Hundreds of flights due to depart from or arrive at airports on the east coast of the United States were cancelled on Monday after a telecommunications line was severed during works, US officials said.
Bryan Bedford, head of the Federal Aviation Administration (FAA), told reporters that the line was cut near New York, in the neighbouring state of New Jersey.
The incident knocked out radar and radio systems essential for air traffic control, he said.
By about 20:00 BST, Newark Airport, a major hub in the New York area, had recorded 168 cancellations and 97 delays, according to flight tracking website FlightAware.
Philadelphia Airport had 63 cancellations and 189 delays at the same time, the website said.
