In an interview with CNN, United Airlines CEO Scott Kirby said the biggest issue with canceled flights in Newark is there are more flights scheduled than capacity at the airport, which is adding air traffic, and control is also understaffed.

With the start of summer comes the constant flow of travel traffic, but internal airport issues and the influx of flight cancellations at Newark Liberty Airport have been especially hard.

"Well, what we really want at Newark Airport in particular is to enforce the rules that limit the amount of flights to the number of operations that the airport can theoretically handle...But the other thing we need is to get the air traffic control towers back to full staffing, " said Scott Kirby, CEO, United Airlines.

In other words, there are more flights than the airport can handle.

Friday was the busiest air travel day of the year, as TSA screened 2.4 million people.

Newark was among the worst hit by cancellations with over a hundred flights cut at the United Airlines hub in Terminal C on Monday.

There were 360 flights canceled on Monday, and in total, over 3,000 flights canceled over the course of the weekend.