Flights bound for the Washington area and some flights from airports in the New York City area that must fly over the Washington region were being delayed or grounded Saturday due to "technical issues" at an air traffic control center in Virginia.
This was reported by the Federal Aviation Administration said.
The agency is investigating an automation problem at an air traffic center in Leesburg, Virginia, FAA spokeswoman Kathleen Bergen said.
The center handles high-altitude air traffic for a region that includes Baltimore-Washington International Thurgood Marshall Airport, Washington's Reagan National Airport and Dulles International Airport.
The FAA said it is directing high-altitude flights around the affected airspace. The problem is not believed to be caused by any accident or hacking.
American Airlines said in a tweet that air traffic control issues are impacting all East Coast flights. The airline is urging passengers to plan accordingly. Laura Nedbal, an American spokeswoman, said its flights from Cleveland to the Washington area were also affected.
Information posted online by the FAA indicated there was a problem with the En Route Automation Modernization computer system, also known as ERAM, at the Leesburg center.
The FAA finished installing the troubled computer system in the last of 20 high-altitude traffic control centers earlier this year. The completion was years behind schedule.
Miller Roberts, 40, of Dallas was trying to fly from Baltimore to Kansas City to set up a robotics display at the Missouri State Fair but was caught in a flight delay for more than four hours.
Roberts said he boarded a Southwest Airlines flight that was supposed to take off at 10 a.m., but he was still sitting on the plane, waiting after 2 p.m. But he said his fellow passengers were taking the delay in stride.
"I think everyone realizes this is out of our control," he said.
Roberts said he only heard one groan after the pilot's last announcement saying it would be another hour before they had an update on their flight status. The plane returned to the gate after the problems became clear, and passengers were allowed to get on and off for food or restroom breaks.