A method and system for reducing the risk of a moving machine colliding with an object involves a receiving antenna attached to the machine receiving an RF signal transmitted by a transmitting antenna attached to the object and energized by a power source. A processor operatively connected to the receiving antenna carries out a computer-implemented process under the direction of a set of program instructions stored in the memory component to determine the machine-object distance based on the strength of the RF signal at the receiving antenna. If the machine-object distance is less than a specified minimum safe distance, then the processor takes a preventative action such as actuating a sensory alarm, actuating a means for slowing the machine, or actuating an acoustic location device to more accurately determine the machine-object distance. The processor may also take a preventative action based on a state variable encoded in the RF signal.