Hellish day at US airports after air traffic outage disrupt thousands of flights

Thousands of flights were canceled or delayed in the United States Wednesday following an hours-long nationwide grounding of departures due to an outage of a key computer system used by pilots.

The Federal Aviation Administration said normal operations were being restored, but the early morning halt created knock on effects that were expected to snarl travel throughout the day.

“Normal air traffic operations are resuming gradually across the US,” the Federal Aviation Administration said on Twitter. “The ground stop has been lifted. We continue to look into the cause of the initial problem.”