NTSB Probable Cause

THE FAILURE OF THE LOS ANGELES AIR TRAFFIC FACILITY MANAGEMENT TO IMPLEMENT PROCEDURES THAT PROVIDED REDUNDANCY COMPARABLE TO THE REQUIREMENTS CONTAINED IN THE NATIONAL OPERATIONAL POSITION STANDARDS AND THE FAILURE OF THE FAA AIR TRAFFIC SERVICE TO PROVIDE ADEQUATE POLICY DIRECTION AND OVERSIGHT TO ITS AIR TRAFFIC CONTROL FACILITY MANAGERS. THESE FAILURES CREATED AN ENVIRONMENT IN THE LOS ANGELES AIR TRAFFIC CONTROL TOWER THAT ULTIMATELY LED TO THE FAILURE OF THE LOCAL CONTROLLER 2 (LC2) TO MAINTAIN AN AWARENESS OF THE TRAFFIC SITUATION, CULMINATING IN THE INAPPROPRIATE CLEARANCES AND THE SUBSEQUENT COLLISION OF THE USAIR AND SKYWEST AIRCRAFT. CONTRIBUTING TO THE CAUSE OF THE ACCIDENT WAS THE FAILURE OF THE FAA TO PROVIDE EFFECTIVE QUALITY ASSURANCE OF THE ATC SYSTEM. (NTSB REPORT AAR-91/08)