The lack of just a dozen air traffic controllers has contributed to danger, chaos, and waves of delays and cancellations at Newark Liberty International Airport. Yet the Federal Aviation Administration — despite employing about 14,

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.

Over the past two weeks, several equipment outages at the Philadelphia-based air traffic control center that guides planes to and from Newark Liberty International Airport, have raised questions on just how safe it is to fly at one of the nation’s busiest airports.