Fighter Even, An air contact whose identity (friendly, enemy, or neutral) is unknown. Odd. An obsolete deconfliction strategy intended to prevent mid-air collisions. Requires fighters to arrive at the The point in time and space where opposing aircraft meet in an A/A engagement, generally heading in opposite directions. on even, whole thousand altitudes (e.g. 22,000 ft, 30,000 ft, etc.) and the adversaries at odd (e.g. 25,000 ft).