 The over-pitching on rotation at V1 pitched the aircraft nose up sharply to the point that airflow into the engines was significantly reduced (similar to blowing across the opening of a soda bottle to make it whistle from the drop in pressure) and causing the engines to stall.The plane then pitched back nose-down crashing belly-first into the ground.Also, the aircraft was approximately overloaded, although, given the pallet weighing process, this was believed to be more common than thought beforehand.