Outside air temperature

Outside air temperature is the temperature of the air around the aircraft, measured clear of engine heat, sunlight effects, and other local influences. It is used in performance calculations, altitude corrections, icing assessment, and fuel and climb planning. A higher OAT usually reduces aircraft and engine performance, while a low OAT can increase the risk of icing. Pilots read it from the aircraft instruments or performance data and use it when applying the POH or flight manual tables.