Trade Air Flight 729, a Let L-410UVP-E19A, departed Bergamo Airport, Italy, for a night-time cargo flight to Zagreb. The aircraft, in cargo configuration, was used to carry a cargo consisting of small packages for a total weight of 1600 kg. On board, in addition to the two pilots, the commander’s wife was also present as a passenger. The weather conditions were characterized by calm wind and dense fog, which limited visibility to less than 400m. After several requests from the captain, the aircraft was cleared for start-up and taxiing; the aircraft followed the follow-me vehicle from apron 12, where it was stationed, to the runway 28 threshold, as required by Orio al Serio Airport procedures for operations in very low visibility conditions. After take-off, the aircraft was cleared for SID “ORI 5Q”, which provided, for the initial climb, the maintenance of the runway heading up to 2 NM. The aircraft, however, began a slight turn to the left, which, in an increasingly accentuated manner, led it to reverse its flight direction and quickly lose altitude, until it hit the ground with a heading opposite the take-off heading, about one kilometer from the runway, after about one minute of flight. The impact occurred in a ploughed field, after hitting and cutting the cables of a medium voltage power line at the edge of the field. CAUSES: As far as is established, documented and substantiated, the cause of the accident is due to a loss of control in flight of the aircraft. Although the cause of this loss of control could not be established with incontrovertible certainty, it can reasonably be assumed that it was caused by a deterioration in the situation awareness of the crew during the initial climb immediately after take-off. The loss of such situation awareness may have been contributed jointly or severally: – the displacement or incorrect positioning of the load, which would have induced a moment of rotation on the longitudinal axis of the aircraft (roll) not immediately perceived and counteracted by the crew; – spatial disorientation, as a result of the possible optical illusion produced by the high speed “E” TWY lights, which, crossing the thick fog, could have induced the pilot to veer, thus causing the final loss of control of the aircraft. In addition, the limited flight experience of the co-pilot and the inadequate application of CRM techniques by the crew did not allow for a timely identification of the hazardous situation and the necessary actions to recover the aircraft.