Q1. F/L 350, TAT -11 C, Temp dev from ISA +20, Find out OAT & TAS?
In ISA temp at FL 360 = -56.5 C and lapse rate = 2 C/ 1000 ft.
So temp at FL 350 in ISA = -56.5 + 2 = -54.5 C
Temp deviation = ISA + 20
Therefore temp at FL 350 (OAT) = -54.5 + 20 = -34.5 C
OAT = TAT - (TAS/100)^2
-34.5 = -11 - (TAS/100)^2
23.5 = (TAS/100)^2
TAS = 485 kts.