I'm bored and I thought I'd write up a pseudo-code description of how the 88mm ack should work:
Calculate distance from ack to target: D
Calculate Time of projectile flight: T = D / Speed of projectile.
Calculate Position plane will be at in T Secs: Ppoint = (pX + dX*t, pY + dY*t, pZ + dZ *t)
Calculate Aim Point:
If new target: Apoint = Ppoint + large random number.
If already 'locked' on, Apoint will chase Ppoint with some sort of homing algorhythm
When it fires, it spawns a blast at Apoint that goes off T seconds later.
If the plane is far away but traveling straight it will be dead meat quickly. But if it turns just a few degrees, Ppoint moves by
quite a large amount. e.g. when t = 10 seconds and speed = 300 kts (or ~150Yps) a 10 degree turn means the pPoint shifts by about 250 yards.
Hard to home in on something that can jump 250 yrds in the time it takes to turn 10 degrees!
And if the homing algorhythm keeps averaging between two points (one low and in front of, one high and behind) coverging on the predicted location of the plane it can simulate spotting pretty well. As an added bonus, if the plane jinks too much, the convergence algorhythm would have to start over with a fresh point to converge from. This simulates spotters getting confused by a well flown plane and having widen the area of their ack.
Just a thought. If you want I can write up the c code to do it

~Lemur