The aircraft took off from Coca Airport (OCC) at 10:20 hours on a scheduled domestic flight to Pastaza (PTZ). The flight was to take approximately 45 minutes. At 10:52 hours the pilot reported over Arajuno, indicating that he was flying at 4500 ft, mainly IFR. Thereafter the weather conditions further deteriorated and the aircraft finally entered a poor weather zone with continuous rain. It collided with trees and then crashed on a hillside. PROBABLE CAUSE: “The accident was due to adverse weather conditions and imprudence on the part of the pilot who changed from VFR to IFR flight without having the requisite navigation aids for the type of flight he was carrying out. Among the contributing causes were the following : failure to consult the weather report and errors in the airline office, possible overconfidence on the part of the pilot in that he carried out the flight knowing that the radio beacon was inoperative, and presumed negligence on the part of the airport commandant, who failed to declare the aerodrome closed when conditions were below the meteorological minima.”