During the takeoff for a charter flight to Palma de Mallorca the no. 4 engine developed problems. The takeoff was aborted and the aircraft returned to the gate. Inspection of the engine revealed damage to the compressor. It was decided to perform a three-engine ferry flight to Zrich for an engine-change. At 22:24 hours the aircraft started its takeoff roll on runway 19. During the takeoff roll, the nose yawed to the right. This was corrected by retarding no. 1 engine power from 85% to 80-60%. The aircraft rotated at 134 knots with 27 degrees flaps. While climbing, the aircraft banked 4-6 degrees to the right and the airspeed suddenly dropped to 10 knots below V2 (145kts). The Convair contacted some treetops, banked 10-15deg and crashed 1800 m from the point of lift-off. PROBABLE CAUSE: During a 3-engine take-off the aircraft entered an uncontrollable attitude with increased drag and decreased indicated airspeed owing to the following combined circumstances: – Unexpected, early loss of external visual references after lift off. During transition from visual to instrument flying the pilot lost directional control, this again resulting in increased drag due to yaw. The presence of a temperature inversion reducing thrust and indicated airspeed. – The presence of wind shear causing further decrease of indicated airspeed, which resulted in large drag increase.