Radar Systems (Primary, Secondary, ATC, Weather)
Primary radar detects echoes from targets, giving range and bearing but no identity. Secondary radar (SSR) interrogates a transponder, which replies with identity and altitude. Candidates must know the principles of pulse radar, range resolution, and the factors affecting detection (target size, aspect, attenuation). Understand ATC surveillance (primary and secondary), and that SSR Mode A gives identity and Mode C gives altitude; Mode S adds selective addressing.
Weather radar (typically X-band or C-band) detects precipitation by reflectivity; know that it shows precipitation intensity, not turbulence directly, and that attenuation and beam filling affect interpretation. Understand ground mapping and the tilt control.
Traps: assuming primary radar gives identity; confusing Mode A and Mode C; thinking weather radar detects clear-air turbulence; forgetting that radar range is line-of-sight and affected by the horizon. Another trap is the assumption that radar returns are unaffected by target aspect.
Rule of thumb: primary = paint, secondary = identify. If you need altitude, you need Mode C (or Mode S).