I'll give you a perfect example of this and why I agree that the notification of "base under attack" should at least have its range shortened if the attackers aren't showing up on dar.
Last night, I'm stooging around in an La-7 near A18, after finishing off a B-17, when I see a very low dot far in the distance. I check radar--nothing, no dot, no counters in the sector. BUT, at that point, squeakin' Betty gives out with "base under attack!" and A18 starts flashing.
So I check it out. After 2-3 minutes of lowering down from 17k, I see three more dots. I check dar again--no dot, no counters in the sector, and now I'm confused. Maybe it's a train? A resupply convoy or something? Can't be a bad guy ten miles south of the base, I figured A18 was under attack from the north...but, can't ignore that warning.
Finally, one of the dots turns into a 109! The other three turn out to be two B-26s and a P-51, either at weed-clipping height, or maybe even
parked in the grass, I don't know. To make a long story short, the 109 gets me (because, well, I
really suck coming off a long layoff, and I was never that good before) and the buff group and attached C-47 wind up coming extremely close to sneaking A17.
If it hadn't been for that base alert, I would have written that dot off as a friendly and not bothered checking it out. And they were a good ten miles southwest of A18 when I stumbled over them.
guys, very audacious raid.