If you run a VRS (Virtual Radar Server) and want to explore your data a little more deeply, you might end up looking at the main output which is AircraftList.json.
There is a very brief outline for what options you can append to it here; https:/
But it does not tell you how to find your feed ID….
What I ended up doing was using FireFox, turns out it has a JSON formatter built in which presented the data in a human readable JSON object.
Here is how it looked.
So now you can easily expand each of your feeds and drill down through all your feeds and find the exact ID of the one you want.
Once you have the id, append it to AircraftList.json?feed=122 like that for an example.
It will return the aircraft just on that feed rather than your whole VRS install.
Now you can use Node-RED (for example) get msg.payload.totalAc and see how many aircraft are currently being tracked in that feed.