incoming (n.)

late 14c., "action of coming in," from incoming (adj.), which is attested from 1753. As "that which is coming in" from 1892, originally of game; transferred in World War I to artillery; as a warning cry of incoming shellfire, it seems to date to the U.S. war in Vietnam (1968).

1753, "coming in as an occupant," present-participle adjective from in (adv.) + come (v.). Of game, from 1892; transferred in World War I to artillery; as a warning cry of incoming shellfire, it seems to date to the U.S. war in Vietnam (1968).