The US Federal Aviation Administration (FAA) has not yet determined the cause of a nationwide communications outage disrupting air traffic control operations, with radar and radio frequency systems reportedly experiencing simultaneous failures at multiple facilities, CNN reported.
An airline source told CNN that the FAA "still doesn't know what's going on; it's affecting different facilities in different ways," adding that officials held an emergency call but have not determined the cause of the disruption as nearly 7,000 flights remain grounded, and hundreds more are still in the air.
"Ten minutes ago they were in a crisis call, and there was still no clear answer to the reason," said the source.
CNN aviation correspondent Pete Montagne warned that there is "no real end in sight" to the delays and cancellations spreading across the country under the national ground station.