There is a design flaw in the aircraft. The engines are so powerful that they, in some instances create a stall condition at a high attack angle. Boeing had to install a device that automatically noses the plane down when this situation is detected. But on takeoff, the plane and pilot is trying to climb out. So when the nose starts dropping, the pilot tries to raise it, causing a control conflict. Unless the pilots know of this feature, they can get confused for the few short seconds it could take to get into a non-recoverable attitude. Something similar happened in the MD-80 where trying to clear an engine surge at low speeds was countered by an automatic throttle increase, which compounded the surge problem. The pilots were not aware of this situation and it led to air disasters.