AN / APQ - 116 AN / APQ - 116 is one of the most numerous terrain - following radar s ( 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 Mr . Bart 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 . < ref name = " AN / APN - 149 & AN / APQ - 99 " > < / ref > 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 and RF - 101 . AN / APQ - 99 is also supplied to Germany , Iran and Japan . AN / APQ - 101 . Terrain - following radar by Texas Instruments . AN / APQ - 110 . K band terrain - following radar by Texas Instruments for General Dynamics F - 111 A and RF4 - C . 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 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 . X band multi - mode radar by Texas Instruments for C - 130 Hercules , Boeing RC - 135 , Boeing T - 43 and Boeing E - 4 . AN / APQ - 122 has a slotted planar array antenna with a separate X - band receiver used to generate MRI video , with a search cone of 7 . 5 degrees wide , spanning from + 8 degrees above to - 17 degrees below to the boresight of the aircraft . For AN / APQ - 122 ( V ) B , the stabilization reference could either be manually or automatically switched to MD - 1 gyro if the LN - 15J inertial navigational system become unreliable or inoperable , thus terrain following operation can still continue , where in earlier system such as AN / APQ - 115 , if the Doppler fails , the terrain following operation would be discontinued . AN / APQ - 126 . 60 kW improved AN / APQ - 116 J band terrain - following radar by Texas Instruments for A - 7D / E AC - 130 and CH - 53 Sea Stallion . This is primarily AN / APQ - 116 / 122 incorporating improved maritime capability . Specifications : AN / APQ - 134 . K band terrain - following radar by Texas Instruments to replace AN / APQ - 110 for F - 111A / FB - 111A . AN / APQ - 139 . K band multi - mode radar by Texas Instruments for B - 57G specially designed for night interdiction missions in Vietnam . AN / APQ - 146 . Improved AN / APQ - 134 K band terrain - following radar by Texas Instruments for F - 111C / F . AN / APQ - 147 . TFR for initial batch of MH - 60K AN / APQ - 154 . Improved AN / APQ - 141 terrain - following radar by Texas Instruments for HH - 53 . AN / APQ - 158 . Improvement of AN / APQ - 126 with 15 line replaceable units for the MH - 53 Pave Low helicopter and PAVE LOW III requirement . Designed to perform terrain following mode / function in high clutter area such as in cities . AN / APQ - 162 . Development of AN / APQ - 99 for RF - 4C , incorporating experience gained from AN / APQ - 116 and other radars in the family . AN / APQ - 168 . multi - mode radar by Texas Instruments for HH - 60D & MH - 60K . Increased jamming resistance , improved weather penetration , better guidance in turn flight , and better power management function in semi - covert mission . The radar can operate in terrain - clearance , terrain - avoidance , air - to - air ranging and cross - scan modes , the latter combining ground - mapping or terrain - avoidance with terrain - following . A terrain storage facility permits the radar to have a reduced duty cycle , thereby reducing the probability of detection by enemy ESM equipment . There ' s also the incorporation of built - in test ( BITE ) provides a high degree of fault isolation and detection . AN / APQ - 171 . Improved AN / APG - 146 terrain - following radar by Texas Instruments for F - 111C / F , developed by Texas Instruments in the mid - eighties with the objective of replacing the four different TFR models used across the USAF F - 111 fleet with a single type . While the old TFR had an MTBF around 20 hours , MBTF for the AN / APQ - 171 is better than 50 hrs . AN / APQ - 172 . Improved AN / APQ - 162 TFR for RF - 4C . AN / APQ - 174 . for the MH - 60K and MH - 47E helicopters AN / APQ - 186 . Improved AN / APQ - 174 by Raytheon for CV - 22 AN / APN - 237 . K band terrain - following radar by Texas Instruments part of AN / AAQ - 13