Learn how to set up navigation after a cold-and-dark start in a flight simulator, including IRS alignment, FMS entry, route checks and source selection.
After a cold-and-dark start in a flight simulator, power the avionics, align the aircraft’s navigation sensors, set the correct present position, load and check the route, select the departure and arrival, then choose the active navigation source. Do not taxi until the displays, route discontinuities and initial guidance mode are verified.
The correct cold-and-dark navigation setup order
The reliable sequence is electrical power, sensor alignment, position initialisation, route entry, route verification and navigation-source selection. Exact switch labels vary between general aviation aircraft, airliners and add-ons; simplified aircraft may complete several stages automatically.
- Establish stable electrical power. Connect external power or start the APU as appropriate, then power the avionics and required instrument buses. A battery may illuminate some displays without powering every navigation system, and an interruption can restart an alignment.
- Start IRS, INS or AHRS alignment. Set inertial-reference selectors to the position specified by the aircraft checklist. Glass-cockpit GA aircraft normally initialise AHRS and GPS automatically. Keep the aircraft stationary whenever the model requires a stationary alignment.
- Initialise the present position. Where required, copy the displayed GNSS or gate position into the FMS position page. Check latitude and longitude carefully, including north/south and east/west; a large error can produce a displaced map or rejected position.
- Load or enter the flight plan. Enter the origin and destination before adding airways, waypoints and procedures. A route created in the simulator’s planning screen may not automatically reach a third-party aircraft’s FMS, so use our route-building and import workflow if the cockpit and simulator plans disagree.
- Select the departure and arrival. Choose the runway and SID that match the clearance or expected wind. An arrival can be added before departure, but check it again before descent because runway and ATC instructions may change.
- Complete required navigation and performance data. Cruise altitude and aircraft performance entries are commonly needed for VNAV calculations. Lateral route guidance may work without them, but vertical guidance usually will not.
- Activate and inspect the route. Insert or execute any temporary flight plan, then step through every leg on the map and legs page. Look for duplicate fixes, sharp reversals, missing transitions and an incorrect first active leg.
- Select the source and initial guidance. Set GPS/FMS or VLOC/NAV as required, tune any supporting radio aids, and configure the flight directors, initial heading and cleared altitude. Confirm the result on the primary flight display rather than trusting a button light.
Airliner flows differ enough to merit cockpit-specific instructions. We cover the 737 CDU sequence from position initialisation through route checks and the A320 MCDU flow for IRS, INIT and departure data separately.
What changes with each aircraft type?
The required setup depends on which navigation equipment the simulated aircraft actually carries.
| Aircraft type | Navigation setup | Ready-to-taxi check |
|---|---|---|
| Basic GA with VOR/ADF | Power the radios, tune the navaid, set the course and identify the station. | Correct frequency, course, source and usable indication. |
| Glass-cockpit GA or GPS aircraft | Allow GPS and AHRS to initialise, then load and activate the flight plan. | GPS source selected and the correct first leg active. |
| Modern FMS airliner | Align IRS/ADIRS, initialise position, enter the route, procedures and required performance data. | Alignment complete, route inserted or executed, and first leg sensible. |
| Classic INS-equipped aircraft | Align the INS, enter present position and load waypoints manually. | Acceptable alignment status and waypoint sequence verified. |
Can I enter the route while the IRS is aligning?
Usually, yes: most modern airliners allow route and performance entry while inertial alignment continues. Position initialisation is often part of that process, so perform it at the checklist’s specified point and maintain stable power.
The moving map and LNAV may remain unavailable until alignment finishes. If the aircraft moves or loses electrical power, a detailed add-on may require alignment to be restarted; simplified aircraft may align instantly or use an accelerated timer.
Which navigation source should I select?
Select GPS/FMS for flight-plan guidance and VLOC or NAV1 for a manually tuned VOR or localiser. Loading a route does not necessarily change the source automatically.
On Garmin-style equipment, the CDI source annunciation should show GPS for GPS route tracking and VLOC for VOR or ILS guidance. In transport aircraft, LNAV or managed NAV is an autopilot mode rather than a NAV1 receiver selection, so the flight-mode annunciator is the decisive indication.
For an RNAV arrival, keep the route in the FMS/GPS and verify the approach, active leg and minima before arming approach guidance. Our RNAV approach loading and mode checks cover that later phase without duplicating the startup procedure.
Why is the route loaded but not working?
A loaded route will not provide guidance unless it is active, connected to a valid first leg and paired with the correct navigation mode.
- LNAV or NAV will not arm: check that the temporary route was inserted or executed, alignment is complete and an active leg exists ahead of the aircraft.
- The autopilot turns the wrong way: heading mode may still be active, or the FMS may be tracking a previous leg. Confirm the active waypoint before using direct-to.
- The CDI follows a radio instead of the magenta route: change the receiver source from VLOC/NAV to GPS where the aircraft provides that selector.
- A discontinuity remains: inspect it before deleting it. A discontinuity after a vector or manual leg can be intentional; blindly joining the surrounding fixes may create an unrealistic turn.
- The simulator map and cockpit disagree: a complex add-on may use its own flight-plan system. Import or enter the route in the aircraft rather than assuming the simulator plan controls it.
- A SID, STAR or waypoint is missing: the planner and aircraft may use different navigation-data cycles. Select a procedure available in the aircraft and rebuild the affected segment instead of forcing duplicate fixes.
When should I arm LNAV or NAV mode?
Arm lateral navigation only after the route is active, the sensors are aligned and the first leg can be intercepted sensibly. Some aircraft permit LNAV or managed NAV to be armed before take-off; others require the aircraft to become airborne or approach the route.
If the clearance calls for runway heading or radar vectors, use heading mode first and select route guidance when cleared. Always check the flight-mode annunciator: it shows what is armed and active, while the panel button only shows what was requested.