Aeroméxico Flight 498

Investigation and aftermath

The U.S. National Transportation Safety Board (NTSB) investigation found that the Piper had entered the Los Angeles Terminal Control Area (TCA) airspace (now Class B Airspace) without the required clearance. The TCA included a triangular slab of airspace from 6000 to 7000 ft of altitude, reaching south to across the Piper's intended flight path. The Piper could legally fly beneath this airspace without contacting air traffic control (ATC), but instead climbed into the TCA. The ATC had been distracted by another unauthorized private flight, a Grumman AA-5B Tiger, entering the TCA directly north of the airfield, which also did not have clearance.

The Piper was not equipped with a mode C transponder, nor was one required, which would have indicated its altitude, and LAX was not equipped with automatic warning systems. Neither pilot appeared to have attempted any evasive maneuvers, because neither pilot sighted the other aircraft, although they were in visual range. When an autopsy revealed significant arterial blockage in Kramer's heart, public speculation arose suggesting that he had experienced a heart attack that incapacitated him and led to the collision, but further forensic evidence discounted the theory and Kramer's error was determined to be the main contributing factor to the collision.

As a result of this accident and other near-midair collisions in TCAs, the FAA required that all large commercial jets in U.S. airspace be equipped with a traffic collision avoidance system and required that light aircraft operating in dense airspaces be equipped with mode C transponders, which can report their altitude.

A jury ruled that the DC-9 bore no fault, instead deciding that Kramer and the FAA each acted equally negligently and bore equal responsibility. Federal Air Regulations 14 CFR 91.113 (b) require pilots of all aircraft to maintain vigilance to "see and avoid" other aircraft that might be on conflicting flight paths.

The United States Court of Appeals for the Ninth Circuit applied the Supreme Court of California's ruling in Thing v. La Chusa to extend recovery for negligent infliction of emotional distress to Theresa Estrada, whose husband and two of four children were killed on the ground as the result of the crash. In the television documentary Mayday, Estrada reported that she saw the explosion from a distance; Thing requires that the person be at the scene and aware of the injury being caused to the victim. She arrived minutes later, with her home consumed by fire and surrounded by burning homes, cars, and aircraft debris. In a separate trial on damages, the Estrada family was awarded a total of $868,263 in economic damages and $4.7 million in noneconomic damages, including $1 million for the negligent infliction of emotional distress.