controlled the flight plan. Having seen the good weather conditions, the captain selected Aeroparque Jorge Newbery as the alternative airport and decided on the fuel requirements for the flight. The first officer went to the aircraft and the captain followed him shortly after. The whole briefing lasted approximately ten minutes. There were no unusual incidents during the briefing. There were no comments or attitudes outside the norm from either of the two pilots during the briefing. According to the dispatcher, the captain looked very well and as energetic as usual and the first officer looked well. The first officer, the flight commissioner and cabin crew arrived at the aircraft first. The first officer notified one of the mechanics assisting the aircraft that the total fuel requirement was , all to be stored in tanks on the wings. The mechanic corroborated loading fuel into the main tank. In this case, as required by the technical documentation of the time, the fuel was to be moved to the wing tanks. The mechanic started that job when the captain arrived at the aircraft. Before entering the cockpit, he threw the flight technical record to the floor, showing annoyance, confirming that attitude by later shutting off the fuel transfer faucet between the main tank and the wing tanks, a job that was being performed at that precise moment by the assistant flight mechanic. During their first four minutes on board, the captain, the co-pilot and the commissioner talked about trivial matters in good spirits, focusing on the commissioner's personal issues. When the commissioner left the cockpit, the conversation changed tone and matter as they discussed a controversial situation about their relationship. The captain said, after a reproach from the co-pilot, that he was "going through bad times", to which the copilot replied that he was also having a bad day. Without interrupting the conversation and as part of it, the reading of the Procedures Control List (PCL) for the aircraft started, mixed with the personal issues that worried them and that led them to misread the procedure checklist. This confusing situation, in which the PCL was interspersed with conversation irrelevant to the crew's task, persisted during "push back", engine start and taxiing, up to the moment of take-off, which was delayed by other aircraft waiting ahead of the LAPA flight and heavy arriving traffic. During this final wait, the three men were smoking in