How to find outside Air Temperature?
Hallo everyone,
I am a bit struggling to find the OAT. I found something only on the Performance page of my FMS. But it looks strange. So if I am cruising on FL 230 my Weatherprogram show me -32°C but on the Perf page I get an indication of ISA+00. As ISA is defined to be 15°C something must be wrong.
As I need the correct OAT to handle the Engine Intake doors correctly, I would be happy to get your hints.
Guenther
Comments
ISA+XX means the deviation from pre-defined standard temperature at specific altutude.
So, ISA+00 means, there's no difference between actual OAT and the standard temperature at FL230.
According to ISA, standard temperature at 0ft(sea level) is 15c and it goes down 2c per 1000ft, so, since FL230 is 23000ft, 23x2=46.
so temperature will go down 46c from 15c. so, 15-46= -31.
There's only 1c difference from the temperature weather program calculated, so we can ignore this.
As I'm not professional, I might be wrong, but I found this information in some tutorials.
Hi Guenther,
SAT = OAT (but not TAT). SAT is showed in the Engine Display
Thank you sputnik for your very good explanation and also to Frank for additional information. Now its all very clear.
Regards Guenther