Formation flying

User "Flightgear" asked here, if it's possible follow an aircraft in multiplayer mode (over it, with some autopilot function). Because his question was made a year ago and because this thing has intrigued me, I respond here.

Do formation flying with AP (eh, "I want it all, right now and with less effort as possible"). I don't know if it's possible in real flight, in simulated one yes, it's possible, but only if somebody write such autopilot. Maybe just exist and only I don't know about it.

Manual formation flying is difficult (almost to me), but it can be done. You need a lot of trainig, but where you find a friend willing to do training target?

I solved it: I put in multiplayer mode an automatic "sparring partner", Cessna 172P in yellow livery (visibile), flying triangular pattern over Naples bay (all my despect to NIATCA, if you think South sucks, I offer my services right here :P - note for not italian readers: reaction to eternal italian North/South rants, they even founded for italian flightgear community NIATCA "North Italian ATC airports", not "Italian" but "North Italian")

Parameters:
altitude: 2000 ft
velocity: KIAS 95~110
pattern: right turn 120 degrees, straight flight 2 minutes, repeat it ad infinitum.

The "drone" flies in completely calm simulated environment (wind zero) and with fuel consumption frozen. We'll see how many days it lasts there.

It's there, on multiplayer server, available to all. Take off from LIRN Naples/24, fly over bay, find it and follow it for a while. It isn't so easy.

Tecnical background is simple. The drone flyies with AP mode HDG, ALT. Heading bug is regularly modified by telnet connected small Python script.

OK, see you over Naples bay, I go try it just now.

PS. Flight map. The pattern rotates slowly, effect of some precession (or error in script?).

Addenum:
I tried it, not easy even find it, strobe beacons aren't visible at long distance, without mpmap aid I wasn't able to find it. But most difficult thing is flying close to it and don't overfly. Cessna has no air brakes! But it's fun, go try it!

finally I found it, approach it and follow it (for a short time)
Yes, in background there is Vesuvius volcano. 

Addenum 2:
Asked for it in #flightgear, here you are: Python script for triangular pattern
triangular.py. Save it in directory of your choice, run fgfs with --props=5501 parameter (from FGRun Advanced options, Network, Props), take off, fly to selected area, engage autopilot mode HDG ALT. In terminal window switch to script directory and run it with python triangular.py command. For long term flight (as I do), don't forget freeze fuel and set calm weather (wind zero).
For finishing, shut down script with Ctrl+C combination, disengage AP and land as usually.

Addenum 3
I looked at LIRN apt charts, choosen area isn't suitable. There are LIRN/06 STARs and also rwy 24 missed approach route to VOR/DME SOR. So I moved drone over near Salerno bay. It is always approachable from LIRN, but nearest apt is now LIRI Salerno-Pontecagnano. No, I didn't consult LIRI charts yet, maybe it's again wrong position, but who cares in simulated environment? I'll put it in next LIRI NOTAM :)