Hundreds of flights were canceled or delayed at Newark Liberty International Airport over the weekend and again on Monday as shortages of air traffic controllers persists, causing flight disruptions at one of the nation’s busiest airports.

Air traffic control staffing issues continued to cause major delays for passengers flying in and out of the busy Newark airport outside of New York City for an unprecedented sixth day in a row.

On the way: a plan for a new system for the Federal Aviation Administration to manage the roughly 45,000 US flights that carry about 2.9 million passengers each day.