As X-Plane permits only one plugin to 'acquire' planes at any one time in order to change model or disable AI, etc (XPLMPlanes.XPLMAcquirePlanes), a common problem is where plugins "appear not to work" because one was able to AcquirePlanes, but the others are blocked. Presently, there is no way to tell which plugin has acquired the planes.
I suggest a read-only dataref, or other interface which records the plugin signature, of any plugin which currently holds the planes, perhaps using null if no plugin has it. As a simple alternative, simply Log the acquiring plugin into Log.txt.
Benefit is that plugins can report _why_ they're not working ("Could not acquire because XXX plugin owns the planes.") and/or failure analysis of Log.txt would show which plugin is causing the conflict for the exclusive resource. This should reduce the queries: "I installed the plugin XXX but it doesn't work..."