The DC-6, which had recently been delivered to KLM, was being used for a training flight at Schiphol Airport. Several takeoffs and landings were uneventful. Next the captain would demonstrate a takeoff with simulated engine failure. The aircraft was positioned on runway 23 and takeoff power was applied. At a speed of 137 km/h the captain began pulling the control column and the nose gear lifted off the runway. At a speed of 169 km/h the no. 1 engine power lever was retarded. The airplane had not left the ground yet and started drifting to the left. Full rudder was applied to counter the drift. The right hand main gear then also lifted off the runway. With the left hand main gear still on the runway, the airplane ran off the side of the runway and became airborne. With some obstacles ahead, full power was added on engine no. 1 but the engine oversped. The left wing then struck an earthen wall. The DC-6 swung and struck a ditch. PROBABLE CAUSE: “Ten eerste kan het ongeval zijn veroorzaakt door een storing in het keerstandsysteem van de schroef van motor 1, waardoor de bladhoek van deze schroef niet correct gesteld werd. De tweede mogelijkheid is, dat gezagvoerder […] te laat het naar links weglopen van het vliegtuig heeft gecorrigeerd met tegenroer. Tussen het begin van de slip en het tegenroer lag ca. 3,5 seconde. Bij het terugnemen van gas op motor 1 moet, zo stelt men vast, onmiddellijk tegenroer worden gegeven.”