After a pandemic, loss of income, and pilot and staffing shortages, you’d think the airlines have seen it all in the last year.

Now there’s a new worry.

U.S. carriers say there is a fuel shortage afoot, mostly at small to mid-size airports in the west, forcing them to add refueling stops or fly fuel into locations where the supply is tight.

Delta Air Lines said Reno, Nevada, is the most affected location as pipelines have been devoting more space to gasoline and diesel and less to jet fuel during the pandemic. Nevada politicians worry that the situation could limit the flow of tourism dollars.

But American Airlines has actually asked pilots to conserve as much fuel as they can during trips because of a potential crisis.

The delay has also been due to a lack of truck drivers, trucks and fuel supply.

"American Airlines station jet fuel delivery delays initially affected mostly western U.S. cities, but are now being reported at American stations across the country. Delivery delays are expected to continue through mid-August," John Dudley, managing director of flight operations for American, told pilots in a memo, which was reviewed by CNBC .

The airline said flights will carry additional fuel into airports affected by shortages, a procedure known as tankering or add fueling stops.

"As our country continues to face multiple challenges, let's work together as a team to operate reliably, safely and as efficiently as possible," Dudley wrote. He asked that pilots to use fuel-saving strategies such as taxiing with a single-engine.

"We have been and continue to be in communication with federal authorities and pipeline operators to address this jet fuel capacity issue," Airlines for America, which represents most large U.S. carriers, said in a statement.