Like all secondary radars, the INKAN emits a microwave pulse that “interrogates” a transponder which all airplanes of a certain size are required to carry on board by international law. The passive echo of the pulse tells the system the direction and azimuth of the plane, while the transponder on board informs its identification and altitude.

Secondary radars have substantially increased the safety of airport procedures, but are unable to detect “non collaborative transits” lacking a transponder. Thus, they team up with primary radars, and may transmit their data to or from remote control centers. They cover a range of 200 nautical miles (380 km) and 360 degrees around, and detect planes flying as high as 100.000 feet, within 0.5 and 45 degrees of elevation. In heavy air traffic, INKAN can detect up to 400 flights at one time, or up to 200 of them in a 90 degree horizontal scan.