Thursday was a tough day to fly in or out of Newark Liberty International Airport.

According to the Federal Aviation Administration, more than 400 flights were delayed as of Thursday evening and more than 200 were canceled.

The FAA says that a shortage of air traffic controllers is one reason for the slowdown. The other issue is that crews are resurfacing one of three runways at the airport.

A steady flow of travelers has been checking departure and arrival boards inside Terminal B to see the status of their flights and hoping they aren’t canceled. Some were on their phones and computers, looking to rebook flights outside of Newark.

“We’re trying to figure it out. I’ve got to make some calls, figure out an alternative flight. Maybe get up to Laguardia or JFK in time,” said traveler Ben McArthur. “Tee time is tomorrow morning, so if we can get there tonight, that’s all that matters.”

McArthur says his 11 a.m. flight to Florida was delayed until 4 p.m.

Others who saw their flights canceled have been able to rebook without being charged any extra fees.

Thursday’s delays follow a ground stop on Monday caused by what the FAA says was an equipment issue. It left many travelers circling overhead for hours or some stranded in other cities.