Complex sentence: The Kerrison Predictor was one of the first fully-automated anti-aircraft "predictors", fire-control systems which would aim a weapon at a plane based on simple inputs like the observed speed and angle to the target.
Split into simpler sentences: The Kerrison Predictor was one of the first fully-automated anti-aircraft fire-control systems. The predictor could aim a gun at an aircraft based on simple inputs like the observed speed and the angle to the target.