What fuel do planes use?

The rule of thumb is simple: turbine, kerosene; piston, gasoline. An Airbus A320, an ATR 72 turboprop and a turbine-engine helicopter like the H145 all fill up with the same Jet A-1, because all three machines burn fuel continuously in a combustion chamber and don't need the resistance to detonation that a spark-ignition engine requires. A Cessna 172 or a Piper with a Lycoming piston engine, on the other hand, run on avgas, a 100-octane gasoline with a small amount of tetraethyl lead (grade 100LL, dyed blue). Some light-aviation diesel engines, such as those from Continental and Austro, were designed precisely to take advantage of Jet A-1, which is cheaper and available at virtually any airport in the world.

Jet A-1 is the international specification, defined by the ASTM D1655 and DEF STAN 91-091 standards, with a maximum freezing point of −47 °C. Jet A, used almost exclusively in the United States, is identical except for its freezing point, set at −40 °C. Jet B is a kerosene-naphtha blend, more volatile, used in Arctic regions of Canada and Russia where extreme cold makes starting difficult. Armed forces use their own grades: JP-8 is essentially Jet A-1 with a military additive package, and JP-5, with a higher flash point, is the fuel used on aircraft carriers, where the risk of an onboard fire justifies the extra cost.

A single-aisle airliner burns on the order of 2,400-2,700 kg of kerosene per hour in cruise; a long-haul Boeing 777 or A350 burns between 5,500 and 7,000 kg per hour depending on weight. Translated per passenger, a modern long-haul flight at full capacity works out to around 3 liters per 100 km flown per seat. That consumption explains why fuel has come to account for between a quarter and a third of an airline's operating costs, and why each new generation of engines is justified by its reduction in fuel burn.

Sustainable aviation fuel (SAF) is produced from used cooking oils, agricultural waste or, in the future, hydrogen and captured CO₂, and is blended with fossil kerosene without modifying the aircraft: several production pathways are certified, and the maximum authorized blend is 50%. The European Union has required 2% SAF in fuel supplied at its airports since 2025, a figure that will rise in stages through 2050. Hydrogen and batteries are being researched, but remain far from large-capacity commercial aviation.