Barrage & Cover Saves

Can someone explain how this works,

what happens if i hit a unit in a crater for example or a unit in a ruin with no floors ontop of them?

You determine cover from the centre hole of each blast in the barrage. If you are in a crater for example, you are in area terrain, therefore you would be getting a 5+ cover save

even if theres nothing on top of you to stop the blast as it comes from the sky?
is the cover save only given if u go to ground? as this is stupid if get it without going to ground? as a crater would just be a hole??

If you are in area terrain, there is no way the blast fom a barrage can deny you that cover save

thats a stupid rule lol
they should only get cover if they have something ontop of them like a piece of roof etc etc
the internet is confusing some say no cover saves..

just doesnt make sense as if you would put someone in a carter or hole and shoot at it from above with a B52 shell im sure there would be no chance in hell someone would survive lol

The whole 40k world doesn't always make sense. A lascannon can cause a direct hit on a catachan warrior but fails to penetrate his tshirt and muscles because of a roll of 1 to wound.

What's come to my attention though is that ruins is another matter altogether. Wherever the barrage hole is exactly, it would hit the highest floor (e.g. if there is a 3 story ruin with a ground floor and the centre of the barrage has scattered to the first floor. Then that blast counts as hitting that floor, and only models on the same plane can be affected).

Then you would use true line of sight from the centre to determine if the model is partially behind cover or not, just like you would anywhere.

Although if you are in area terrain (e.g. the model is on the base of the ruin, or in a crater), you will still always get your area terrain cover regardless of where the blast may land