Departure for Mar del Plata was delayed by 35 minutes due to bad weather there. The plane finally took off from Buenos Aires at 19:50 for the IFR flight to Mar del Plata. Arriving near Mar del Plata, the flight was cleared for a runway 12 approach and landing. The aircraft arrived over the runway threshold at 85 m and attempted to land. The C-46 overshot without even touching the runway, and a missed approach procedure was carried out. At 1200 m offshore the aircraft descended gradually into the sea. PROBABLE CAUSE: “The pilot failed during a missed approach procedure to observe the instrument flight procedure and attempted to continue visual flight by night in unfavourable weather conditions. The aircraft then lost altitude and descended into the sea. Contributing factors were: 1) As the pilot was not familiar with the airport in this type of operation, he miscalculated during the instrument approach procedure; 2) The pilot’s temporarily confused mental state, when he found himself in this critical situation, affectected his capabilty and skill; 3) The radio beacon was out of service and the lighting was poor because of the weather conditions at the time of the approach; 4) Unsatifactory dispatching of the aircraft by the operator.”