Sometimes, what you need is a little bit of buffer. Here's an interesting demonstration as to why:
It's traditional -- and wrong -- in EVE to think of lower-security systems in high-sec as "less safe." A 0.5 system is "less safe" than a 0.9 system, goes this fallacy, because a ganker has "less time" in a 0.9 to gank you before getting destroyed by CONCORD. Increasingly, weapon volleys have become so powerful in New Eden that in point of fact a 1.0 system is no safer than anywhere else. Hell, a low-sec system might be safer than much of high-sec. At least the low-sec systems are less populated, and you enter them prepared to be attacked!
And no volley is more powerful than a Tornado volley when that Tornado is fit with 1400mm Artillery. So here we have a single Tornado firing a single volley and killing a Tengu. That could perhaps be written off as a fluke.
Only we can't, because it isn't. This particular pilot specializes in it. He's killed four Tengus in July (so far), two in June, four in May. All of them were single-handedly volleyed with a Tornado, and most of them were killed in Osmon, a 0.7 system. What's the trick? Well, there isn't one that I can see, other than simple lack of buffer on the part of his victims. All of these Tengus died because they were entirely reliant on active tanking systems that don't engage during the right kind of volley. Warning: scary math follows.
A Tengu fit like this victim's has -- on paper -- about 18000 EHP. But that's all it is, paper EHP. In practice, he has about 4500 shield HP, 3000 armor HP, and 2000 structure HP. The problem is that the shields have only a base 9% resistance to EM damage and the armor has only a base 10% resistance to explosive damage. Without a damage control, the Tengu's structure has no resistances at all. So, if I were going to kill such a Tengu, I'd do it with eight guns split 4-3-1. Split and group the guns in this manner. Load the first (four gun) group with one round each of Republic Fleet EMP. Load the second (three gun) group with one round each of Republic Fleet Fusion. Load the last gun with one round of either of those. Lock your victim, and fire the gun groups in that order.
At the Tengu's resistance to EMP ammo, the first group will strip away its shields and do a small percentage of armor damage, about 300 points or so. The second group will strip away the remaining armor and do a significant percentage of structure damage, about 650 or so. The last gun will do just enough damage to finish the Tengu off. It's a wonderful demonstration of applied algebra. And CONCORD, gate guns, and station guns are entirely irrelevant. This Tornado pilot only gets one volley off, but that's all he needs to kill his prey.
All in all, pretty clever work! I assume that he's shooting Tengus either as they undock from a missioning station (placing himself stationary at the ideal volley range) or as they decloak after jumping into the system (placing himself at zero on the gate). Either way, the Tengu pilots in question clearly aren't activating their hardeners or shield boosters since they don't expect to be attacked by other players. 0.7 systems are completely safe, right? And all in all, this pilot is making himself a tidy profit. Here's a kill that netted about 500 million, enough to fit out three Tornados.
Any amount of buffer would have prevented these losses. Hell, that last Tengu had a Damage Control II in cargo, which probably would have prevented his loss. Active tanks are all well and good but without at least a little buffer, you're vulnerable to being volleyed. And it doesn't matter if you're in a 0.5 system, a 0.7, or a 1.0. You'll die instantly wondering what you did wrong.