Your flight was canceled by the technology outage. What do you do next?

Air travelers became the face of the widespread technology outage Friday as they posted pictures on social media of crowds of people stranded at airports in Europe and the United States.

In the U.S., American Airlines, Delta Air Lines, United Airlines, Spirit Airlines and Allegiant Air had all their flights grounded for varying lengths of time Friday morning. Airlines said the outage hit many systems, including those used to check in passengers and calculate aircraft weight — necessary information for planes to take off.