Patent ID: 7479919

Claim:
A transponder system located on a ground-based unit for alerting surrounding aircraft if the ground-based unit is a threat, the system comprising: a position sensor configured to sense position of the ground-based unit; a memory configured to store predefined threat zone information; a transmitter configured to transmit a predefined transponder signal; and a processor in data communication with the position sensor, the memory, and the transmitter, the processor configured to instruct the transmitter to transmit the transponder signal based on the threat zone information and the sensed position of the ground-based unit, wherein the transponder signal includes at least one of surface vehicle location, ground-based unit speed, direction of travel of the ground-based unit, or a unique identifier of the ground-based unit, wherein the transmitter is instructed to transmit a transponder signal if the processor determines that the speed and direction of travel indicate that the ground-based unit will enter a threat zone within a threshold period of time.