A monitoring system includes a sensor that may output a sensed moving speed of a vehicle system. The monitoring system may also include one or more processors in communication with the sensor. The one or more processors may calculate a predicted speed of the vehicle system based on one or more forces acting on the vehicle system, and compare the predicted speed with the sensed moving speed. The one or more processors may also control movement of the vehicle system based on comparing the predicted speed with the sensed moving speed.