Aviation gasoline is marketed as Avgas 80, 100, 100LL, or 115, each dyed a distinctive red, green, blue, or deeper green so pilots can identify the grade in the tank. All avgas grades are high-octane blends of hydrocarbons that contain tetraethyl lead to prevent knock in spark-ignition engines. Turbine-powered aircraft burn Jet A-1, a clear-to-straw unleaded kerosene manufactured to an international specification, or Jet B, a naphtha-kerosene blend; both incorporate additives like detergents, antioxidants, and biocides. Jet A-1 is defined by a flashpoint minimum of 38°C and a freezing point of -47°C. Sustainable aviation fuel (SAF) can be mixed with Jet A, but it must first be blended to meet the same rigorous standards.
What fuels do airplanes use?
Airplanes use either jet fuel or aviation gasoline, depending on the engine type. Most aviation fuels are used for aircraft propulsion and in gas turbine-powered aircraft. Jet fuel is used globally in turbine engines in civil aviation, and aviation gasoline is usually only used in older piston engines of sports aircraft and small private aircraft. Turbine-powered aircraft burn jet fuel, which is also called aviation turbine fuel, ATF or avtur. The civilian grades are Jet A, common in North America, and Jet A-1, the international standard with a freezing point of -47°C (-52.6°F), and Jet B, a naphtha-kerosene blend, is reserved for extremely cold climates. NATO military aircraft use the same kerosene-based fluid under the name Jet Propellant 8 (JP-8), a formula enriched with special additives.
Piston-engined aircraft require aviation gasoline, abbreviated avgas. The most common grade is 100LL (low-lead), identified by its octane rating and the additive tetraethyl lead that prevents knock and valve wear.
Do airplanes use jet fuel?
Yes, large commercial airplanes use jet fuel. Jet fuel is used in gas turbine-powered aircraft, commercial airliners, and fixed-wing aircraft. Turbine-powered aircraft require kerosene as fuel. Jet fuel is used in turboprop engines, military aircraft, helicopters, and private jets. Jet A1 fuel is used by commercial jets, turbine engines, business jets, and helicopters. Jet A1 is more suitable for international travel as it has a freezing point of -47°C (-52.6°F). Jet A1 has a flash point higher than 38°C (100.4 F). Jet A1 contains static dissipater additives and is dyed blue or green. Small aircraft like piston-engine aircraft, propeller airplanes, gasoline engine aircrafts, and general aviation aircraft like Cessna 172s use AVGAS. Some light aircraft can use automotive gasoline, called mogas. Jet fuel is used for sustained and balanced combustion in rotary engines whereas gasoline is engineered for contained detonations in reciprocating engine motors. Most airplanes don't run on gasoline.
What is aviation fuel made of?
Aviation fuels primarily consist of hydrocarbons refined from crude oil. Nearly all jet fuel is a kerosene-derived middle distillate containing a mixture of C9 to C16 hydrocarbons that boil between 145°C (293°F) and 300°C (572°F). This kerosene base is composed chiefly of paraffins, naphthenes (cycloalkanes) and aromatics, which together account for over 70% of the volume. The fraction is carefully distilled to contain few light or heavy hydrocarbons, giving a distillation range of 175°C (347°F) to 288°C (550.4°F).
Because the exact composition varies with the crude source, a single batch includes more than 260 aliphatic and aromatic compounds, along with polar molecules that carry sulfur, nitrogen, or oxygen atoms. Additives are blended in to safeguard performance: antioxidants, metal deactivators, biocides, static reducers, icing inhibitors and corrosion inhibitors are injected at fuel terminals. Wide-cut military grades like JP-4 cover 60°C (140°F) to 270°C (518°F) and hold roughly 86% saturated hydrocarbons, 13% aromatics and 1% olefins. Civil Jet A-1 meets the same specifications - flash point above 38°C (100.4°F), freezing point -47°C (-52.6°F)-and can now be blended with up to 50% sustainable aviation fuel (SAF) made from biomass, waste or synthetic paraffinic kerosene under ASTM D7566.
Jet A fuel is high-grade kerosene. This kerosene-based petrol is an intricate blend meticulously processed to exigent stipulations. Additives are mixed into the gasoline to avoid freezing, handle static energy, and curb rusting. The mixture possesses great strength and compactness to power heavy aircraft across landmasses. Its preparation orders a heavy flash point for safety, making it less explosive than automobile fuel.
Does airplane fuel have lead?
Jet aircraft used for commercial transport and all turbine-engine aircraft do not operate on leaded fuel, only piston-engine aircraft do. Those engines burn a specialized gasoline called avgas, and avgas still contains tetraethyl lead. The lead is added mainly to raise octane and prevent engine knocking, yet it also aids lubrication and helps cool exhaust valves. Current aviation fuel contains up to 2.12 grams of lead per gallon (0.56 grams per liter) (100LL grade), and 100-octane grades carry as much as 4.24 grams (1.12 grams per liter). This deliberate lead content makes piston-engine aircraft the largest single remaining source of airborne lead in the United States, contributing roughly 470 tons of the metal to the air in 2017 alone.
Because the exhaust carries confirmed lead dibromide particles, the U.S. Environmental Protection Agency has announced that emissions from aircraft operating on leaded avgas cause or contribute to air pollution that endangers public well-being and welfare under the Clean Air Act. Areas near general-aviation airports show raised ambient lead concentrations, and studies have linked lead from small aircraft to soil and drinking-water contamination. Recognizing these risks, the FAA established an Agency performance metric calling for a replacement unleaded aviation gasoline usable by most general-aviation aircraft by 2018. The EAGLE initiative launched in 2022 now aims for a lead-free system by 2030. More than a million pounds of FAA-approved unleaded avgas have already been produced, yet the full transition remains in progress, so leaded avgas continues to be dispensed at many airports today.
How is airplane fuel made?
Jet fuels are typically made by blending and refining various crude oil petroleum distillation products. Crude oil is called liquid petroleum. The oil comprises molecules containing mainly carbon and hydrogen, together with other atoms, mainly sulfur, nitrogen, and oxygen. Different fractions are separated in the distillation tower according to the boiling point. Kerosene is taken as the principal distillation product, then hydrotreated and sometimes hydrocracked. Jet fuel is produced by blending hydrotreated kerosene fraction with hydrocracked kerosene product. Components obtained by distillation are mixed to produce jet fuel meeting specific commercial or military specifications. Additives including metal deactivators, electrical conducting additives, and fuel system icing inhibitors are added at terminals.
Approximately three quarters of that mixture is made from renewable sources like biomass. Approved commercial methods use hydrogen and catalysts to refine biocrude oil into aviation fuel. Catalytic hydrotreating eliminates nitrogen, oxygen, and sulfur from biocrude oil. Cobalt molybdenum is the most effective commercially available catalyst for refining biocrude oil into sustainable aviation fuel. Roughly three quarters of jet fuel mixtures are made from renewable sources, and the remaining quarter must come from fossil fuels. Once jet fuels are made, they are transported through pipelines to terminals. After fuel is stored at an airport, it is distributed to aircraft via pipelines, trucks, or tankers.
The procedure starts with raw petroleum. Crude petroleum is preheated until its several elements divide based on their boiling midpoints. The portion utilized for plane gasoline is a central distillate which is lighter than diesel yet heavier than petrol. The substance takes strict hydrotreating to eliminate contaminations like sulfur, because sulfur is important for both generator operation and environmental security. The resultant treatment of this distillate specifies flight gasoline, and the ultimate output is an extremely refined fuel.
What is the difference between jet fuel and diesel?
The difference between jet fuel and diesel is explained below.
| Attribute | Jet Fuel | Diesel |
|---|---|---|
| Density | Higher | Lower |
| Lubrication Quality | Higher | Lower |
| Freezing Point | Lower | Higher |
| Density | Lower | Higher |
| Viscocity | Lower | Higher |
| Sulphur Content | Higher | Lower |
| Lubricity | Lower | Higher |
| Cetane Number | Lower | Higher |
Jet fuel is designed for turbine engines, whereas diesel fuel is formulated for compression-ignition engines used in vehicles and heavy equipment. Although both originate from refinery middle-distillate pools, diesel is a denser fuel with higher viscosity, giving it higher lubricity than jet fuel. Jet fuel is more expensive than diesel and must respect strict certification and labeling standards, while diesel fuel is cheaper and widely distributed for ground use.
What color is airplane gas?
Aviation fuel comes in a range of hues to help pilots know what is in their tanks. Jet A-1 is essentially colorless with only a clear-to-straw tint, and its hoses are black. Avgas, the gasoline designed for piston engines, is further differentiated by color using fuel dyes. The pilot is visually looking for the type of fuel while draining a sample during preflight, so these dyes are practical, not cosmetic. The most common avgas today, 100 Low-Lead, is dyed a distinctive blue. Older 100/130 avgas is dyed green, and avgas 80, once used in lower-compression engines, was tinted red.
What octane is airplane fuel?
Airplane fuel is high-octane fuel. The most common avgas is 100 octane. Numbers represent octane rating. 100 represents the octane rating of 100. The first number in each case is the aviation lean octane rating, the second number is the aviation rich rating. 100/130 avgas has an octane rating of 100 at the lean settings usually used for cruising and 130 at the rich settings used for take off and other full power conditions. High performance airplane engines have been designed to use 100 octane fuel. 100 octane avgas stops premature detonation in turbocharged engines.
Many general aviation aircraft engines were designed to run on 80/87 octane. Avgas 80 is a low octane fuel and is now mostly obsolete, with 100LL adopted as a compromise. Octanes 87 and 130 are rare today. Avgas 115 has an octane rating of 115 and is used for high performance aircraft. UL91 is lead free fuel with 91 octane rating. G100UL has an octane rating of 100 and is lead free, approved by the FAA.
American and Canadian fuel uses an octane number derived from the average of the RON and the MON numbers. RON is determined by running the fuel in a test engine with a variable compression ratio under controlled 600 rpm conditions. MON is a better indicator of how a fuel will behave under load. 91 AKI fuel provides sufficient detonation margin under normal conditions for eligible aircraft. The extensive testing process required to obtain an STC helps guarantee that 91 AKI fuel provides sufficient detonation margin under normal conditions for eligible aircraft. In Europe the number may be 95 and is no different than 90 octane fuel in America.
Operating aircraft on lower octane than required results in damage from knocking. It is generally safe to operate engines with a higher octane fuel than required as a higher octane number means the fuel can withstand more compression before detonating. Octane rating is the standard measure of a fuel's ability to withstand compression without detonating. Antiknock agents allow higher compression ratios for greater efficiency and power.
Expert behind this article
Jim Goodrich
Jim Goodrich is a pilot, aviation expert and founder of Tsunami Air.
