How do you use NDB/DME navigation in a flight simulator?

NDB/DME navigation combines an NDB’s directional bearing with DME slant-range distance. In a flight simulator, tune and identify the NDB on the ADF, select the associated DME through the aircraft’s DME or NAV equipment, then track the published bearing while using DME distances to confirm fixes, descents or turns.

NDB/DME equipment and indications

NDB/DME uses two independent radio aids rather than one combined signal. The non-directional beacon gives bearing through the ADF, while the distance measuring equipment reports distance from its own antenna.

The two antennas may be co-located, but that should never be assumed. Use the chart’s named DME reference because a small separation between the NDB and DME can matter close to a fix. Our guide to interpreting ADF bearings and distinguishing NDB from VOR navigation explains the underlying indications in more detail.

Controls differ across Microsoft Flight Simulator, X-Plane, FSX, Prepar3D and individual aircraft add-ons. Some aircraft tune DME automatically through NAV1 or NAV2; others have a separate DME selector with channel, source and hold functions.

How do you fly an NDB/DME procedure?

To fly an NDB/DME procedure, configure and identify both aids before intercepting the published track, then treat bearing and distance as separate pieces of information.

1. Read the chart before tuning. Note the NDB frequency and identifier, the DME station or channel, inbound and outbound tracks, required altitudes and every DME-defined fix. Check whether the distance is measured from the NDB site or another facility.
2. Tune the ADF. Enter the NDB frequency and select ADF rather than antenna mode. In antenna or ANT mode, many indicators park the needle and provide audio reception only.
3. Select the correct DME source. Tune the chart-listed channel or paired NAV frequency using the method supported by the aircraft. Confirm whether the display is reading NAV1, NAV2 or a standalone DME receiver, and make sure DME hold is not retaining an earlier station.
4. Identify both facilities. Listen to or verify the Morse identifier where the simulator models it. A believable needle or distance is not proof that the correct station has been selected.
5. Interpret the bearing correctly. On an RMI or electronic bearing pointer, the needle head indicates the magnetic bearing to the NDB and the tail indicates the bearing from it. On a fixed-card relative bearing indicator, add relative bearing to magnetic heading and subtract 360 degrees if the result exceeds 360. For example, heading 070 degrees with the needle 20 degrees right gives a bearing to the station of 090 degrees.
6. Intercept and track the published line. Use a sensible intercept angle, usually around 20–45 degrees depending on displacement, then reduce it as the needle approaches the required bearing. Apply a wind correction rather than continually pointing the nose at the beacon.
7. Use DME to identify fixes. At each published distance, carry out the charted altitude, turn or configuration instruction. DME groundspeed and time-to-station are dependable only when flying substantially towards or away from the station.
8. Recognise station passage. When passing close to the facility, the ADF needle swings rapidly towards the rear and DME reaches a minimum before increasing. Do not chase the needle during this unstable period.

How do you track an NDB without homing?

Tracking holds a defined course over the ground, while homing merely keeps the ADF needle pointing at the aircraft’s nose. Homing produces a curved path downwind unless there is no crosswind.

For an inbound track on an RMI, intercept until the needle head reaches the required inbound bearing. Then apply enough crab to keep that bearing steady. If the needle drifts away from the desired bearing, turn towards it to regain the track, then establish a revised wind-correction heading.

For an outbound track, use the needle tail as the bearing from the station. Small corrections followed by time to observe the result work better than large, rapid turns; ADF needles naturally lag and become lively near the beacon.

NDB/DME approaches and DME arcs

On an NDB/DME approach, the ADF normally defines lateral position while DME identifies the final approach fix, step-down points, missed-approach point or turning fixes. The published chart remains controlling because distances, minimum altitudes and missed-approach instructions vary; our complete raw-data NDB approach procedure covers that workflow.

If the chart requires a constant-distance arc, do not treat it as ordinary NDB tracking. Use the DME display to maintain radius and the appropriate bearing source to judge progress, following the step-by-step technique for flying a DME arc.

Automation and GPS substitution

Can an autopilot track an NDB?

Most light-aircraft autopilots cannot track an ADF bearing directly. Their NAV mode normally follows a VOR, localiser, GPS or FMS course rather than an RMI bearing pointer, so use heading mode and adjust the selected heading for wind.

Some older or specialised aircraft can couple the autopilot to ADF guidance, but only use that function when the simulated system explicitly supports it. A mistake we see constantly is selecting NAV mode and expecting the aircraft to follow an NDB needle that is not connected to the autopilot.

Can GPS replace NDB/DME?

GPS can make an NDB route easier to follow, but it does not reproduce raw-data NDB/DME navigation. A GPS waypoint distance may be measured to a different reference point and is not necessarily the DME antenna’s slant range.

Use the ADF and DME when practising the published technique. GPS substitution in real operations depends on approved equipment, the procedure and applicable rules; simulator convenience should not be mistaken for real-world authorisation.

Common NDB/DME failures and fixes

Most apparent NDB/DME failures come from the wrong receiver mode, source or station rather than a broken instrument.

• ADF needle parked near 90 degrees: change from ANT to ADF, then confirm the frequency and identifier.
• NDB received but DME blank: DME is a separate, line-of-sight UHF service. Check the DME channel, NAV1/NAV2 source, aircraft equipment, range and terrain masking.
• Distance looks valid but is wrong: cancel DME hold and verify the displayed station identifier. The receiver may still be interrogating a facility used earlier in the flight.
• DME never reaches zero: this is normal slant-range behaviour. Directly over the antenna, an aircraft 6,000 feet above it will still indicate roughly one nautical mile.
• DME groundspeed is implausible: ignore it while crossing the station’s radials or flying an arc. It is calculated from the rate at which distance changes, not from actual groundspeed over the earth.
• Charted station cannot be received: the simulator’s navigation database or scenery may not match the chart, particularly where a real beacon has been removed or changed. Confirm the simulator’s facility data rather than substituting a similarly named station.
• ADF bearing wanders: bank, station proximity and wind-correction errors can move the indication. More detailed simulators may also reproduce terrain, coastal, night or electrical interference; our explanation of NDB range and reception factors helps separate signal limitations from tuning mistakes.