What does the Airbus A320 DDRMI do in a simulator?

The Airbus A320 DDRMI—Digital Distance and Radio Magnetic Indicator—is a backup raw-data navigation instrument. It shows aircraft heading, bearings to two selected VOR or NDB stations, and DME slant-range distances. In a flight simulator, use it to cross-check the navigation display, locate radio aids and practise conventional radio navigation.

For Aviation & Real-World Flying, the key distinction is that the DDRMI presents radio-receiver data rather than a computed flight-plan route. It uses the A320’s heading reference and navigation receivers; it is not a miniature moving map. Our guide to locating the A320’s cockpit controls and displays provides wider panel context.

What does the Airbus A320 DDRMI display?

The standard DDRMI combines a rotating heading card, two bearing pointers and two digital DME readouts.

The pointer head gives the bearing to the station in the same reference as the compass card. For example, with a heading of 090 degrees and the pointer head on 120 degrees, the station is 30 degrees to the right. The pointer tail gives the reciprocal bearing from the station.

The instrument does not show VOR course deviation, glideslope information or a flight-plan track. Selecting ADF also does not create a distance reading: an NDB provides bearing information, while DME comes from separate DME equipment, commonly paired with a VOR.

How do you use the DDRMI in a flight simulator?

Tune a valid radio aid, select the matching receiver on the DDRMI and then read the pointer against the compass card.

1. Power and align the avionics. The radio receivers require electrical power, while the compass card needs valid heading information. A cold-and-dark A320 may not show useful DDRMI indications until its systems are ready.
2. Tune the station. Enter the VOR or ADF frequency through the simulated FMGC/MCDU radio-navigation page, or let the FMGC autotune it where supported. Our explanation of configuring radio-navigation data through the A320 MCDU covers that part of the workflow.
3. Select the receiver. Set pointer 1 to VOR 1 or ADF 1 and pointer 2 to VOR 2 or ADF 2 as required. The single- and double-bar shapes let you distinguish them at a glance.
4. Confirm the station. Check the decoded identifier or audio ident where the aircraft add-on models it. Never assume a moving needle proves that the intended station has been received.
5. Read bearing and distance. Compare the pointer head with the heading card and use the DME window only when the tuned facility provides DME. Remember that DME is direct slant range, not horizontal or along-track distance.
6. Apply a heading correction. To approach a station, turn towards the pointer head, then correct for wind rather than continually chasing the needle. For a radial intercept or hold, use the bearing and its reciprocal to choose an intercept heading.

Near station passage, the pointer may swing rapidly through roughly 180 degrees. That is normal. DME may also reach a minimum greater than zero because an aircraft several thousand feet above the transmitter still has measurable slant range.

When is the DDRMI useful?

The DDRMI is most valuable as a persistent raw-data cross-check when the main navigation display is busy, configured differently or unavailable.

• VOR or NDB tracking: Monitor whether the bearing is moving towards or away from the desired value.
• Position checking: Combine a station bearing with DME, or use reciprocal bearings from two stations, to confirm the aircraft’s approximate position.
• Station passage: Watch for the rapid pointer reversal and minimum DME.
• Navigation-display verification: Compare the DDRMI pointers and distances with the VOR/ADF information shown on the ND.
• Failure practice: Continue limited radio navigation after losing an ND, provided the heading source and relevant radio receivers still work.

Calling it a backup instrument does not mean it is completely independent. A failed heading source, unpowered receiver or unavailable radio aid can remove the DDRMI information as well.

Can the A320 autopilot follow the DDRMI?

No—the DDRMI is an indicator and does not command the autopilot by itself.

You can use its bearing information to choose headings while flying manually or in selected heading mode, but the autopilot follows the active guidance mode shown on the flight-mode annunciator. Managed NAV, LOC and approach guidance come from their respective systems, not from the DDRMI pointer. See our guide to cross-checking A320 autopilot modes and navigation indications for that distinction.

Why is the DDRMI blank, flagged or showing the wrong station?

A missing or unexpected indication usually comes from power, tuning, reception or incomplete simulator modelling rather than a fault in the flying technique.

• No compass-card movement: Check electrical power and ADIRS alignment or heading validity.
• One pointer is parked or flagged: Verify its VOR/ADF selector, receiver number, frequency, station range and identifier.
• DME shows dashes: The station may not provide DME, the signal may be out of range, or that DME function may not be modelled. An ADF-selected NDB does not supply distance by itself.
• The DDRMI disagrees with the ND: Make sure both displays are using the same receiver. One may be showing VOR 1 while the other is showing VOR 2, or the FMGC may have autotuned a different aid.
• The gauge never responds: A320 cockpit standards and simulator add-ons differ. Some reproduce the physical DDRMI fully, while others simplify it, omit it or leave parts of it decorative.

A common mistake is reading the pointer’s clock position as a heading. The needle shows where the station lies relative to the rotating heading card; the number beneath its head is the bearing to the station.