United Airlines Flight 663

United Airlines Flight 663 was a "minor international incident" in 2010 involving a Qatari diplomat on the leg of a United Airlines flight from Ronald Reagan Washington National Airport (Washington, D.C.) to Denver International Airport (Denver, Colorado). The diplomat prompted a mid-air terrorism alert after smoking in the aircraft lavatory, which led the Qatari government to recall him two days later.

Source: Wikipedia — United Airlines Flight 663 (CC BY-SA 4.0)