Which instrument combines a magnetic compass with an ADF or VOR to display magnetic heading?

• A. Automatic direction finder only.
• B. Magnetic compass with GPS display.
• C. An electronic navigation instrument that combines a magnetic compass with an ADF or VOR. The card of the RMI acts as a gyro-stabilized magnetic compass, and shows the magnetic heading the aircraft is flying.
• D. A radio altimeter.

Answer: (C)

This instrument setup is the Radio Magnetic Indicator (RMI): an electronic navigation instrument that blends a magnetic compass with input from a VOR or ADF. The card on the RMI is gyro-stabilized, so it stays steady in the cockpit, and it shows the magnetic heading you’re flying while also displaying the bearing to the active navigation aid (VOR or ADF). In other words, you get both your current magnetic heading and the direction to the nav aid on one display.

Other options don’t provide both features together. An automatic direction finder alone points to the ADF but doesn’t present a gyro-stabilized magnetic heading. A magnetic compass with GPS might show heading but not the integrated bearing to an ADF or VOR. A radio altimeter measures altitude, not heading or nav bearings.