The JU-52 aircraft, HB-HOS, took off from Dbendorf Airfield at 09:03 hours local time together with HB-HOT. The flight took place in beautiful weather to St. Moritz. HB-HOT landed on this runway at 10:22 hours, HB-HOS at 10:24 hours. The crew of the HB-HOS fully extended the flaps on final approach and maintained the prescribed speed of 120 km/h for the given weight until leveling off. The airplane touched down about 50 m after the runway threshold in the middle of the runway and without any perceptible tendency to slide at a speed of 105 – 110 km/h in three-point attitude. The roll-out was initially straight, but the aircraft suddenly drifted slowly to the left. The PIC’s rudder deflection to the right had no effect. He now tried to bring the aircraft back to the center of the runway with the right wheel brake. This also had no effect. The airplane rolled over the left runway edge, whereupon the co-pilot set the left engine to full power. The airplane turned right again, but remained with the left wheel outside the runway. The PIC now ordered power reduction, fearing a ground loop. As soon as the power was reduced on the left engine, the airplane drifted to the left again. Adding power again with the left engine did not help anymore. The airplane now ran with all three wheels into the snow-covered field outside the runway. About 250 m after first leaving the runway, the left landing gear touched the snow bank about 9 m from the edge of the runway. This caused the airplane to turn left about its vertical axis, knocking off the left landing gear and severely damaging the left engine and left wing. CAUSES: The accident was due to a loss of control during taxiing after landing as a result of edge vortices from the same type aircraft that had landed only 2 minutes earlier. Contributing to the accident were: – Snow bank close to the runway edge; – Possibly inappropriate corrective action by the crew.