2.1 TRENDS IN AEW SYSTEM DEVELOPMENT

The concept of airborne early warning (AEW) is straightforward. AEW is a method that force commanders can use to extend their "eyes" to gain a more complete and extended picture of the theater of battle. The majority of sensors employed by force commanders to assess the overall situation are "line-of-sight" type sensors. This means that the sensors will see in approximately straight lines (with a slight bending due to atmospheric refraction) out to their maximum effective range. The curvature of the earth presents a significant limitation to ground-based, line-of-sight sensors, as shown in Figure 2.1. Also depicted in Figure 2.1 is an AEW platform that extends the available line-of-sight sensor coverage for the detection of threats that would otherwise be masked by the curvature of the earth. Table 1.1 (Chapter 1) includes numerical examples of line-of-sight radar range versus the radar and target heights. The advantages of increased platform height for extending the maximum detection range, especially for low-altitude targets, are evident.

Figure 2.1: Coverage advantage of AEW platforms for low-altitude targets.

This approach to extending the eyes of the force commander has been used effectively by a variety of military forces, using fixed wing, shore-based and carrier-based radar surveillance aircraft and aerostats. The initial mission of these aircraft was specifically airborne early warning; i.e., use of the radar to detect potential threats, and of communications systems to report those threats to the force...