At times Monday evening, as few as three air traffic controllers per hour were lined up to monitor via radar the planes flying into and out of the airport, the Federal Aviation Administration said.

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.

The Federal Aviation Administration (FAA) continues to grapple with a nationwide shortage of critical aviation personnel, a crisis that’s impacting air travel across the country. At major hubs like Newark International Airport,

We have to fix this, because what you see in Newark will happen in other places across the country,” a top federal official said.