crashing into the backyard of a house at 13426 Ashworth Place, where it exploded on impact. The explosion scattered the DC-9's wreckage across Holmes Avenue and onto Carmenita Road, destroying four other houses and damaging seven more. All 64 passengers and crew on board the DC-9 and 15 people on the ground were killed, and a fire added to the damage. Passengers and crew Thirty-six of the passengers were citizens of the United States. Of the 20 Mexican citizens, 11 lived in the U.S. and nine lived in Mexico. One Salvadoran citizen lived in Islip, New York. Ten of the passengers were children. 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 without the required clearance. The TCA included a triangular slab of airspace from 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 terminal control areas, the FAA required that all jets in U.S. airspace be equipped with a traffic collision avoidance system (TCAS) 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