At what engine fuel temperature are takeoffs prohibited?

Takeoffs are prohibited at an engine fuel temperature of 5°C or lower because this temperature is critical for ensuring the fuel system operates effectively. If the fuel temperature is at or below this threshold, it can increase the viscosity of the fuel, leading to inadequate fuel flow to the engines. Inadequate fuel flow can result in reduced engine performance or, in extreme cases, engine flameout during critical phases of flight such as takeoff.

Maintaining fuel temperature above this limit contributes to optimized fuel atomization and combustion, ensuring the engines run smoothly and efficiently during takeoff and initial climb. This limitation is crucial for safety, as it helps prevent potential engine performance issues that could jeopardize the aircraft's ability to take off safely.