I'm afraid I have to contradict you here.
From a server operators' point of view, when we're talking about online gameplay the visibility distance for dots and the icon display settings are applied on server side and distributed to all clients in a centralized manner.
If a client decides to change these settings locally, he's much likely receiving a situational awareness benefit over other players and that's plain simply cheating.
From a physiological point of view, you might want to read the study "Predicting Visibility of Aircraft" by Andrew Watson, Cesar V. Ramirez andEllen Salud:
http://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0005594...and "Determination of daytime conspicuity of transport aircraft" by Howell WD (1957) (Indianapolis, Indiana: Civil Aeronautics Administration Technical Development Center. 304 304.)
The bottom line is that unless know precisely what exact direction the other plane is to be expected from, even a plane of the size of a DC-3 can only be detected at a range of 5.5-8.7km.
That'd be your pysioloigically correct dots range for twin engine planes (which gives a good compromise between single engine fighters and heavy 4-engine bombers).
Physiologically and logically in general, the icon range is zero.
In real life planes just don't have any descriptive text or IFF colors around them.
Best regards - Mike