Incident
At approximately 1140 Pacific Daylight Time, a Piper PA-28, registered as N4891F, departed Torrance, California, on a visual flight rules flight to Big Bear, California. After takeoff, the pilot turned eastbound toward the Paradise VORTAC with the transponder set to squawk 1200. At the same time, Aeromexico Flight 498, a DC-8 with Mexican registry XA-JED, was on arrival, receiving northbound vectors from a Los Angeles Approach Controller (AR-1 controller) for an instrument landing system approach to Los Angeles International Airport.
At 1151:04, the controller instructed Flight 498 to reduce speed to 190 knots and descend from 7000 to 6000 feet. During this time, the controller was coordinating other traffic and providing radar advisories but did not see a display for N4891F on his scope. At 1152:09, N4891F and Flight 498 converged and collided at approximately 6560 feet, then fell to the ground.
Investigation Findings
An investigation revealed that N4891F had inadvertently entered the Los Angeles Terminal Control Area (TCA) and was not in radio contact with air traffic control. The LAX Terminal Radar Approach Control (TRACON) was not equipped with an automatic conflict alert system, and the analog beacon response from N4891F's transponder was not displayed due to equipment configuration. The position of N4891F was displayed by an alphanumeric triangle, but the primary target was not displayed due to an atmospheric inversion.