In 1959 the Army started development of the MIM-46 Mauler, which mounted a new high-speed missile on top of the ubiquitous M113 Armored Personnel Carrier chassis, along with a medium-range search radar and a separate tracking and illumination radar. In order to deal with the quick response times needed, the fire control system was semi-automatic; operators would view targets on the search radar and prioritize them, the fire control system would select ones within attack range and automatically slew the missiles toward them and launch. Since the missile would be operating close to the ground in highly cluttered environments, it used a combination of beam riding along the illumination radar and an infrared seeker in the nose, which allowed tracking as long as either the path in front or in rear of the missile remained free of obstructions.