Newark Liberty International Airport is one of the largest hubs of United Airlines, and the congested airport is also the Chicago-based carrier's biggest operational challenge. The company told 1.5 million customers in a note on Thursday that congestion at Newark has eased since it reduced flights there.

United Airlines faces ongoing operational challenges at Newark Liberty International Airport, a key hub for the carrier. Despite flight reductions intended to ease congestion, the airline continues to explore strategic alternatives to maintain revenue and enhance the passenger experience.

Amid dire conditions at the airport, an airline operations crew has had to figure out how to get more than 600 flights a day to take off and land without incident.