The airplane was ferried from the international airport of San Jos‚ to San Jos‚-Tobias Bolanos International Airport to fly tourists to Tortuguero National Park. It arrived at Tobias Bolanos as 12:53. The airplane was prepared quickly for the onward flight. The bags were loaded without weighing them and the passengers were not briefed about the emergency procedures. The flight quickly taxied to runway 09 for departure without permission from the air traffic controller to do so. At 13:04 ATC cleared the flight for takeoff. Because the pilots did not use the check list for departure, they forgot to lower the flaps for take off. The aircraft could not maintain height after takeoff and crashed into a home in San Jose’s Rohrmoser neighborhood, injuring a housekeeper. CAUSA PROBABLE: “Posible p‚rdida de control longitudinal de la aeronave en vuelo, al no alcanzar la velocidad m¡nima de sustentaci¢n, debido a la configuraci¢n de despegue con los flaps del avi¢n en cero, inadecuada para el largo de pista y la distribuci¢n del peso que afect¢ la posici¢n de su centro de gravedad excediendo su l¡mite trasero.” FACTORES CONTRIBUYENTES: 1. La tripulaci¢n no utiliz¢ las listas de chequeo antes de despegar. 2. El sobrepeso de la aeronave en el momento del despegue. 3. La alta altitud de densidad. 4. La falta de supervisi¢n del despacho del vuelo por parte del operador. (Ausencia de procedimientos) 5. La presi¢n autoinducida de la tripulaci¢n para una operaci¢n expedita.