I collectively refer to "Multiplayer Clients" in case of plugins using the multiplayer feature and dataRefs, which X-Plane offers as a standard way of displaying additional aircraft beyond the user's plane. Popular examples are XSquawkBox, X-IvAp, Swift, World Traffic, PilotEdge...and certainly LiveTraffic itself. Last but not least, X-Plane's native "AI Aircraft" are the original. All of them draw planes into the sky.

This page

• provides some background on multiplayer / AI planes​

• explains the Highlander issue: There can only be one plugin ton control AI planes

• ​summarizes all features that help you running LiveTraffic in parallel to other multiplayer clients

Background: What are Multiplayer / AI Planes?

The multiplayer feature, now often referred to as "AI Aircraft", was originally intended to render up to 19 additional planes so to that the simulation pilot wouldn't feel alone. X-Plane's "AI Aircraft" in the Flight Configuration are exactly that. Any plugin, however, can take over control and set the AI planes' positions, and that's what multiplayer clients usually do. If no plugin takes over, then X-Plane itself creates aircraft on artifical routes (which might be resource intensive!).

On the other side, many plugins read the positions of the AI Aircraft to work with them. Most obviously and always available, X-Plane's internal map displays the planes' positions. External map tools like Little NavMap or FSTramp do so as well. TCAS display implementations also use AI planes' positions to compute conflicting traffic. X-Plane's standard plane "Cirrus Vision SF50" features a good implementation (which I often use for testing), as do many add-on planes. And camera tools like ABC work on them, too...and so on.

See here for a screenshots of a collection of tools.

In the Flight Configuration you configure how many AI Aircraft X-Plane is to support (up to 19) and specify an aircraft type, which is mainly of importance if X-Plane flies these aircraft. The more you configure the longer takes your X-Plane startup.

But some reading plugins take the number of configure AI planes into account. Little NavMap, as an example, only displays as many AI Aircraft in the map as are configured in X-Plane, as does X-Plane's internal map. They require you to set up AI aircraft. Other tools, like FSTramp or some TCAS implementations, don't care and try to read all 19 possible planes. (See list of tools.) So to be on the safe side you'd better configure 19 AI Aircraft.

Most multiplayer clients, LiveTraffic included, don't actually use the configured AI planes for rendering planes in the 3D world, but only make use of the standardized and well established way of informing others about additional planes. LiveTraffic can and will always display planes in the sky, no matter if it is in control of AI Aircraft or not.

As you can see, a couple of parameters play a role. Here is a quick rundown what you may expect in different configurations:

The Highlander Issue: There Can Be Only One

...plugin to control AI Aircraft. This is an X-Plane design limitation.

This means that only one plugin can control what plugins and tools read about multiplayer planes. For example, only one plugin controls what will appear on your TCAS display. If another client, say X-IvAp for the sake of example, controls AI aircraft and then LiveTraffic tries to get control (during startup or via the "TCAS Controlled" menu item) LiveTraffic cannot and the following is seen on screen and in the Log.txt file:

Log.txt (Extract)
WARNING: LiveTraffic did not acquire multiplayer planes!!
    Without multiplayer plane control, we cannot fake TCAS or render ACF aircraft!
    Make sure you remove any plugins that control multiplayer aircraft if you want these features to work
LiveTraffic 1562510561.1 WARN  src\LTMain.cpp:527/LTMainTryGetAIAircraft: LiveTraffic does not control AI planes and can therefore not create TCAS blibs!

This can be disappointing if you have LiveTraffic and X-IvAp running, both render planes, the sky is full...but your TCAS only shows the X-IvAp traffic. But that's the way it is. We cannot change this in principle.

Another design limitation of the multiplayer interface is that it only transfers numerical information on aspects like position, heading, attitude and some control surface positions. It doesn't even transport speed information. (Reading plugins can compute it only from delta position information.) And there are no text transfer mechanisms for, say, aircraft type, tail number, call sign etc.

Features Supporting Parallel Usage

Menu command "TCAS Controlled"

With the menu command "TCAS Controlled" (which you could assign to a keyboard shortcut or joystick button) you specify if LiveTraffic is in control of AI Aircraft.

This is a toggle: You can switch it on or off. If it is on then LiveTraffic controls AI Aircraft and hence the blibs on your TCAS display and on map tools. If it is off then you can have another client control AI Aircraft. (How this is done is up to the other client...)

Basic Setting "AI/TCAS on request only"

By default, LiveTraffic tries to get in control of AI Aircraft at startup. If you prefer another client to have control after startup then you may want to activate the option AI/TCAS on request only in the Basic Settings. If set, LiveTraffic will not ask for AI control during startup. You can still use the menu command "TCAS Controlled" to switch control in case you want to.

Limit Display of Aircraft On or Near the Ground

Given LiveTraffic's limitations especially in the area of taxiing and gate movement some people might prefer other plugins for creation of airport traffic while LiveTraffic is pretty good at high altitudes.

There are 2 options in the Basic Settings, right-hand side, which allow you to

• hide all aircraft below a certain height above ground, or

• just hide taxiing aircraft (while still seeing aircraft as soon as they switch to Take Off Roll and as long as they are rolling out after touch down).

Other airport traffic generators can then fill the void without interfering with LiveTraffic's planes.

Making CSL Packages Unique to LiveTraffic

When running LiveTraffic in parallel with other multiplayer clients you will suffer from the "Missing Gear" issue: Some planes, often the planes controlled by the other client, will never show gear, flaps, or lights.

LiveTraffic offers a workaround for advanced users. The Python script CSL2XSB can convert CSL package to only work with LiveTraffic. When then also deactivating the CSL Setting Register original libxplane CSL dataRefs LiveTraffic no longer conflicts with other multiplayer clients. The details are described here.

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