The knock-on effect has reached around the world, with disruption within the US expected for days.
What do we know about US air traffic control systems? And how have passengers reacted to Friday's travel chaos?
Democracy is an illusion! It’s become a political system fostered by the élite, for the élite, in order to fool the people that they have a stake in the system. In actual fact, they have virtually none. The whole political system in the modern era, despite having noble beginnings, is now used to benefit the few at the expense of the many. – Mark Alexander, June 29, 2018