Relative Bearing Indicator (RBI) is also known as the fixed-card ADF. Which of the following options represents this instrument?

• A. Fixed-card ADF
• B. HSI
• C. VOR
• D. DME

Answer: (A)

The main idea is that this instrument shows the bearing to an NDB relative to the airplane’s current nose direction, and its card does not rotate with the aircraft heading. In a fixed-card ADF, the compass card is stationary, and a bearing pointer shows the relative bearing to the station. To determine where the station lies on a map, you combine that relative bearing with your current magnetic heading (read from the heading indicator) by adding them. This is why it’s called a fixed-card ADF—the card stays fixed, unlike floating-card types that rotate with the heading.

So, the Relative Bearing Indicator is the fixed-card ADF. It’s not an HSI, nor VOR, nor DME, which are different navigation indicators and aids.