The A-10 Thunderbolt II, nicknamed the Warthog, is the United States Air Force’s primary low-altitude close-air-support aircraft. It is the only Air Force aircraft produced specifically to support ground forces. It does this using the 30-millimeter Avenger Gatling gun mounted in its nose to clear the battlefield and create a safe path for US ground forces. Soldiers named it the Warthog because of its "ugly" appearance and the guttural sound created by the Avenger. The A-10 has been at the center of a debate within the US Armed Forces about whether or not the nearly 50-year-old aircraft should be retired in favor of the more modern F-35 Fighter Jet. Insider visited Davis-Monthan Air Force Base in Tucson, Arizona, to see how pilots are trained to fly the Warthog.