Plane Missed Jet by Half a Mile, FAA Data Shows

The light plane involved in a near-miss with Aeromexico Flight 498 last Saturday passed about half a mile in front of the jetliner, according to recorded radar data released by a Federal Aviation Administration official Thursday.

But like the disaster in the same Cerritos area last August--when Aeromexico Flight 498 collided with a small plane, claiming 82 lives--the air traffic controller guiding the jetliner Saturday did not see the small plane on his radar display screen.

That does not mean the controller erred, according to Jack McMillen, a quality assurance manager for the FAA’s Western Pacific Region. He said the problem instead may lie in the sophisticated electronic computer systems that process the data from radar antennas before they are displayed on radar screens.

FAA officials said state-of-the-art equipment to replace the aging radar systems used by the terminal radar control center at Los Angeles International Airport are expected to reduce these problems in coming months.

A tape-recording of the conversation Saturday between the controller--who has not been identified--and German Basanez, pilot of Flight 498, underscores the differences between what the two men saw.

Controller: “Aeromexico 498. Traffic at 1 o’clock, six miles, westbound, faster than you. A Boeing 727. . . .

Basanez: “OK, we got two traffics. A Cessna and a 727 in sight.”

Controller: “OK. I didn’t see the Cessna.”

Basanez said later that he took no evasive action and neither did the pilot of the other plane, which Basanez thought was a single-engine Cessna 152.

Aeromexico Flight 498 landed safely at Los Angeles International Airport a few minutes after the incident with no injuries to the crew or the 40 passengers on board. Once on the ground, Basanez filed the near-miss report that led to an FAA investigation.

McMillen told an airport news conference Thursday that investigators have not identified the light plane, its pilot or an airfield where it took off or landed.

McMillen said another remaining question is whether the light plane--which lacked the required permission and on-board radar-response equipment--violated FAA regulations by entering the restricted airspace of the Los Angeles Terminal Control Area (TCA).

The TCA is an irregular, 52-by-24 mile swath of airspace normally reserved for the jetliners approaching and taking off from Los Angeles International.

The radar data shows that the Aeromexico jet, properly authorized and equipped, was flying within the airspace when the incident occurred.

The data also shows that the little plane was flying within the TCA, but because the little plane was not carrying the required altitude-encoding equipment, the data does not indicate whether the plane was under the TCA ceiling of 7,000 feet.

FAA officials say that although Basanez’s altitude was 6,200 feet at the time he radioed the controller about the Cessna, he was descending, so his altitude at the time of the incident was probably somewhat higher.

Basanez reported that the Cessna passed by--from left to right--about half a mile in front of him and 300 to 500 feet above him. That means it is possible that the small plane may have been above the TCA ceiling.

The half-mile horizontal separation between the planes that was shown on the radar tapes is about one-third the allowable FAA minimum in the TCA, McMillen said.

McMillen said the continuing investigation will include interviews with the controller and the entire Aeromexico cockpit crew.

McMillen said the investigation is expected to take about six weeks.