A "plane" (plain) is a large vehicle designed to transport large (or small) amounts of people over varying distances. There are various types of planes, such as passenger planes, private jets, etc. Think of them as air boats. The air force use planes (not like the one shown to the left) to conduct recon or aerial combat for their country. I myself don't have too much knowledge on planes, as I was in the Deux Marines of The Underground, but there are apparently some that don't know what a plane even is.
