United Airlines executives are trying to reassure their customers it is safe to fly at Newark Liberty International Airport, despite widespread cancellations and air traffic control issues continuing to spark concerns.

Technology and staffing problems have plagued the airport, one of the nation’s busiest hubs. Officials say they are trying to resolve the issues, but concerns remain.

The shortage on Monday forced the F.A.A. to delay flights to the busy airport for up to nearly seven hours, the latest problem to plague the airport.