How do I play FlightGear multiplayer?

To play FlightGear multiplayer, enable Multiplayer in the launcher, enter a unique callsign, select a public server, then start at an airport. Friends should use the same server or connected server network and spawn nearby. Allow FlightGear through your firewall; multiplayer traffic uses UDP, which some networks block.

How do I join FlightGear multiplayer?

FlightGear's launcher handles standard public multiplayer and normally requires no separate account. If the simulator is not installed yet, obtain it from our FlightGear download page before configuring multiplayer.

1. Open the launcher. Select your aircraft and starting airport, but do not start the flight yet.
2. Find the multiplayer settings. Enable multiplayer in the launcher's settings or configuration panel. The precise location and wording vary between launcher releases.
3. Enter a callsign. Use a short, unique combination of letters and numbers without personal information. Duplicate callsigns can cause one pilot to disappear or be tracked incorrectly.
4. Select a public server. Choose a nearby server for lower latency. When arranging a flight with friends, using the same listed server removes uncertainty even though public servers are commonly interconnected.
5. Choose the same location. Start at the same airport and agree on a parking stand or nearby landmark. Spawn at parking rather than placing several aircraft on the active runway.
6. Start the flight and check for traffic. Multiplayer contacts may take a short time to appear. The traffic layer described in our guide to FlightGear's map is the quickest way to confirm that nearby pilots are being received.

For scripted or older launch methods, FlightGear also accepts a callsign plus inbound and outbound --multiplay command-line options. The launcher is safer for most pilots because it supplies the available server details without relying on a hard-coded address that may later change.

Which FlightGear multiplayer server should I choose?

Choose a geographically close public server for normal flying, but connect everyone to the same server when diagnosing a problem. A closer server generally reduces latency and visible aircraft movement is less likely to stutter.

Public servers are commonly linked, so pilots connected through different entries may still see one another. Private or disconnected servers form separate sessions, however. Multiplayer traffic is also filtered by geographic distance: two connected pilots on opposite sides of the world should not expect to appear on each other's local traffic display.

Why can't I see other aircraft in FlightGear?

The usual causes are distance, different server networks, blocked UDP traffic or a missing local aircraft model. Check them in that order rather than immediately changing router settings.

1. Confirm the location. Put both aircraft at the same airport and parking area. Similar airport names or different runway ends can place pilots many miles apart.
2. Check the map. If the other callsign appears as traffic but no aircraft is visible outside, the network is working and model matching is the likely problem.
3. Use the same server. Reconnect both clients through the same public server entry. If that works, one pilot was previously using a private, unavailable or unconnected server.
4. Allow UDP traffic. Permit FlightGear through the operating system's firewall. Some workplace, campus, hotel, guest and VPN connections restrict UDP and can prevent multiplayer even while ordinary web access works.
5. Change duplicate callsigns. Every connected pilot should have a distinct callsign.
6. Try another public server. A listed server can be unreachable or overloaded. Select another nearby entry and restart the flight.
7. Compare FlightGear releases. If one installation is much older than the other, test with matching simulator and aircraft releases.

Manual router port forwarding is not normally required for a client joining a public server because FlightGear initiates the UDP traffic. Do not disable the firewall entirely. Port configuration becomes relevant when hosting a private server, using an unusually restrictive NAT setup or running multiple clients that attempt to bind the same local port.

Do friends need the same aircraft and scenery?

Friends do not need identical installations to connect, but matching aircraft and scenery avoids visual discrepancies. Each computer draws multiplayer traffic using its own locally installed files; the server does not send complete aircraft models or scenery packages.

If another pilot uses an aircraft you do not have, FlightGear may show a fallback model or fail to display the intended model correctly. Install the same package by following our add-on aircraft installation instructions, preferably using matching package revisions.

Different scenery does not stop the connection, but mismatched terrain and airport data can make an aircraft appear underground, floating or parked beside a displaced runway. Matching scenery is especially useful for formation flying and ground operations; our FlightGear scenery installation guide covers the correct setup. Time, weather and some aircraft animations can also differ because each client retains local settings and assets.

Does multiplayer include voice, ATC and shared cockpit?

Standard FlightGear multiplayer synchronises aircraft traffic and selected aircraft properties; it does not automatically provide every communication or shared-cockpit feature.

• Human ATC: Controllers can participate in multiplayer, but joining a public server does not guarantee that a controller is present.
• Text and voice: Availability depends on the FlightGear build, radio configuration and session being used. Selecting a multiplayer server alone should not be treated as opening a shared voice channel.
• Shared cockpit: This is aircraft-specific and requires compatible aircraft files and additional coordination. Two pilots selecting the same aircraft on the same server are not automatically placed in one cockpit.
• Physics and collisions: Each client runs its own simulation. Multiplayer primarily shares traffic data rather than providing one authoritative physics session.

On public servers, use a non-personal callsign, begin at a parking position and avoid deliberately obstructing runways or other pilots. If human ATC is active, monitor the agreed frequency and follow its instructions.