BRUSSELS — Summer getaways are at risk of disruption as airlines across Europe brace for a jet fuel crunch that threatens peak travel season.

There’s no crisis yet, but concern is mounting that if Iran’s effective closure of the Strait of Hormuz continues, airlines will resort to widespread route cuts, cancellations and fare hikes.

“May is going to be very difficult because you do not have the capability to replace the lost [jet fuel] volumes from the Strait of Hormuz,” said George Shaw, senior oil analyst at data platform Kpler.

With the U.S.-Israeli war on Iran in its second month, Asian airlines are starting to slash flights, and the same may happen in Europe in the coming weeks.

“If the war continues we do run the risk of supply disruptions in Europe in May and June,” Ryanair CEO Michael O’Leary told Sky News, adding: “There’s a reasonable risk at some low level of maybe 10, 20, 25 percent of our supplies might be at risk.”

That level of kerosene cuts “would mean forced capacity cuts on services within, to and from Europe,” Barclays’ head of European transport equity research, Andrew Lobbenberg, said in a research note.

The International Energy Agency is urging people to “avoid air travel where alternative options exist.”

The war unleashed Feb. 28 by Donald Trump and Israel on Iran has rippled through aviation. The immediate impact was a collapse in flights through key Gulf hubs like Dubai and Qatar. That left thousands stranded and upended connections between Europe and Asia.

When Iran retaliated by closing the Strait of Hormuz, the price of kerosene jet fuel soared, doubling to about €1,500 per metric ton compared to before the war.

Running on empty

Now the big fear is supply.

The most acute worry is at Heathrow. The U.K. imports about 50 percent of its jet fuel from the Gulf, and the final tanker carrying kerosene from the Gulf loaded before the war is on its way to Britain.

Other European airports are keeping a nervous eye on their fuel supplies, but so far there is no emergency.

Lufthansa spokesperson Sandra Courant said: “Currently, we do not see any kerosene shortages at any Lufthansa Group hubs (including Frankfurt).”

There are early signs that Europe’s airlines are starting to react.

Lufthansa CEO Carsten Spohr on Tuesday reportedly presented contingency plans to his staff. Depending on how much worse the situation gets, the airline could temporarily ground either 20 or 40 planes — about 5 percent of its seating capacity.

SAS Scandinavian Airlines has canceled about a thousand flights due to high fuel prices, while Air France-KLM has announced a ticket surcharge on long-haul flights and Finnair said its prices will increase because of the war.

“Passengers are seeing higher ticket prices and added fuel surcharges, and some routes are being modified to avoid certain airspaces, which increases costs further,” said Wouter Dewulf, air transport economist at the University of Antwerp.

“There have been a few isolated cancellations and schedule adjustments, but nothing that suggests widespread disruption across Europe at this stage,” Dewulf added. But “if high prices and logistical constraints continue for another one to two months, the pressure will increase … airlines may start reducing flight frequencies, cutting less profitable routes, and introducing more targeted cancellations.”

For now, people with tickets are still relatively safe as EU air passenger rights rules discourage last-minute cancellations.

“If carriers decide to cancel because of the [jet fuel] price increase, it is a commercial decision not depriving consumers from compensation rights,” said Steven Berger, senior legal officer for the European Consumer Organization. Compensation ranges from €250 to €600, which airlines must pay to passengers in addition to a ticket refund when they cancel a flight at short notice.

However, people with tickets for summer holidays can’t rest easy. If carriers cancel flights at least 14 days before the departure date, they don’t have to pay compensation, Berger added.

From bad to worse

Iran’s Hormuz blockade is creating a global squeeze that makes it very difficult for European airlines to avoid.

In normal times, global energy flows help dissipate local shortages. Europe has often turned to Asia for jet fuel during periods of peak demand, but now every part of the world is hoarding kerosene.

“China has an export ban of oil products in place,” Kpler’s Shaw said, while South Korea and other East Asian countries also “went into a protectionist mode.”

European aviation “just doesn’t have alternative sources of supply,” he added, noting that the U.S., a new refinery in Nigeria and other smaller exporters may provide some jet fuel, but those volumes are unlikely to be enough to meet continental demand.

There is also hope in the industry that Trump ends the war and the crisis resolves itself, although the weeks with no tanker traffic will take a long time to work out.

Even if the war were to stop today, “the time that it would take to get normalization of flows means that Europe would still be in a very tricky situation,” Shaw said, noting the flow of fuel from Kuwait to Europe would take six weeks to resume.

“The real tipping point would come if physical fuel shortages began to appear at European airports,” Dewulf said. “That remains a risk rather than a reality today, but it would quickly translate into broader disruptions if it materializes.”

For now, airports say they aren’t facing a fuel crunch.

“An overwhelming majority of airports (86 percent of members who responded to our survey) are for the moment reporting jet fuel stocks managed by suppliers in line with normal levels — with some even reporting higher levels,” said Olivier Jankovec, director general of airport lobby ACI Europe. “Only 10 percent are reporting a potentially high risk of jet fuel shortage.”

But travelers can’t rest easy, as Jankovec warned of “a significant degree of uncertainty in the current situation.”