Do not like this idea. I think it will only detract from play. Usually I am being pursued by 3-4 civs. Play is challenging enough without allowing them all to be right on top of me.
Besides the programming challenge, I don't think it enhances play. Better solution would be to increase the movement ability of modern units. Distance does matter, remember how long it took the British to get to the Falkan Islands.
Even with NATO, US doesn't always use foreign airports. I don't trust AI's to keep alliances long at all. Remember Firaxis doesnot want civ3 to be an air battle. It is designed to be almost all land battles. Right or wrong this is their vision. Your RFE would flip the game to all air and some ground for mop up.
If we are going to get Firaxis to fix air, let's get the basics fixed first. How would a stealth or F16 land in a city without an airport? Even more, how could they be based out of a city without an airport and run regular sorties?
Another alternative would be to have agreements last 30 to 40 turns, so have time to react. So what if the AI is ready for peace. It is designed to fight 10-15 turn wars. It does not like to run longer wars. Make it suffer WW and don't give peace until you are satisfied it is good for you.
Just because they offer peace does not mean you have to accept. Most of the time I do not agree to peace until I am finished with my counter strike. Yes, I know they want peace when my forces are finally at their border. So, bribe me well or forget it.