The MCAS senses the amount of lift on the plane's nose, and automatically adjusts the plane's attitude to bring the nose back down and avoid the stall. With the Lion Air accident, investigators found that the pilots were not trained about this system, so that when it engaged, they had fought against the MCAS' control, likely leading to the crash. There was also evidence that the MCAS had faulty sensor data regarding the plane's angle of attack, that caused the system to engage too early while the plane was in a climb, giving the pilots little chance to deactivate it and regain control of the aircraft.[1] While the cause of the Ethiopian Air flight has not yet been determined, the preliminary investigation shows the plane's behavior prior to crash similar to the Lion Air accident.[2]