Flying formation is a term used to describe the way in which aircraft fly in relation to each other. Two common formations are VEE and ECHELON. VEE is a formation in which aircraft fly in a 'V' shape, with one aircraft leading and the other two following in a triangular pattern. ECHELON is a formation in which aircraft fly in a line, with each aircraft slightly offset from the one in front of it. Both formations are used to increase the efficiency of flight and reduce drag.