In game #554659 the Bristol I was tailing appears to have fired through a Snipe directly between my plane and the Bristol. Is this legal because the hex directly behind the Bristol is a no fire hex? This is an odd quirk that I do not remember encountering.

Thanks for any and all clarifications.

Line of fire: the observer can always fire at all the planes without checking for planes hiding other planes. The only exception is when there is no deflection between to two planes and another planes stays exactly in the middle. This can only happens when the enemy plane is exactly behind to plane with the observer and there is no deflection.