How do I fly a DME arc in a flight simulator?

To fly a DME arc in a flight simulator, tune and identify the charted VOR/DME, approach the published arc distance, lead the intercept turn, and establish a tangent heading. Hold the arc with small heading changes while watching the DME trend, then leave on the published exit or lead radial.

This general technique applies in Microsoft Flight Simulator 2024 and 2020, X-Plane, FSX and Prepar3D, although individual aircraft model their avionics differently. The arc is defined by distance from a specific ground station, not by an approximate circle around the airport. DME supplies distance rather than left-right guidance; our guide to selecting and interpreting the correct DME station explains that distinction in more detail.

What should I set up before intercepting a DME arc?

Identify the arc centre, radius, direction, entry route, altitude restrictions and exit radial before reaching the procedure.

• Brief the charted path: note whether the arc runs clockwise or anticlockwise, where it begins, and whether a lead radial is published for the exit.
• Tune and identify the facility: select the published VOR/DME or VORTAC frequency and confirm its identifier. Do not rely solely on a name shown by the simulator.
• Verify the DME source: make sure the displayed distance belongs to the facility at the centre of the arc. It must not be distance to the airport, an active GPS waypoint or the other NAV receiver.
• Select the correct navigation source: use VLOC or conventional NAV for raw VOR guidance. GPS mode is appropriate only when following a correctly loaded and coded procedure.
• Set the entry radial: use the OBS or course control to select the radial on which the entry occurs, normally with a FROM indication.
• Stabilise the aircraft: reach the required altitude, reduce to a manageable speed and complete major configuration changes before the turn.

If radial sensing, CDI deflection or TO/FROM indications are unfamiliar, review our VOR tuning and CDI guidance for flight simulators before practising the arc.

How do I fly a DME arc manually?

Lead the entry turn, establish a heading tangent to the arc, then use DME trends and successive VOR radials to remain at the required distance.

1. Approach on the published entry route. When approaching from outside the arc, the DME should be decreasing towards the arc value. When departing from inside it, the DME should be increasing.
2. Lead the turn. For a roughly 90-degree entry and a standard-rate turn, a useful starting lead in nautical miles is 0.5 per cent of groundspeed. At 120 knots, that is about 0.6 NM. Entering a 15 DME arc from outside would therefore suggest starting near 15.6 DME; entering from inside suggests about 14.4 DME. Wind, bank angle, aircraft response and entry geometry can require a different lead.
3. Turn towards a tangent heading. In still air, a clockwise arc uses approximately the radial plus 90 degrees; an anticlockwise arc uses the radial minus 90 degrees. On the 090 radial, for example, the clockwise tangent is approximately 180 degrees. The station remains on the right during a clockwise arc and on the left during an anticlockwise arc.
4. Check the rollout distance. Rolling out above the required DME means the aircraft is outside the arc; turn briefly towards the station. Rolling out below it means the aircraft is inside; turn slightly away. Begin easing back towards a tangent before the distance reaches the target so that the correction does not carry through it.
5. Use the twist-and-turn technique. Advance the OBS by 5 or 10 degrees in the direction of the arc. As the CDI centres on that radial, adjust the heading by roughly the same amount and set the next radial. Clockwise radial numbers increase; anticlockwise numbers decrease.
6. Correct for wind. Treat radial plus or minus 90 degrees as a starting heading, not a heading to hold regardless of conditions. Establish the crab needed to stop a persistent DME trend, then make small additional corrections towards or away from the station.

DME controls the radius; the CDI shows radial progress. A constant centred CDI means the aircraft is tracking one straight radial, not following the arc. Small distance variations are normal because the twist-and-turn method flies a succession of short chords rather than a mathematically perfect curve.

How do I fly a DME arc with a G1000?

For a raw-data G1000 arc, display DME from the centre facility, select VLOC, use the HSI course pointer for radial crossings and fly the tangent headings manually or in heading mode.

1. Tune and identify the VOR/DME. Use NAV1 or NAV2 as appropriate and confirm that any selectable DME source is tied to that receiver.
2. Select VLOC for raw data. Use the CDI source control to change from GPS to VLOC, then set the entry or next radial with the CRS control. Look for the correct FROM indication.
3. Confirm the distance label. A field labelled DME should represent radio distance from the tuned facility. DIS or distance associated with the active GPS leg may instead refer to a waypoint and must not be assumed to be the arc DME.
4. Use available cross-checks. A bearing pointer tuned to the centre station should remain roughly abeam on a tangent, but the DME trend remains the primary radius indication.
5. Advance the course in small steps. Set the next radial, turn as it is crossed and monitor the distance throughout. Menu names and the placement of DME information vary between simulated G1000 implementations.

If the procedure has been loaded from the GPS database, inspect the flight plan and map before using it. A correctly coded arc should appear as a curved leg that agrees with the chart. Activating direct-to the centre station does not create an arc; it commands a straight course towards that station.

Can the autopilot fly a DME arc?

Heading mode can fly the sequence of tangent headings, but conventional VOR NAV mode cannot hold a constant DME radius.

VOR NAV mode captures one radial and follows it towards or away from the station. GPS or LNAV may fly the arc automatically only when the loaded procedure includes a supported, correctly coded curved leg. Confirm the active leg, GPS source, lateral-mode annunciation and displayed path; if the magenta route cuts across the arc or reduces it to unsuitable straight segments, use raw data and heading mode instead.

Common DME arc errors and their fixes

Most unstable arcs come from using the wrong distance source, chasing every tenth of a mile or making corrections that are too large.

A mistake we see constantly is reacting immediately to every 0.1 NM change. That creates S-turns around the desired radius. Look for a sustained increase or decrease, make one measured correction, and allow the aircraft time to respond.

When should I leave the DME arc?

Leave the arc at the published lead or exit radial and turn onto the next charted course without descending before the procedure permits it.

Set the exit radial in advance, preferably on a second receiver or course display. If the chart gives a lead radial, begin the turn there. Otherwise, follow the charted termination and the turn anticipation provided by the aircraft or procedure rather than inventing a large unpublished shortcut.

Keep the centre-station DME available until the arc is complete. Retuning the only receiver too early can remove the radial or distance information still needed for the exit. DME hold may help on panels that model it, but only after confirming exactly which station is being held. Our simulator walkthrough for VOR/DME approaches covers charted fixes, altitude restrictions and the transition onto the final approach course.

Why does DME disagree with the simulator map or GPS?

DME measures slant range between the aircraft and ground station, while a GPS or map normally shows distance across the earth's surface to a selected waypoint.

The difference is greatest when high and close to the station. Directly above a station at 6,000 feet above its elevation, DME will indicate about 1 NM rather than zero. On a larger-radius arc the difference is usually much smaller, but the published procedure still expects the specified DME source.

Also confirm that the GPS waypoint, airport marker and radio facility occupy the same coordinates; similarly named features need not be co-located. A large disagreement is more often caused by selecting the wrong station or waypoint than by slant range. Simulator scenery, navigation data and individual aircraft avionics can also model a facility differently.

How should I practise a DME arc in a simulator?

Start with a slow, stable aircraft in calm conditions, hide the moving map and practise one task at a time using only the chart, CDI and DME.

1. Choose a simple entry. Position the aircraft outside the planned radius on an inbound radial, with enough altitude to remain clear of terrain.
2. Fly without wind first. Practise the entry lead and tangent geometry until the DME remains within a small, controlled range.
3. Use 10-degree radial steps. Change to 5-degree steps if the arc is tight or the aircraft is moving quickly.
4. Reverse the direction. Practise both clockwise and anticlockwise arcs so that station-side and radial-number changes become familiar.
5. Add wind last. Introduce a crosswind and learn to recognise a trend before correcting it. Use the simulator map afterwards to review the ground track rather than relying on it while flying.