NEW YORK (AP) — A looming jet fuel shortage in Europe and Asia sparked by the Iran war and the effective closure of the Strait of Hormuz could further upend world travel within weeks if oil doesn't start flowing again soon — meaning higher airfares and flight cancellations as the summer travel season approaches.
In an exclusive Associated Press interview Thursday, International Energy Agency Director Fatih Birol said Europe has "maybe six weeks" of remaining jet fuel supplies and said the global economy faces its "largest energy crisis."
In general, some European countries hold several months' worth of jet fuel inventory at a time, according to an IEA report released this week.
Jet fuel — a refined kerosene-based oil product — is airlines' biggest cost, making up about 30% of overall expenses, according to the International Air Transport Association. And jet fuel prices have roughly doubled since the war began. Shortages could start next.
"Every passing day that the Strait of Hormuz remains shut, Europe is edging closer to supply shortages," said Amaar Khan, head of European jet fuel pricing at Argus Media. "The strait accounts for around 40% of Europe's jet fuel imports, but no jet fuel has passed the strait since the war broke out."
Airline officials have largely reacted with caution, acknowledging potential fuel issues but working to reassure customers. Still, some carriers have already passed costs on to consumers by increasing fees for baggage and other add-ons, embedding costs into ticket prices, or raising fuel surcharges.
A handful of airlines already are cutting flights. Experts say other parts of air travel — such as scheduling flexibility and routes — would likely be impacted.
Here's a look at how jet fuel supplies work and how consumers might see effects.
How does jet fuel get to the plane?
Jet fuel is made from crude oil at refineries, which also create gasoline and diesel.
Airlines generally buy jet fuel from refineries or fuel companies, similar to drivers buying gasoline from stations, but on a much larger scale. Jet fuel travels on ships and through pipelines and is stored by airlines at airports.
Purchasing is handled by airlines. If fuel supplies are running out in a region, that doesn't necessarily mean there will be no flights. Some airlines might have more stored than others.
But remaining flights are likely to be expensive, reflecting fuel costs.
Larger airlines have advantages in regions with shortages. They have the financial means to deal with high prices, said Jacques Rousseau, managing director at financial firm Clearview Energy Partners.
In Europe, a number of countries are now relying on less than 20 days of coverage in their fuel supplies, according to this week's IEA report. Supplies haven't dropped below 29 days since 2020, the report said.
If that falls under 23 days, physical shortages may emerge at some airports, resulting in flight cancellations and lower demand, the report warned.
Which regions could feel pain?
Asia-Pacific countries are the most reliant on oil and jet fuel from the Middle East, followed by Europe, Rousseau said.
Most of Europe's jet fuel is produced by European refiners, but about 20-25% of its supply is missing because of the war, Rousseau said.
To fill some gaps, the U.S. has increased its exports of jet fuel to Europe considerably, sending about 150,000 barrels per day in April, or about six times the normal level, Rousseau said.
Availability of jet fuel is less of an issue in the U.S., a major oil producer, he added.
"I tell my kids ... we're not so much going to run out of supply," Rousseau said. "It's just going to cost more here, whereas in different parts of the world you could actually get to a point where there's just no fuel."
How much is the world supply of jet fuel lagging?
The world is losing 10 million to 15 million barrels of oil a day due to the closure of the Strait of Hormuz, said Pavel Molchanov, senior investment strategist at investment firm Raymond James & Associates.
"There are exactly the same refineries in exactly the same places in Asia and Europe, but if there is not enough oil for those refineries to operate, it's going to lead to physical supply disruption," he said.
Even though the IEA has released 400 million barrels of oil from members' emergency reserves, that won't help in the short term, he added.
"It could take until the end of the year to get all of those barrels onto the market," he said.
How will my travel be affected?
Christopher Anderson, a professor of operations, technology and information management at Cornell University, said travelers should prepare for more than just higher airfares.
"This is no longer just a fuel-price story. For airlines, it is now a network-planning story," he said. "Higher fuel costs matter, but so do longer routings, reduced scheduling flexibility and greater uncertainty about what demand will look like even a few weeks out."
Travelers might see "a market with later booking patterns, more schedule volatility and fewer low-fare options if this disruption lasts into the core summer season," he said.
What are airlines doing?
Dutch airline KLM and U.K. budget carrier easyJet told AP they weren't experiencing current fuel shortages, without commenting further on the IEA's warning.
Still, both airlines are among those that have seen higher costs eat into their budgets.
On Thursday, KLM said it would cut 160 flights next month — about 1% of its total European routes. The airline cited "rising kerosene costs" and said a limited number of flights are "no longer financially viable to operate."
In a Thursday update, EasyJet said it expects to see a pretax loss of 540 million to 560 million pounds (about $731 million to $758 million) for the first half of the 2026 fiscal year. Still, CEO Kenton Jarvis said demand remains strong overall — noting that Easter travel was easyJet's busiest ever for that holiday period.
Lufthansa said Thursday that labor disputes and high fuel prices are forcing it to immediately shut down feeder airline CityLine, earlier than planned, and take its 27 older, less fuel-efficient planes out of service. The decision accelerates a shutdown that had been expected for next year.
U.S. carrier Delta Air Lines — which frequently flies to European destinations — said on Thursday that it was "aware of the potential jet fuel supply issue" on the continent and monitoring the situation. Delta, which bought a refinery in Philadelphia in 2012 to manage its largest expense, said it doesn't expect any "near-term impact to our operations."
How are prices affected?
Other airlines have sounded the alarm about rising fuel prices, with some already passing along new costs to travelers, often embedded into ticket prices and add-on fees.
U.S. carriers Delta, United, American Airlines, Southwest Airlines and JetBlue have all increased checked baggage fees, for example, in recent weeks.
WATCH: The hidden reasons airlines are raising bag fees
United CEO Scott Kirby said in a recent memo to staff that if fuel prices stay elevated, it could add $11 billion in annual costs. "For perspective," Kirby wrote, "in United's best year ever, we made less than $5B."
Meanwhile, Hong Kong's Cathay Pacific recently bumped fuel surcharges by roughly 34% across all routes, while Air India added up to $280 in fees to some flights earlier this month. Emirates, Lufthansa and KLM have also adjusted fees or fares to keep pace with the price volatility.
AP writer David McHugh in Frankfurt, Germany, contributed to this report.