Abstract: In an aircraft which has a tracking system, the aircraft interrogates all target aircraft in the vicinity of the aircraft in order to determine potentially dangerous situations. The interrogation has a predetermined interrogation sequence which includes interrogation pulses and suppression pulses. The target aircraft respond to the interrogation with predetermined parameter information, the target aircraft sometimes responding to the suppression pulses of the interrogation resulting in an indication of false tracks to the monitoring aircraft. A method is implemented which reduces the false tracks resulting from replies to the suppression pulses. The method comprises the steps of forming tracks on responses to the interrogations wherein the responses meet a first set of predetermined criteria. The formed tracks are then identified as suppression pulse tracks or non-suppression pulse tracks in accordance with a second set of predetermined criteria.