Hopefully you understand I'm not trying to argue with you, just trying to figure out how it works, as I think it's a pretty cool tool. As for the tags, I think you're missing my point. An aircraft flying over a terminal area is still in the enroute structure. Sure, he may be talking w/ a terminal controller, but he's not in the terminal phase of flight. So, that's why you see a bunch of tags flying around cities. What I was referring to was when an aircraft gets picked up for a terminal procedure, like an approach or just a handoff for the visual, they seem to disappear in some form or another. Sometimes the blip stays there, but the tag disappears, sometimes it just goes away all together when on the FAC. I had this running on my machine last night while I was doing something else (because I was curious), and that's what I was seeing.
So even though the tag might disappear, yeah, you're right, the data is still there, which makes sense because they're still in the system. I tried something else...I looked up an airplane that my dad used to own. It had a history of flying once in Sept. It flew from St. Pete to Lakeland, presumably for breakfast, as that's a normal trip (the owners are still friends of the family). But the trip was only logged as 23 minutes. The flight it self usually takes about 30-45 mins, but you usually pick up flight following when east of MacDill AFB, and that gives you about a 20 min flight. Soooo, the point of this riveting story is that it doesn't just seem to be IFR histories....or maybe they had a *****in' tail wind.
Again, I know it doesn't really matter, but it's still kind of interesting to try and figure out.