Which component is NOT part of the ILS?

The correct answer identifies the "Navigator" as a component that is not part of the Instrument Landing System (ILS). The ILS is a set of ground-based and airborne components designed to ensure safe instrument approach and landing for aircraft. Key components of the ILS include the localizer, which provides horizontal guidance by indicating the aircraft's position relative to the runway centerline, and the glideslope, which offers vertical guidance by indicating the correct descent path toward the runway.

In contrast, a navigator is typically a function performed by the aircraft's avionics and personnel, responsible for guiding the aircraft along its flight path rather than providing specific approach and landing guidance as part of the ILS. The RSDU, or Radio Signal Distribution Unit, is involved in the ILS operation by interconnecting various components and signals to ensure proper functionality as part of the system.

Understanding the roles of these components highlights that the navigator serves a different purpose compared to the precise guidance systems involved in an ILS approach.