A FedEx aircraft aborted landing to avoid a Southwest Airlines passenger jet that was mistakenly cleared for the same runway

• A FedEx aircraft aborted its landing to avoid a Southwest Airlines jet on Saturday during heavy fog.
• Both were mistakenly cleared for the same runway at Austin Bergstrom International Airport. 
• "The pilot of the FedEx airplane discontinued the landing and initiated a climb out," said the FAA.

A FedEx aircraft had to abort a landing in heavy fog to avoid colliding with a Southwest Airlines passenger jet on the same runway.

The crew operating FedEx's Boeing 767 had to execute a "climb out" in order to avoid landing on top of Southwest's Cancun-bound Boeing 737 at Austin Bergstrom International Airport shortly after 6 a.m. on Saturday.

It's being investigated by both the Federal Aviation Administration, or FAA, and the National Transportation Safety Board.