"17 June 1998, General Vorobyov flights on Course training exercises in conjunction with the development of new aviation equipment for R & D Summer research methods perform sophisticated aerobatics figures" with "a special training program for flight crews to perform demonstration flights for the Ka-50 "At the 30 th minute flight at an altitude of about 50 m and a speed of less than 60 km / h in the process of intensive changes in the heel 116 and vibrant with a large reduction in the angle of dive collision happened blade rotor collided with the ground and the pilot, not having the benefit of Salvation, died as established commission investigating the catastrophe, the cause of the accident was piloting the helicopter outside of the Guidelines provided for flight operation restrictions (allowed to fly up to 70 angles of heel, pitch angles up to 60 and the angular velocity on all axes up to 60 deg / s) in the fateful flight of the helicopter nosedive nearly steeply (over 80). In these pitch angles became possible perekommutatsiya of course sovertikali via heel, resulting in a display device to roll CIP-81 has changed at step 180, which can disorient the pilot, which dramatically shifted reflex handle cyclic step This led to an increase in speed reduction to 30 m / s and increase the total angular velocity, which in combination with low forward speed of the helicopter and the right pedal to the emphasis has led to a collision main rotor blades. " (Material from the site airwar.ru)