The Curtiss departed Rio Gallegos for an off-airway over water flight directly to Buenos Aires. At 17:00 the crew noticed a drop in no. 1 oil quantity. They were near Comodore Rivadavia Airport at that moment. Investigation revealed that the engine was consuming 1 gallon per 15 minutes of flight (with 23 gallons left). Temperature and pressure were normal, so the crew decided to land a Trelew. The pilot believed that he would spot Trelew before nightfall, but that he would have to make a night landing there. A little later the no. 2 engine oil pressure dropped, combined with a rise in temperature. The engine was stopped and the prop feathered. A descent out of 2700 m was started in order to cool down the no. 1 engine. At 1200 m the crew tried to restart the no. 2 engine, but didn’t succeed. The C-46 kept descending and at 450 m height 1200 kg of cargo were jettisoned. When the altitude became critical, it was decided to ditch the plane near the coast. The plane hit some rocks during while traveling through the water. PROBABLE CAUSE: “Decision to continue a flight with both engines impaired until ditching at night became inevitable, instead of making an emergency daytime landing on any of the various runways in the area at a time when the situation made it clear that this operation was inevitable.”