Those numbers look reasonable to me. The atmosphere isn’t a perfect science experiment, so the lapse rate does deviate from standard atmosphere in real life. Sometimes there is an inversion, and temperatures actually climb as you gain altitude. Its not uncommon for inversions to reach 10000ft.

Do your upper winds and temperatures in MSFS match the values in the box in your current condition page in ASFS?