An evacuation at an FAA facility in Virginia on Monday evening caused delays for hours at Baltimore/Washington International Thurgood Marshall Airport.
BWI grounded all flights around 6:30 p.m. Dulles International Airport and Ronald Reagan National Airport were also affected and were in a ground stop. Flights resumed around 9:30 p.m. and operations were expected to be back to normal by the morning, the Federal Aviation Administration said.
Fumes from nearby construction got into the control room at the Washington Center in Leesburg, Va., which handles high-altitude flights for the region, the FAA said. The control room was evacuated and airborne flights were handed off to air traffic control facilities elsewhere.
By Tuesday morning, the issue had been resolved, BWI Marshall spokesman Jonathan Dean said.
"As of this morning, the airlines are operating their routine schedules," he said.
Around 9 p.m. the local fire department had cleared the air traffic controllers to return to the control room, the FAA said.
According to the tracking website FlightAware, 87 flights were canceled at BWI and 181 flights were delayed.