Layers and timing is important.
When at very long range in real life the first few puffy acks would be a full click off and almost random. The longer you stayed on course the closer it would get. Stay on one path too long, damage.
At some range this begins to change. The ack is more intense and "first" shots are much closer. At some point, consider proximity rounds the ack is very likely going to damage the plane. This would likely go well below 3,000 feet alt, though you would need to be within 3.0 icon range?
And the timing...beyond icon range, climb to 3,001 feet and instant ack. Those rounds would need to travel at well over 10,000 mph to get there that quick. Not quite actual muzzle velocity, and again first shots are going to be off by a good margin.
Just some realism is all.
Boo