Fuel costs for U.S. airlines jumped 78% in April to nearly $6.5 billion , compared with the year before, as the Middle East conflict drives up jet fuel prices, the U.S. Transportation Department said Monday.Airlines’ fuel costs were up 26% over March, and carriers used 2.6% less fuel in April than in March, USDOT said in a monthly report.The cost per gallon of fuel in April was $4.11, up $1.81 from April 2025, USDOT added, a trend that has already had an impact on the sector. Spirit Airlines, an ultra-low-cost U.S. carrier, ceased operations in May, citing rising fuel prices as the reason.Delta Air Lines, United Airlines, American Airlines, and Southwest Airlines account for about 80% of U.S. domestic flights.The International Air Transport Association, which represents more than 370 airlines accounting for about 85% of global air traffic, said in its annual report Sunday that it expects the industry to post a combined net profit of $23 billion in 2026, well below a previous projection of about $41 billion and down from $45 billion in 2025.Average fares for flights with a U.S. origin have risen this year by as much as 31% for domestic trips and 22% for international ones, when compared to the same weeks in 2025, according to KAYAK search data.The Middle East conflict, triggered by U.S. and Israeli airstrikes on Iran, has also forced airlines to reroute flights around closed or restricted airspace, increasing fuel burn and straining already tight capacity.Oil prices have surged on fears of supply disruption, pushing jet fuel prices sharply higher and widening refinery margins, leaving airlines facing a steep jump in their highest cost.IATA expects airlines’ fuel bill to surge to about $350 billion this year from roughly $252 billion in 2025, with fuel accounting for nearly a third of operating costs.