TINKER AIR FORCE BASE, Okla.--Three F-15Cs and an F-15EX assigned to the 85th Test and Evaluation Squadron, Eglin Air Force Base, Florida, refuel with a KC-135 assigned to the 465th Air Refueling Squadron, Tinker AFB, Oklahoma, Oct. 15, 2021. In-air refueling allows fighter aircraft to stay airborne for longer periods of time without having to land to refuel.