According to the report published Publishing by the Indian investigative team , the probable cause was ruled Legal_rulings as the pilots selecting Choosing the `` Open descent/flight idle ” control mode rather than glideslope capture , allowing Preventing_or_letting the aircraft to sink Motion_directional far below the correct flight path .

Investigation Criminal_investigation of the crash revealed Reveal_secret that the faulty auto-throttle reduced Cause_change_of_position_on_a_scale the left engine to idle during climb .

After an initial surface cleanup effort the site sat idle for over a decade .

This caused Causation the autothrottle to decrease Cause_change_of_position_on_a_scale the engine power to idle during approach Arriving .

The subsequent investigation found Coming_to_believe that the flight crew had inadvertently retarded Cause_change_of_position_on_a_scale the power levers below the lowest position allowable in flight ( known as `` flight idle '' ) , causing Causation both propellers to overspeed Motion and leading to Causation a complete loss Earnings_and_losses of engine power .