wingman

n. pilot who serves in a subordinate position to the lead pilot; aircraft that serves in a subordinate position to the lead aircraft

A wingman (or wingmate) is a pilot who supports another in a potentially dangerous flying environment. "Wingman" was originally a term referring to the plane flying beside and slightly behind the lead plane in an aircraft formation.The idea behind the Wingman is to add the element of mutual support to aerial combat. A wingman makes the flight both offensively and defensively more capable by increasing fire power, situational awareness (hopefully), attacking an enemy threatening a comrade, and most importantly the ability to employ more dynamic tactics.
See more at Wikipedia.org...

A pilot flying subordinate to and in support of his designated leader; also, the aircraft flown in this role. 1/3/81

Pilote en appui de son chef de formation. Par extension, avion de l'ailier. 1/3/81

Noun
1. the pilot who positions his aircraft outside and behind (on the wing of) the leader of a flying formation
(hypernym) pilot, airplane pilot