OAT and TAT?

[Kestrel_909]

Hello All,
I am hoping to become a pilot in the future but for now I have to content myself with Flight Simulator. I have a question regarding air temps, what is the difference between OAT and TAT? I think OAT is Outside Air Temperature and TAT is Total Air Temperature, but what is the difference between them?

Alos, not sure if this is on the Airbuses, but on the Boeings, such as the 767 which I fly quite a bit, what's the difference between the three autopilot commands?
Help is much appreciated!

[r_bonham-carter]

Hi Kestrel,

I cant answer your autopilot question but I will do my best to explain the difference between OAT and TAT:

OAT (outside air temperature) = the temperature of air under normal/undisturbed conditions outside the aircraft. This is known as the 'Static Air Temperature'

TAT (total air temperature) = as the aircraft speed increases, the air close the aircraft is compressed and because of this compression the air is heated. This is known as the 'Ram Rise'

If you add the 'Static Air Temperature' and the 'Ram Rise' together you get the Total Air Temperature (TAT)

I hope this helps.
Good luck with your flying!

[Kestrel_909]

Thanks r_bonham-carter,
Also answers another question, what is SAT which I now take it to be Static Air temperature. Thanks!