I joined the Australian Army in '77, so my info is all second hand.

good enough.

snip long distance story

I was going to chime in earlier that ducting caused some really odd experiences
with our friend, the electromagnetic spectrum. Some conditions in the North
Arabian Sea caused our radar to be so reduced in ability that it could not see
more than a thousand yards - but after climbing to a particular altitude, we
found ducting conditions where we were in radio contact with ships hundreds of
miles out. Radio wave propogation is a funny thing..

yfG