I'm certainly no Expert, nor i will tend too be one :P
But somehow i get a feeling it shouldn't be too hard too implement at player level eventhough i can understand its quite hard too implement it for the AI..
But isnt there a golden middleway...
I'm mean for a player IFF shoudn't be too hard too implement with all it quirds and oddities of IFF, and in doubt i think like in RL a player can eyeball a target too see if its friend of foe like i think they have too in RL..
But i understand its the AI that causes troubles for implementing it..
Isnt it possible too "cheat" this into the AI (i hate the word cheating)..
Lemme try too explain what i have in my head..
AI has a reference table of Neutral/Friendly/Hostile units, when it notice a target it looks up in the table if its neutral/friend/foe ignores Neutral and Friend..
Within a certain area of operations all non friendly targets are fair game, i doubt a Civ with a Cessna 172 will fly happely around in the middle of a air/ground war without beeing shot by both sides (i doubt in RL in a combat zone where fighting is going on, neutrals and civians arent supposed to be there, and if they do, i recon they are on there own, and smart thing for them is too stay the hell out of sight at least that i would do caught in the middle of a raging battlezone)
In Case its a Friendly with IFF problems, the AI still gets a signal from the damaged plane when its in (certain) visual range, so it knows that its a friendly with no working IFF, cause the plane type is in its friendly reference guide
I know its not a perfect sollution and it nowhere i suppose how it works in reality but i think with some clever programming most traps described here above can be ruled out by this..
Again i'm no expert, but it sounds to me that this would gimmick the working of IFF to a playable model for a AI and maybe you smart programmers can even make this better as i can think of.