[′er ¦traf·ik kən′trōl ¦rā‚där ′bē·kən ‚sis·təm] (navigation) A system adopted by the Federal Aviation Agency for use in controlling air traffic over the United States; the aircraft carry identification transponders designed to transmit an airplane identity code, altitude, and additional message when interrogated by an air-traffic controller's equipment. Abbreviated ATCRBS.