Both aircraft were inbound to the airport when a loss of separation occurred during their approach for landing

A United flight from San Francisco and a Delta flight from Detroit came within 425 feet of each other in the sky, according to flight radar data. NTSB guidelines say plans should always stay at least five miles apart.

The two flights, United Airlines Flight 1724 and Delta Air Lines Flight 1070 came too close to each other while arriving at the airport.

The close call between the United and Delta flights at the Phoenix airport comes amid an increase in plane near-collisions.

The United and Delta flights were less than a quarter of a mile apart horizontally before the warning devices went off, officials say.

The Federal Aviation Administration is once again looking into a close call at a major U.S. airport, after two passenger jets narrowly avoided a mid-air collision as they attempted to land in Phoenix.

The Federal Aviation Administration is investigating a narrowly missed midair collision between a United flight and a Delta flight at Phoenix Sky Harbor International Airport on Saturday, the agency said.

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

At the same time, a similar alert was set off on a United Flight 1724 from San Francisco, carrying 123 ... according to FlightRadar24. The FAA noted both planes landed safely "after experiencing ...

The FAA has launched an investigation into a loss of separation between two commercial flights in Phoenix Saturday.

A Delta Air Lines plane and a United Airlines aircraft raised alarms when they flew too close to each other while flying into Phoenix on Saturday. The Federal Aviation Administration is investigating the “loss of required separation” incident.

The incident in which a SpaceX rocket broke up after launch demonstrates the challenges the FAA will face as the number of commercial space flights increases.