investigation was unable to determine if the thrust reversers were intentionally activated and later deactivated. It was important for the investigation to establish the position of the mechanical activators on the flaps, since their lack of deployment was a fundamental cause of the accident. A special investigation was carried out to establish what had happened with the flaps. The extended flaps alter the aerodynamic characteristics of the aircraft, giving the aircraft lift to get off the ground at a lower speed over a shorter distance than would be possible without flaps. This is why in practice, there are no runways that would allow the take-off of medium- to large- size aircraft without flaps. The main finding within the remains of the plane was that all of the examined flaps' worm gear operators were in the unwound position indicating that the flaps were not deployed. This tallies with the flap command in the cockpit that was also in the no-flaps position, that the readings at the FDR indicate they were retracted, and that the flap lights were off indicating that they were not activated. The alarm sound recorded by the CVR indicated that there was a problem with the departure configurations. The recording showed that at the time of departure the flaps were not in the correct position for lift-off. A study was performed on the electrical circuitry to determine the position of the electrical breakers on the take-off warning system. Also, a study was performed on the slat indicator lights' filaments. The indicator lights were found to be off, the only fire alarm was off, and the main warning indicators (Master Caution) were found on. The latter could be activated by any one of a long list of possible faults resulting in the destruction of the aircraft. Causes According to the investigative commission, the immediate cause of the accident was "that the flight crew of LAPA flight 3142 forgot to extend the wing flaps to initiate take-off, and ignored the alarm that advised them of the error in configuration for take-off." Contributing factors The report of the JIAAC cites the following factors as contributing to the accident: Lack of crew discipline, who did not make the logical reaction of aborting take-off and checking for errors when the alarm sounded as the engines started and as it continued to sound until the take-off attempt. Excess conversations irrelevant to the flight, and