The airline told the Sun the e-mail was sent to passengers who have upcoming flights to or through Newark’s airport, as well as its MileagePlus

The crucial travel hub for United is still struggling to recover from air traffic control glitches that have already disrupted hundreds of flights.

Caught in the middle of the issues at Newark is United Airlines, which is the most active airline at the New Jersey airport. While the problems lie with the FAA system, the airline is where people often aim their frustrations over cancellations and delays.

United Airlines anticipates a reduction in flight disruptions at Newark Liberty International Airport as runway construction nears completion. The airline has been canceling flights to manage reduced capacity and plans for potential schedule cuts pending FAA decisions.

United CEO Scott Kirby tried to allay trepidations travelers might have about flying in and out of Newark Airport as issues mount.

"We've turned the corner, and we have the commitment," United Airlines CEO Scott Kirby said of reforms to the Federal Aviation Administration.

Three incidents at Newark have shaken the public. Meanwhile, the FAA is understaffed. Here's what the Trump administration wants to do about it.

One air traffic controller (ATC) and a trainee will operate every flight in and out of Newark between 6.30pm-9.30pm — despite 15 staffers being the standard requirement for a shift.