A major shortage of air traffic controllers cause at least 56 flight cancellations as airlines scramble to adjust schedules. ––– Subscribe to ABC News on YouTube: https://abcnews.visitlink.me/59aJ1G ABC News is your daily source of breaking national and world news, exclusive interviews and 24/7 live streaming coverage. Download the ABC News app for the latest headlines and alerts: https://abcnews.go.com/devices Watch 24/7 coverage of breaking news and live events on ABC News Live: https://www.