As the Trump administration begins enforcement of the Real ID Act next month, requiring Americans to carry enhanced identification to board domestic flights, the United Nations is preparing to execute an equally radical — and arguably complementary — transformation of global air travel. The International Civil Aviation Organization (ICAO), a UN agency, is leading what is already dubbed the “biggest [air travel] shake-up” in 50 years — scrapping boarding passes, eliminating check-in, and shifting to a fully digital, biometric system.