If the ISD's front arc were within the side arc of the GSD, you could.  In this case, because the arc line for your GSD's side arc falls outside the ISD's front arc, you don't have the shot. An example of your own arc not obstructing LoS, I think, is this: The MC30 has shots into the ISD's front arc from both of the MC30's side arcs (as well as from its front arc).  Both of the MC30's side arcs encompass a piece of the ISD's front arc, and LoS from the MC30's side arc yellow dots