I saw many times green dot dissapeared when dived at enemy field and reappeared again as he zoomed away. So I dont think Im wrong at it.
Then that is a 'bug' or display issue. Certainly not something that can be maintained for a controlled period of time.
The OP brought up something that has been on my wishlist for years.. and has been discussed many times. The desire to conduct a mission without being monitored by fellow countrymen.
There are some people that take a perverted pleasure in contacting opposing countries that such 'sneak' missions are enroute. Whether it's because they are personally opposed to that style of play, or if they just want to screw the people involved.. it's still a mean and dastardly thing to do.
Bases will flash when an opposing force is approaching, giving ample time for defenders to launch and thwart such attacks.. as a matter of fact, that's one of the things I like to do, at times. Watch for a flahing base with no enemy dar bar present, then go goon hunting.
Conversely, I've also been the goon that's hunted in such cases.
It's just another angle of gameplay for those that like those sorts of things. No different from furballing, GVing, Strat bombing, .. etc.