height, id, etc.Īgain, Combat Tree was developed to read/trigger the Soviet SRO-2 transponder. But the transmitted data is the same, i.e. Mode 4 is used only to verify friendly status.Īlso have several modes, but those are probably not the direct equivalent to one of the Western modes mentioned above.

Mode 3/A uses codes for air traffic control within the Continental United States (CONUS)/ outside CONUS. Mode 2 provides the personal identification (PI) code for a specific airframe Mode 1 is known as the general identification or mission signal. Military modes 1, 2, and 4 have no civilian equivalent. Mode D has not been established internationally. Mode C is reserved for automatic pressure altitude transmission and has been adopted for both civil and military altitude reporting. Mode B has very limited use and has no military equivalent. Mode A, which is essentially identical to the military mode 3 therefore, this mode is commonly referred to as mode 3/A. Civilian IFF is called SSR (Secondary Surveillance Radar). Combat Tree was escpecially developed to interrogate the SRO-2. Programme startet as 'Seek See' in 1968 after acquisition of some Soviet SRO-2 (Odd Rods) IFF Transponders from Arab MiGs shot down by the Israelis during 1967. APX-80 'Combat Tree' Enemy IFF Interrogator