AN/APQ-116 is one of the most numerous terrain-following radars (TFRs) produced in the world, and with over 500 units built, it was a member of a family of TFRs consisted of nearly two dozen models, all of which are based on the same general design principle. First developed by Texas Instruments, and later produced by Raytheon when the latter purchased the radar business of the former. AN/APN-149 This is the first terrain-following radar for use on manned aircraft, designed by Bert Bechtel, a former Navy engineer, who had designed a radar scan template control technique that permitted safe aircraft descent in adverse weather. The concept was the basis of winning a $750,000 US Army contract to develop a radar system to automatically guide a drone aircraft. The US Army did not pursue the project to production, but the US Air Force became interested and believed that Bechtel's innovation would protect the low-flying planes. AN/APN-165 Terrain-following/ground-mapping radar by Texas Instruments for OV-1 Mohawk AN/APQ-89 TFR tested on T-2 Buckeye for pilots to familiarize TFR operation on other combat aircraft. AN/APQ-99 Developed by TI as a multi-modes radar, in addition to terrain avoidance and terrain-following modes, and AN/APQ-99 can also be used for ground mapping. Smaller in size then the Westinghouse AN/APQ-72 and fitted in the nose of for A-7A, RF-4B/C. AN/APQ-99 is also supplied to Germany, Iran and Japan. AN/APQ-101 Terrain-following radar by Texas Instruments. AN/APQ-110 Ku band terrain-following radar by Texas Instruments for General Dynamics F-111A and RF-4C. It replaced the side-looking mapping radar by Goodyear Tire and Rubber Company on RF-4C. AN/APQ-115 Improved AN/APQ-110 terrain-following radar by Texas Instruments for the A-7A, General Dynamics F-111, RF-4C, and C-130E. AN/APQ-115 has a single contoured, spoiled parabola antenna, with a search cone of 5 degrees wide, spanning from +7 degrees above to -18 degrees below to the boresight of the aircraft. AN/APQ-115 suffered from inaccurate references (poor stabilization and Doppler inputs), which directly lead to the development of more advanced system such as AN/APQ-122. The Texas Instruments I-band AN/APQ-116 is a TFR used in A-7 Corsair II and C-130 Hercules aircraft. AN/APQ-116 was basically the integration of previously independent AN/APQ-115 TFR into the ILAAS digital navigation system. The radar also fed a digital weapons computer which made possible accurate delivery of bombs from a greater stand-off distance, greatly improving survivability compared with faster platforms such as the F-4 Phantom II. AN/APQ-122