WASHINGTON (AP) _ Airline passengers trying to travel Friday found canceled flights and long delays at some airports as the nation's aviation system sought to recover from the huge blackout.
US Airways canceled its popular shuttles between Washington and New York all morning. The Delta Airlines shuttle was back up by midmorning.
At New Jersey's Newark International Airport, several hundred people were lined up at the American Airlines ticket counter in the morning.
Nakisha Nesmith, 24, of Los Angeles, flew in Friday morning from Brazil. Her plane was diverted to Newark from New York's John F. Kennedy International Airport, and she missed her connection to the West Coast.
``Now, we have to wait on this line to see when we can get out of here. We have no idea when we're leaving,'' Nesmith said.
The blackout that struck about 4 p.m. Thursday caused the biggest problems at six major airports: Newark, Cleveland, Toronto, Ottawa, and New York's Kennedy and LaGuardia. Most flights were halted for several hours, backing up air traffic nationwide and in Canada.
The Federal Aviation Administration and the airlines said they did not know how many flights overall were affected.
The problems at the six airports were not related to air traffic control. Rather, there was no power to run the metal detectors and X-ray machines at security screening checkpoints.
Planes already in the air were allowed to land, directed by air traffic controllers operating with emergency power. That also allowed controllers to continue to direct flights to and from other airports.
FAA spokeswoman Laura Brown said the system slowly was returning to normal Friday.
``They're trying to catch up,'' Brown said, referring to airlines ``They have equipment all over the place.''
Meantime, Amtrak resumed limited service between Washington and New York, but service between New York and Boston remained on hold.
In New York, officials said there would be no morning or evening rush-hour service on the city's subways. Workers who come in from the suburbs were warned of similar disruptions on the two commuter lines, the Long Island Rail Road and Metro-North.