The only complete wing in Southeast Asia flying the EC-121 Super Constellation, the 553rd Reconnaissance Wing was formed 1967 and based at Korat, Thailand. All 30 EC-121Rs (converted from ex Navy EC-121K/EC-121P aircraft) were delivered to the wing during the course of 1967.
67-21485 seen on duty during 1968, Zoggavia Collection.
The EC-121R differed from Air Defense Command’s airborne warning and control version of the EC-121 in that the radomes had been removed and special electronics and antennas had been installed. The 553rd RW - its call sign was "Batcat", used overland and off the coast of Vietnam,
over Laos and Cambodia, monitoring and retransmitting the low-power
sensor signals - flew its first operational mission on Nov. 25, 1967.
The EC-121R carried a crew of 17 or 18, including a combat information center crew of six or seven working the Igloo White gear in the back of the aircraft. It was a long duty day. To provide round-the-clock coverage of the sensors, the Batcats orbited the Ho Chi Minh Trail in eight-hour shifts. With transit times, the flights lasted about 10 hours. Briefing and debriefing made the missions still longer. The 121s sent a live feed of the sensor alarm data to the computers at Task Force Alpha. (Airmen working the scopes at NKP could not listen directly to the sensor microphones, but the mission crews on the aircraft could and did.) Input from the audio sensors was also recorded and kept on tape. For several reasons, the Batcat crews simultaneously tracked and analyzed the sensor data they were relaying. Doing so maintained continuity if the link to NKP was lost or in case a Task Force Alpha computer or other piece of equipment crashed. In addition, several parts of the trail were outside the range of the relay equipment. At those locations, the aircrews processed the sensor signal data manually and called it in to 7th Air Force.
During the first two years of operation, the Batcats were flying daily missions, with each aircraft assuming flying 150 hrs per month in late 1968/ early 1969. Most of the EC-121R were returned to USA and storage by 1970, with nine aircraft remaining in the region until 1971, when they too were returned.
The EC-121R did a good job, but it was expensive to operate and it exposed a large crew to enemy fire. Consequently, it was replaced by a smaller airplane. The QU-22B Pave Eagle was a single-engine, propeller-driven aircraft, a modified Beech Model 36 Bonanza, designed to fly in either a manned or unmanned mode.