Officer (Setup rallies, a GTLD, since the sniper will most likely be looking through his scope)
Sniper (for engaging enemies before they get to you, especially on maps like Kashan)
Medic (Obvious)
Pilot (can't have a FAC squad without a pilot)
Now this squad isn't PUG friendly, and it would be best to do with clan members and/or people you know well. The pilot could be in another squad, especially if you're all on Mumble, but it's easier if he can see the markers and you've still got BF2 VOIP if for some reason Mumble stops working. A second way of setting your FAC squad would be adding a HAT or LAT kit, or maybe an LMG if this get hairy (but I think one of the squads goals should be remaining hidden), and I think it would be wasting assets that would be getting much more use somewhere else, and you've still got you pilot to call for immediate support if you need it


