The planes, carrying more than 350 people, experienced "a loss of required separation" while preparing to land at the same Phoenix airport, the FAA said.

The FAA said it is investigating after a Delta Air Lines flight and United Airlines flight experienced 'a loss of required separation' while heading inbound to Phoenix Sky Harbor International Airport.

The Federal Aviation Administration is investigating after a United Airlines flight and a Delta Airlines flight had a near-collision over Phoenix on Saturday.