Since Russia’s invasion of Ukraine a year ago, carriers from Europe, Canada and North America have skirted around the country, making lengthy detours to avoid flying in its airspace. Now, CEOs are worried that those added miles put them at a disadvantage to Asian carriers who still use Russia for their long-haul flights.

“If you’ve got a Chinese carrier that is flying over Russia, they’ve got an unfair advantage over us,” Ben Smith, CEO of Air France-KLM, told the Financial Times on Friday. Smith complained that skipping Russian airspace added “three hours in flight time” for a plane traveling from Paris to Seoul.

Before Russia’s invasion of Ukraine, airlines often flew over Russia to connect Asia with destinations in Europe or North America. But Russia barred many Western airlines from using its airspace last February, in retaliation for governments in Europe and North America banning Russian airlines from flying over the West.

European, Canadian and U.S. airlines are thus forced to fly different routes to avoid Russia. Longer flights burn more fuel, meaning higher costs and emissions. Longer flights can also upend tight flight schedules, as well as breach limits on working hours for flight crew.

Yet carriers from several non-Western countries, including China, continue to fly over Russian airspace, allowing them to offer faster and cheaper flights to European and North American destinations.

European airlines are now worried that they’ll lose out on the wave of Chinese rebound travel, as Beijing reopens from years of COVID-era isolation. (Chinese tourism plummeted after the country required all international arrivals—including returning Chinese tourists—to spend weeks in quarantine.)

“It will be very hard to make secondary cities of China profitable in terms of flying,” Topi Manner, CEO of Finnair, said to the Financial Times last week. The closure of Russian airspace has hurt Finnair, kneecapping an effort by the airline to turn Helsinki as a hub for flights connecting northern Asia with Europe.

The European Union says it's powerless to resolve the discrepancy. “There are no measures that can be applied,” Henrik Hololei, the European Commission’s director general for transport and mobility, said at a conference in mid-January.

Detours have already forced airlines to suspend, or even permanently cancel, routes. Last year, Virgin Atlantic blamed the closure of Russian airspace for its decision to close its operations in Hong Kong.

The polar route

Chinese airlines aren’t the only ones still using Russian airspace. Air India, for example, flies over Russia for its direct flights from India to the United States. Middle Eastern airlines, like Emirates, also continue to fly over Russia on their North American routes. Several of these carriers also serve Russian destinations.

Some Asian airlines, like Korean Air or Japan Airlines, stopped flying over Russia despite not being explicitly barred from doing so. Detours mean these airlines face the same issues with weight and flight time as their Western peers. In October, an Asiana Airlines flight from New York to Seoul had to stop in Tokyo to avoid breaching maximum flight hours for its crew.

The added hassle of avoiding Russia has already pushed one Asian airline to start flying over the country again. After initially avoiding the country, Cathay Pacific, Hong Kong’s flagship airline, resumed using Russian airspace in November.

The airline said the so-called polar route, which flies over Siberia and the Arctic, was “safe, direct and the fastest experience” for those flying between Hong Kong and the U.S. The Hong Kong airline was the first to use Russian airspace to fly between Asia and North America, first flying the polar route in 1998.

This story was originally featured on Fortune.com

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