A system and method for warning a helicopter of an approaching bullet using existing sensor systems is disclosed. The disclosed method including the steps of: detecting and providing bearing information for detected small arms weapon firing locations near the helicopter, determining a detection area and detection time window for the fired bullet, determining the antennas of the RF transmitting and RF receiving systems covering the bearing of the detected weapon firing; determining a timing sequence and allocating time segments for transmitting and receiving RF signals during the detection time window, commanding the RF emitting system to emit and the RF receiving system to receive RF signals during their allocated time segments, processing RF signals received and determining whether reflected RF signal pulses from the emitted RF signal pulses are present, and outputting a warning where reflected RF signal pulses are detected.