At what temperatures is Jet-A most susceptible to ignition?

• A. -50 to 30F
• B. 0 to 50F
• C. 200 to 300F
• D. 100 to 165F

Answer: (D)

Ignition of Jet-A depends on how much fuel vapor is present in the air. As temperature rises, more fuel evaporates, creating a combustible vapor–air mixture that can be ignited by a spark or flame. There’s a mid-range temperature window where this vapor is enough to form a flammable mixture but not so hot that other hazards dominate. That’s roughly 100–165°F. In this range, the fuel vapors readily mix with air and an ignition source can cause ignition. At much colder temperatures, there isn’t enough vapor to sustain ignition, and at very high temperatures the ignition scenario shifts toward different mechanisms, with autoignition occurring at still higher temperatures. So the 100–165°F range is the point where Jet-A is most readily ignitable by an ignition source.