HMS Hood 1937 - Air Defence Platform

Here we can see the look out posts for the various crew members of HMS Hood, that were tasked with looking out for enemy aircraft:

Most of these involved some sort of optical sight (such as binoculars), whereby it's operator would locate enemy aircraft, then obtain various measurements (such as bearing and elevation), which in-turn, was fed into several (analogue) fire control computers, which in-turn was relayed to the gun operators (who opened fire). Hood's anti-aircraft guns, were also capable of local control, when (for example) such bridge tower directors had been knocked out.