Found these but it doesn't make sense! Let me know...

 

 

SAT out of TAT

SAT(°C)=TAT(°C) -3 x Mach

TAT = -17 °C Mach 0.64

SAT = -17 – 3 x 6 = -17 - 18 = -35 °C

 

SAT out of TAT for higher Mach and lower Temp

SAT(°C)=TAT(°C)- (100xMach)-50

TAT = -31 °C Mach 0.74 You have 24 above M 0.50 SAT = -31 -24 = -55 °C

And what exactly doesn't make sense here???

I don't know whether your formula is correct but I don't see anything particularly wrong with the numbers.

By the way, even wikipedia has relevant conversion formulas.

I see how it works now! Sorry.

Why would a pilot require this

 

 

SAT out of TAT for higher Mach and lower Temp

SAT(°C)=TAT(°C)- (100xMach)-50

TAT = -31 °C Mach 0.74 You have 24 above M 0.50 SAT = -31 -24 = -55 °C

Why would a pilot require this

 

Aircraft limitations, icing conditions, pireps...

Why would a pilot require this

 

 

 

Pilot doesn't really require it (who said they require it?). Pilot needs to know fuel temperature - this is the most important temperature he needs when flying very high and in polar regions. But he got probes that show him what fuel temp is. Pilots who fly smaller, slower aircraft, in lower altitudes don't even have to bother about TAT/SAT, that's the same thing for them.

Pilot doesn't really require it (who said they require it?). Pilot needs to know fuel temperature - this is the most important temperature he needs when flying very high and in polar regions. But he got probes that show him what fuel temp is. Pilots who fly smaller, slower aircraft, in lower altitudes don't even have to bother about TAT/SAT, that's the same thing for them.

We do also need to know the SAT since that is also an aircraft limitation on many aircraft. Typically -54 to -65c and it is something that you may run into at high altitude in the winter, necescitating a descent into warmer air. It is also nice to know the SAT if you want to make a complete pirep.