While most airplanes get a fresh tank of gas before ever leaving the ground, some get refueled in mid-air. The United States Air Force frequently performs these maneuvers with fighter jets as a part of routine training.
After hours’ worth of planning, a tanker jet gets into position and waits for a fighter jet. The latter approaches approximately 1,000 feet below the tanker before increasing altitude. After the fighter gets into position, a maneuverable boom attempts to connect with the fighter jet’s fuel reservoir to deposit fuel into it.
The boom is designed with multiple safeties in mind; while the controller on the tanker side has full control over when the boom releases from the fighter jet, the boom also contains an automatic release in case of emergencies, such as unplanned turbulence or unexpected weather. Upon disconnecting, the operator can attempt reestablishing a connection.
Once the fighter jet fuels back up, it descends 1,000 feet below the tanker jet, after which can fly away.
The entire mid-air refueling process can be nerve-wracking, but it’s also necessary given the fuel-gulping nature of fighter jets. By refueling in mid-air, fighter jets can avoid time spent landing, refueling, and taking off again.