Several times over the last year, Newark controllers lost radar or radio service, leaving them unable to talk with planes they were tracking.

A deadly midair collision in January between a military helicopter and a commercial airliner, and several crashes since, have prompted officials to focus on fixing the nation’s outdated air traffic control system and hiring more controllers.

Some controllers are on a 45-day “trauma leave" as Newark Liberty International Airport experiences ongoing staffing shortages.

Newark Liberty International Airport has worked through delays and cancellations for nearly two weeks, and four main reasons are the cause.