A large Delta 737 from Phoenix and a small regional jet approaching the runway from different directions and at different altitudes came within two miles of each other, well within the usual three-mile safety zone.
The FAA, which is investigating the incident, said the confusion happened when an air traffic controller's headset began to give out, broadcasting intermittently. The pilots were unable to hear all the instructions.
"Obviously that's not a desirable situation and perhaps even more insidious is the fact the pilot may not know what he or she isn't hearing," said Steve Wallace, a former FAA director of accident investigation.
The FAA says there was no threat of a collision, saying both pilots could see each other's planes. The larger Delta 737 eventually passed above and both planes landed safely.
This latest incident comes just three days after another scare in the skies when three planes nearly collided over the nation's capital. A commute airliner took off in the wrong direction from Washington. D.C.'s Ronald Reagan Washington National Airport, heading into the path of a second jet cleared to land on the same runway. An alert air traffic controller saw the confusion and ordered the landing pilot to change course.
Safety experts say it's been 34 years since the last mid-air collision involving U.S. airliners.