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1-39 As with shipboard radar, airborne radar sets come in many models and types to serve many different purposes. Some of the sets are mounted in blisters (or domes) that form part of the fuselage; others are mounted in the nose of the aircraft. In fighter aircraft, the primary mission of a radar is to aid in the search, interception, and destruction of enemy aircraft. This requires that the radar system have a tracking feature. Airborne radar also has many other purposes. The following are some of the general classifications of airborne radar: search, intercept and missile control, bombing, navigation, and airborne early warning. SUMMARY The following paragraphs summarize the important points of this chapter. RADAR is an electronic system that uses reflected electromagnetic energy to detect the presence and position of objects invisible to the eye. TARGET POSITION is defined in reference to true north, the horizontal plane, and the vertical plane. TRUE BEARING is the angle between true north and the line of sight to the target, measured in a clockwise direction in the horizontal plane. ELEVATION ANGLE is the angle between the horizontal plane and the line of sight, measured in the vertical plane. RANGE is the distance from the radar site to the target measured along the line of sight. The concepts are illustrated in the figure. RANGE to any target can be calculated by measuring the time required for a pulse to travel to a target and return to the radar receiver and by dividing the elapsed time by 12.36 microseconds.