(CNN) - United Airlines is working with National Transportation Safety Board investigators after one of its planes nearly collided with a US Airways jet over the Pacific Ocean. United Airlines flight 1205 from Hawaii to California was cruising at 33,000 feet on April 25 when the 757's collision alert system sounded.
In order to avoid the nearby jet, the United plane plunged 600 feet in 60 seconds, according to the flight tracking system.
"I'm looking down the aisle and there's hundreds of people in front of me, people start screaming, there's noise of things that weren't secured falling around," passenger Kevin Townsend recalled.
While close calls usually come down to pilot or controller error, disaster is almost always averted because of collision avoidance technology and controllers.
"You're going to run into this situation, unfortunately. Nothing is perfect, I know that's not a comforting answer, but indeed the system worked," an aviation expert said.