1986 Collision brought Mode-C Veil, TCAS Requirement

A low-key ceremony was held Wednesday in Cerritos, CA on the 25th anniversary of a mid-air collision which played a role in changing the way we fly in controlled airspace.

On August 31, 1986, Aeromexico Flight 498, a DC-9, was descending into Los Angeles International Airport after a flight from Mexico City with 64 passengers and crew onboard. According to the NTSB, at 1152 PDT, a Piper PA-28 collided with the tail of the airliner at 6,560 feet MSL, instantly killing its pilot and two passengers, and tearing off most of the tail of the bigger plane. The Piper came down in an unoccupied schoolyard, but the DC-9 hit a residential neighborhood, where the impact and fire which followed destroyed five homes and damaged seven others. All 64 souls aboard the airliner were lost, and 15 people on the ground also died.

Much came of the NTSB's findings. The Piper was on a VFR flight, but had climbed into the Los Angeles Terminal Control Area, which started at 6,000 feet. There was no requirement for the Piper to be in contact with the tower or carry a Mode-C transponder in 1986, and the terminal had no automated warning systems which would have alerted the controller. NTSB determined the controller was distracted by another small plane which had also strayed into the TCA without clearance.

Partly as a result of the Cerritos accident, the FAA instituted a requirement for Traffic and Collision Avoidance Systems (TCAS) in airliners, and created what is now called the "Mode-C veil" in the vicinity of major airports.

In Cerritos, the ceremony was held at 1130 PDT Wednesday, with a moment of silence scheduled for 1152 PDT. It was held in the Cerritos Sculpture Garden, which opened in 2006 with three scultures designed to evoke the image of wings, one each for the airline passengers, the people aboard the Piper, and those who died on the ground.

The flight number 498 is still used by Aeromexico for its service between Monterrey and Mexico City.

FMI: www.airdisaster.com/reports/ntsb/AAR87-07.pdf