When you have a vehicle, ship, airplane... that has turrets mounted on it, it's pretty normal that there will be some dead angles where not a single turret can hit there. Some can even have a dead angle as huge as a semisphere. If the enemies are attacking at where your weaponary can't reach, you should move yourself so that they are out of the dead angle, or just get some support fire, isn't it?
But usually, you won't. You just maintain where you are, keep shooting and wasting your ammo or energy (which is very jarring when nothing is at your firing range), while the enemies are still at the vulnerable spots that your weapon can't shoot there. And you do nothing about them. The whole firing doesn't even react to enemies at the safe spot, or outside the effective firing range - if someone is sitting at here, they'll be able to watch the whole firing like firework show for some time.
Of course, static turret mounted on ground won't count - they can't reposition at all, and the ground cannot either.
See also More Dakka
. Compare Spam Attack
, A-Team Firing
. Contrast Point Defenseless
, where you're at the firing range instead of the safe spot, and Hero-Tracking Failure
, where someone actually try to cover the safe spot. Equivalent to a static safe spot in Bullet Hell
. Oh, and if you actually do this, you are Too Dumb to Live
- The spellcard Icicle Fall -Easy- of Cirno in Touhou. It leaves a static safe spot in front of the face, which players can keep shooting here at point blank. She doesn't react to this, however.
- But once you consider the fact that Cirno is an idiot, it's not that surprising.