Airline ‘Fifth Freedom’ Routes: What They Are and How They Work

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…