Icon can't really change size...
Too much going on if the enemy plane is within 1k of you there's really no point to the icon doing anything.... maybe even lose the icon altogether(under 1k).... range is pretty easily determined under 1k at least roughly.
Plane type should perhaps be abit further than 2k as well, thats about 1 1/4 miles... make it 3 or 4k for an id
SKurj