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.
According to the U.S. Air Force,
The traditional military definition of a “Wingman” refers to the pattern in which fighter jets fly. There is always a lead aircraft and another which flies off the right wing of and behind the lead. This second pilot is called the “Wingman” because he or she primarily protects the lead by “watching his back.”
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, attacking an enemy threatening a comrade, and most importantly the ability to employ more dynamic tactics.
The USAF extends the wingman concept to include wingman culture. Wingman culture generalizes the concept of a wingman to include airmen helping airmen. The wingman culture concept has great potential for verbification, for example, that airman should be wingmanned.