Learn how to use COM and NAV radios in a flight simulator: tune and swap frequencies, select audio and CDI sources, identify stations and fix faults.
In a flight simulator, use COM radios to receive and transmit voice communications, and NAV radios to receive VOR, localiser and ILS signals. Power the avionics, tune the required frequency into standby, swap it active, select the correct audio and navigation source, then verify the station before relying on it.
For Aviation & Real-World Flying practice, treat tuning, listening, transmitting and navigation-source selection as separate actions. A mistake we see constantly is entering the correct frequency but leaving it in standby or displaying GPS guidance instead of the tuned NAV receiver.
What is the difference between COM and NAV radios?
COM radios handle communication, while NAV radios feed radio-navigation guidance to the CDI, HSI or flight instruments.
| Equipment | What it receives | What you must select |
|---|---|---|
| COM1/COM2 | ATIS, ground, tower, approach and other voice services | Active frequency, receiver audio and the microphone/transmit radio |
| NAV1/NAV2 | VOR, localiser and paired ILS glideslope signals | Active frequency and NAV or VLOC as the instrument source |
| ADF | NDB signals | ADF frequency and the appropriate bearing-pointer source |
| GPS/FMS | Satellite or programmed route guidance rather than a NAV-radio signal | GPS or FMS as the navigation source |
COM and NAV controls may share one avionics display, but their frequencies are not interchangeable. An NDB is also tuned through an ADF receiver, not NAV1 or NAV2.
How do I use a COM radio?
To use a COM radio, tune the required service into standby, transfer it to active, select that receiver on the audio panel and make sure the same radio is selected for transmission.
- Power the radio stack. Turn on the battery, avionics master and any required radio or audio-panel controls. Set a usable volume and normal squelch setting.
- Find the correct frequency. Use the simulator's airport information, chart or ATC instructions. ATIS is for listening; ground, tower and approach are used for two-way communication.
- Tune the standby window. Enter the frequency under COM1 or COM2, not the NAV bank. Some older panels tune the active frequency directly.
- Swap it to active. Press the transfer or swap control and confirm that the frequency moved into the active window.
- Select the audio and microphone. Enable the COM1 or COM2 receiver on the audio panel. Select the corresponding microphone or transmitter; listening to COM1 does not always mean you are transmitting through COM1.
- Listen before transmitting. Use push-to-talk, voice recognition or the simulator's ATC menu as applicable. During a hand-off, place the new frequency in standby, read it back, then swap after the controller finishes.
COM1 is normally used for the active ATC conversation, while COM2 can monitor ATIS or another frequency. Monitoring both is useful, but overlapping transmissions can make both channels unintelligible. Microsoft Flight Simulator users can follow our practical guide to built-in ATC, COM tuning and frequency hand-offs.
How do I use a NAV radio?
To use a NAV radio, tune and identify the station, select NAV or VLOC on the flight instrument, then set and interpret the required course.
- Identify the facility and procedure. Determine whether you need a VOR, localiser or ILS. Use the frequency associated with the intended station or approach; tune an NDB through the ADF instead.
- Tune NAV1 or NAV2. Enter the frequency in standby and transfer it to active. Aircraft with older radios may provide only a directly tuned active window.
- Verify the station ident. Listen to the Morse-code identifier through the audio panel or check the decoded ident shown by compatible avionics. Seeing a frequency on the display proves only that it was entered, not that a valid signal is being received.
- Select the correct instrument source. Set the CDI or HSI to NAV or VLOC. If it still says GPS, the magenta route can remain displayed even though NAV1 is tuned correctly.
- Set the course. For a VOR, use the OBS or course selector and interpret the CDI with its TO/FROM indication. For an ILS, set the published front course and use the localiser for lateral guidance.
- Confirm reception and geometry. VOR and ILS signals have limited coverage. Terrain, distance, altitude and approaching an ILS from the wrong side can prevent dependable indications.
Tuning an ILS localiser frequency automatically selects its paired glideslope frequency; pilots do not tune a separate glideslope channel. A DME indication appears only when the facility and aircraft equipment support it.
For detailed radial interception, CDI interpretation and the separate ADF workflow, use our step-by-step VOR and NDB navigation procedure.
Should I use COM1 and NAV1 or the number-two radios?
Use COM1 and NAV1 for the primary task, then use COM2 and NAV2 to monitor or cross-check when the aircraft provides them.
- COM1: primary controller or traffic frequency.
- COM2: ATIS, a pending hand-off frequency or a secondary channel.
- NAV1: primary VOR or approach guidance displayed on the main CDI or HSI.
- NAV2: a crossing radial, backup station or secondary bearing display.
This is a convention rather than a technical requirement. Check which receiver feeds each instrument because some aircraft allow NAV2 to drive the main HSI, while others reserve it for a secondary CDI or bearing pointer.
Why is my COM or NAV radio not working?
Most simulated radio faults come from power, active-versus-standby selection, audio-panel routing, navigation-source selection or being outside the station's coverage.
| Symptom | Likely cause | Fix |
|---|---|---|
| No COM audio | Frequency is in standby, receiver audio is deselected, volume is down or the radio lacks power | Check avionics power, active frequency, COM receiver button, volume and range |
| You can hear ATC but cannot transmit | The microphone selector points to the other COM radio, or push-to-talk is not assigned | Select the intended transmitter and verify the push-to-talk control |
| CDI does not respond | GPS remains selected, the NAV frequency is still in standby or no valid signal is being received | Select NAV/VLOC, swap the frequency active and verify the station ident |
| Localiser appears but glideslope does not | The procedure is localiser-only, the aircraft is outside glideslope coverage or it is approaching unsuitable geometry | Confirm the approach type and intercept it from the published direction and altitude |
| DME remains blank | The station has no associated DME, or the aircraft lacks compatible equipment | Check the facility and aircraft capabilities rather than repeatedly retuning NAV |
| Frequency cannot be entered | It is being entered in the wrong radio bank, or the simulated radio does not support that channel format | Confirm COM versus NAV and use a frequency supported by that avionics unit |
| Chart and simulator disagree | The simulator's navigation database, scenery and procedure data do not match | Reconcile the simulated facility with the procedure data installed for that simulator |
If a VOR remains unavailable in Microsoft Flight Simulator, our VOR signal troubleshooting checks cover receiver selection, avionics power, range and database mismatches.
Do glass cockpits and airliners use the same radio workflow?
The underlying workflow is the same, but glass cockpits and airliners may place tuning, audio and source controls on different panels.
A conventional cockpit usually has dedicated COM and NAV units. Integrated glass avionics combine active and standby frequencies on one display, while an airliner may use radio-management panels and automatic FMS tuning. Automatic tuning does not remove the need to verify the frequency, station ident and displayed navigation source; our explanation of FMS route and radio-navigation functions covers that relationship.
Simulator radio practice builds useful habits, but real-world flying requires the aircraft's approved instructions, valid chart data and appropriate training. Never carry a simulator's stored frequency or procedure into an aircraft without verifying it against authorised information.