What is airplane fuel called?

The vast majority of fuel consumed in aviation is refined kerosene, a middle petroleum distillate with a distillation range of roughly 150 to 300 °C. Its international commercial designation is Jet A-1, defined by the British specification DEF STAN 91-091 and the American ASTM D1655, and harmonized in the AFQRJOS document jointly used by major airport fuel suppliers.

In the United States, Jet A coexists with it, practically identical except for one point: its maximum freezing point is −40 °C, compared with −47 °C for Jet A-1. That difference matters on long flights at high altitude, where the outside temperature can be around −60 °C and the fuel in the wing tanks cools for hours. Russia and some neighboring countries use TS-1, with an even lower freezing point, designed for operation in arctic climates.

Kerosene is not chosen for power, but for balance: it has high energy density (around 43 MJ/kg), a relatively high flash point —above 38 °C, much safer to handle than gasoline—, good thermal stability and suitable viscosity to lubricate pumps and injectors. In addition, in many aircraft the fuel acts as a coolant for the oil and hydraulic systems before being burned.

Aviation kerosene does not travel alone. It carries antioxidants, metal deactivators, antistatic additives that prevent charge buildup during high-flow refueling, and corrosion inhibitors that also improve lubricity. In military operations and some civilian aircraft, a fuel system anti-icing additive, FSII, is added, which prevents dissolved water from forming ice crystals capable of clogging filters. Contamination by water and microorganisms is one of the main focuses of quality control on the ramp.

Light aircraft with piston engines cannot burn kerosene: they need aviation gasoline. The dominant grade is 100LL avgas, 100 octane and dyed blue, which still contains a small amount of tetraethyl lead —hence the "low lead"—. It is one of the last transport fuels with lead still in use, and the FAA and industry are working on unleaded substitutes approved for the entire fleet. A growing part of general aviation has migrated to aviation diesel engines that burn Jet A-1.

In the military sphere, NATO uses JP-8, equivalent to Jet A-1 with additional additives; carrier aviation uses JP-5, with a higher flash point (60 °C) for fire safety aboard aircraft carriers.

The industry's new development is SAF, sustainable aviation fuel. It is not a different fuel from the engine's point of view: it is produced from used oils, waste or synthesis with hydrogen and CO₂, certified under the ASTM D7566 standard, and blended with fossil kerosene up to 50% on approved routes, so that the final product meets the same Jet A-1 specification and can be used without modifying aircraft or fuel pumps. The industry is working on certifying 100% blends.