US air services resume after system outage grounded thousands of flights

Normal air traffic operations are resuming gradually across the US on Wednesday following a technical failure of a key pilot notification system that resulted in the grounding of thousands of flights for several hours.

The Federal Aviation Administration announced earlier in the morning that it suffered an outage of its Notice to Air Missions or NOTAMs, which alerts pilots and other personnel about airborne issues.

The FAA ordered airlines to delay all domestic departures early Wednesday morning, but lifted the ground stop just before 9 a.m. Eastern after several hours.

"Normal air traffic operations are resuming gradually across the US following an overnight outage to the Notice to Air Missions system that provides safety info to flight crews. The ground stop has been lifted. We continue to look into the cause of the initial problem," FAA said in a tweet.

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According to FlightAware, a flight tracking company, so far more than 6,700 flights within, into or out of the US were delayed and more than 1,000 were cancelled due to the system failure.