"Add 20 Left 30"

[catchv22]

I tried searching for this on Google several times but because I didn't really have a term for this 'position finding(?)' method I didn't come up with much success.

It always sparks my interest when in Saving Private Ryan, Cpt. Miller points out the MG42 nest by saying 'add 20 left 30'. I'm not completely sure how this works and what axis you'd base this 'coordinate system(?)' off of. Anyone have any instructions or links to guides that can help me with this?

Thanks

[Hellfish6]

That's something you'd usually say if you're using mortars. The way it usually works is that you (the observer) tells the mortar fire direction center your position on a map. When you spot a target, you tell the fire direction center how far away it is and which direction. Then the FDC looks at a map, marks your position and then uses the info to figure out where the target is (70 degrees, 1000m, for example).

The FDC runs some calculations and figures out the proper settings for the mortars. The mortars fire on the target and you, the observer, adjust the mortar rounds by telling the FDC to "Add 20, left 30". This tells the FDC to shift their aimpoint 20m up from the initial aiming point and 30m to the left of it.

I don't remember the context that SPR used the phrase - I'm pretty sure it didn't involve mortars, though. I never used a phrase even remotely similar to that when I was a grunt that didn't involve calling for indirect fire. :|

[catchv22]

Yeah, that's why I was confused about it in this situation. He says the phrase but I couldn't tell what coordinates the phrase would be based off of. He didn't exactly mark a position and then go from there. Perhaps he used his own position. Any other thoughts?