Learn how to use GPS in a flight simulator: enter a route, select GPS mode, follow the CDI or autopilot, and fix common tracking problems.
In any flight simulator, use GPS by powering the avionics, entering or loading a route, checking the active leg, selecting GPS/FMS as the navigation source, then following the CDI manually or engaging NAV/LNAV on the autopilot. Always verify waypoint order, altitude constraints and approach mode before relying on guidance.
This general workflow applies to Microsoft Flight Simulator, X-Plane, Prepar3D, FSX and FlightGear, although button names vary by aircraft. You do not tune a GPS frequency as you would a VOR or ILS; the receiver calculates its position and uses a navigation database to identify waypoints and procedures.
How do you set up and follow a GPS route?
- Power the avionics. In a cold-and-dark aircraft, switch on the battery, appropriate electrical buses and avionics master. A blank receiver usually indicates missing electrical power or failed equipment rather than a GPS reception problem.
- Enter or load the flight plan. Add the origin, destination and required waypoints in the intended order. If the simulator's route planner does not transfer correctly into a detailed add-on aircraft, enter the route through that aircraft's own GPS or FMS.
- Inspect every leg. Confirm the active leg, waypoint sequence and any departure, arrival or approach transitions. Remove duplicate fixes and resolve
DISCONTINUITYentries only when the route should genuinely continue between those legs. - Select the GPS navigation source. Use the receiver's CDI control, a PFD softkey or the aircraft's source selector to choose GPS or FMS rather than VOR/LOC. Garmin-style displays commonly show GPS guidance in magenta and VOR/LOC guidance in green, but colours are not universal.
- Intercept the route. Hand-fly to centre the course deviation indicator, or use heading mode to establish an intercept and then arm NAV or LNAV. Our explanation of how autopilot navigation modes capture and track a route covers the aircraft-control side without duplicating GPS programming here.
- Monitor track, not just the map. Compare desired track, actual track and cross-track error. A bearing pointer merely points towards a station or waypoint; it does not necessarily show the active course you should fly.
- Check waypoint sequencing. The active waypoint should advance after crossing each fix. If it does not, look for OBS, SUSP or hold mode, an inactive flight plan, or a procedure leg that requires manual action.
For FlightGear, the controls and data entry differ between panels; our practical FlightGear GPS setup and route-entry walkthrough shows how to power the unit, enter destinations and select GPS guidance.
Which GPS command should you use?
The correct command depends on whether you want an immediate shortcut, a particular route leg or a complete published procedure.
| Command | What it does | Use it when |
|---|---|---|
| Direct-To | Creates an immediate course towards a selected waypoint and may bypass intervening legs. | ATC clears you directly to a fix, or you need simple point-to-point navigation. |
| Activate leg | Makes a chosen flight-plan leg active, normally using its defined inbound course. | You are joining an existing route between two fixes. |
| Load procedure | Adds a departure, arrival or approach without necessarily beginning it. | You want to review the procedure before flying it. |
| Activate approach | Makes the approach sequence available for active guidance. | You have been cleared for the approach and are positioned to join the selected transition or leg. |
| OBS/SUSP | Stops automatic sequencing or permits a selected course, depending on the receiver. | You need to hold a course temporarily; cancel it when normal sequencing should resume. |
A mistake we see constantly is using Direct-To when Activate Leg is required. Direct-To aims from the aircraft's present position at the chosen fix; Activate Leg preserves the route segment and its inbound course.
Why is the autopilot not following the GPS?
Most GPS tracking failures come from the wrong navigation source, an inactive leg or an autopilot mode that has armed but not captured.
- Wrong source: the PFD or CDI still shows VOR/LOC rather than GPS/FMS.
- No active leg: the route is visible on the map, but no waypoint or leg is selected for navigation.
- Heading mode remains active: NAV/LNAV was never armed, or the aircraft has not intercepted the commanded course.
- OBS or SUSP is engaged: automatic waypoint sequencing has stopped.
- A route discontinuity exists: the FMS will not invent a connection between procedure segments.
- The wrong flight plan is displayed: a tablet, simulator map or external panel may show a route that is not loaded into the aircraft's coupled navigator.
- The intercept is unsuitable: the aircraft is too far from the course or flying almost parallel to it, so NAV remains armed. Use heading mode to create a sensible intercept.
Check the flight-mode annunciator rather than assuming that pressing NAV made it active. The annunciator distinguishes a mode waiting to capture from one actually controlling the aircraft.
How do you use GPS for an approach?
Load the correct runway, approach and transition, verify every fix and altitude, then activate or join the procedure only when the aircraft is positioned for it.
For an RNAV approach, keep GPS/FMS selected and confirm that the receiver has entered its approach-guidance mode. The availability of vertical guidance depends on the procedure, navigation database and simulated avionics; a magenta lateral course alone does not authorise or command a descent. The detailed Microsoft Flight Simulator RNAV approach workflow explains procedure loading, fix verification and lateral versus vertical guidance.
An ILS is different. GPS may guide you to the approach, but the final localiser and glideslope normally require the NAV source to change to VOR/LOC and the ILS frequency to be tuned or auto-tuned. Some aircraft switch automatically; others require the pilot to do it.
Does GPS control altitude and descent?
Basic GPS guidance is lateral only; altitude control remains the pilot's responsibility unless the aircraft has a capable VNAV system coupled to the autopilot.
Simple receivers may display a descent advisory without controlling pitch. In that case, use altitude, vertical-speed or flight-level-change mode as appropriate and observe the published restrictions. More advanced FMS installations can calculate and follow a vertical path, but only after the route, performance data and altitude constraints have been entered correctly.