United is launching new 'fifth freedom' flights. Here's how the rare international routes work and why airlines love them.

Business Insider

22-04-2025

A United Airlines flight from Tokyo to Mongolia? Or Emirates from Mexico City to Barcelona? These routes might seem weird, but are a unique byproduct of decades of globalization and airline evolution — and are especially popular with airline nerds.
Flying across international borders is extremely complex, but a decades-old set of agreements known as the "freedoms of the air" makes it possible. These building blocks of global aviation allow airlines to operate to and from nations other than their own.
The rights, first laid out by the International Civil Aviation Organization (ICAO) in 1944, address geopolitical issues like flying over or landing in another country. The fifth of these is the rarest and gets the most attention.
This allows an airline of one nation to carry passengers between two foreign countries, so long as the route starts or ends in the carrier's home state. Airlines can pick up and drop off passengers in all three nations along the extended route.
Only a handful of carriers, like Singapore Airlines, Emirates, and United Airlines, operate these routes, which can help boost revenue, provide more connectivity for customers, increase aircraft utilization, and capitalize on underused markets.
United announced in April plans to expand its fifth freedom network this year with new routes in Asia to places like Mongolia and Thailand.
United's fifth-freedom routes fly from Tokyo and Hong Kong
United has a long had a presence in the Pacific region, connecting major cities to smaller markets and islands. A handful of these are fifth-freedom routes through Asia.
United flies from Los Angeles and San Francisco to Cebu, Philippines, via Tokyo Narita Airport. The shorter leg uses narrow-body Boeing 737s planes based in Tokyo.
The new route via Narita to Ulaanbaatar, Mongolia, will begin on May 1, and to Kaohsiung, Taiwan, on July 11. This means United can fly its own planes rather than relying on codeshare partners like All Nippon Airways to connect its customers deeper into Asia.
United's SVP of global network planning and alliances, Patrick Quayle, said in an April conference call that the airline is "bullish" on Tokyo expansion because its widebody planes from all over the US efficiently feed the flights that go beyond Japan.
He said this success has prompted the introduction of new fifth freedoms to Ho Chi Minh City and Bangkok starting in October, but through Hong Kong. The Department of Transportation officially authorized the routes on Friday.
They will operate on Boeing 787 widebodies, and United can sell the flights locally or as one-stop flights from the US.
The benefit of fifth-freedom routes
Unique fifth-freedom flying can be efficient for airlines trying to serve destinations that a plane can't reach nonstop, like Emirates' fifth-freedom flights between Mexico City and Dubai via Barcelona.
South American carrier Latam Airlines has a route between Sydney and Santiago, Chile, via Auckland.
Carriers often also make stops on otherwise attainable direct flights because they can capitalize on the high demand on both legs, filling more seats and making more money.
Emirates' fifth freedom from Dubai to New York via Milan, and Singapore Airlines' route from Singapore to New York via Frankfurt are examples of this one-stop strategy.
Adding routes to nearby cities can increase aircraft utilization. Dutch flag carrier KLM flies from Amsterdam to Santiago, Chile, via Buenos Aires, meaning the jet spends less time on the ground in Argentina to instead make more money on a quick hop to Chile.
Airlines may also want to capture demand in smaller or underutilized markets, like United has been doing.
It only competes with Mongolian Airlines and Aero Mongolia to Ulbaanbaatar from Tokyo and flies the sole service between the island country of Palau in Micronesia and Manila, Philippines.