Radio Magnetic Indicator (RMI)

A Radio Magnetic Indicator (RMI) is a navigation instrument that combines the heading indicator with two ADF or VOR bearing pointers, showing the magnetic bearing TO a selected navaid against the aircraft’s current magnetic heading. It provides immediate situational awareness of navaid position without the pilot having to mentally compute relative bearings.

Reading the RMI

The RMI has a rotating compass card driven by the heading indicator — it always shows the current magnetic heading at the top (lubber line). Two needles (typically one single-bar for ADF or VOR #1, one double-bar for VOR #2) point to the magnetic bearing TO each selected station. To fly toward the station, simply turn until the needle is at the top.

RMI and ADF Tracking

The RMI makes NDB tracking much simpler than the raw ADF. With the RMI, to track inbound on a selected bearing: maintain the bearing pointer at the top (pointing to the nose). For wind correction, offset the pointer by the wind correction angle.

Related Terms

See also: ADF, Heading Indicator, VOR.