Source: US Energy Information Administration, U.S. Gulf Coast Kerosene-Type Jet Fuel Spot Price FOB, USD per gallon.
Fuel accounts for about 40% to 50% of air operating costs of a single flight, depending of the type of plane used (economies of scale and fuel efficiency are directly related). Since 2000, the airline industry is facing an environment characterized by much higher fuel prices and volatility. Between 2005 and 2016, fuel prices could vary between 20% and 35% of the operating expenses of an airline. While during the 1990s, jet fuel prices were very stable, the beginning of the 21st century is marked by a surge or prices as well as large fluctuations. In the 2010s, jet fuel prices stood at 6 times the level seen in the 1990s. This makes the long term planning of air operations more complex, with the priority in aircraft design focusing on fuel efficiency.