The F-111 Aardvark is a two seat medium to long range fighter-bomber developed and built by General Dynamics, with assistance from Grumman. One of its primary roles was to penetrate heavily defended airspace at low altitudes and high speeds, enabling the aircraft to remain undetected by radar and unstoppable in speed, while on route to drop ordinance on a target. The terrain-following radar system on board aided the pilot in maintaining a relatively constant altitude over the ground.