Originally posted by Tyro
Your equation assumes the plane flies in a straight line. Whether it works probably depends on the strategy the stealth aircraft is using; if the pilot thinks he hasn't been detected yet and is going slowly without evasive manoeuvers, then firing initially 'dumb' IR missiles in the general vicinity might take it down.
Not at all, it's simply the distance the plane can travel in the amount of time it takes the sound to reach the ground.
When you start figuring in for the heading of the plane, and the available targets, then you can predict the location better.
PS. From what you're describing, the radar on something like an AWACS should have little trouble picking up stealth planes.