The Grumman-designed TBF/TBM Avenger series was the U.S. Navy’s principal torpedo plane from mid-1942 through the end of World War II—former President George Bush probably is the best-known Avenger pilot of that era. But in the immediate postwar period, the Avenger made a revolutionary contribution to naval warfare as the first airborne early warning (AEW) aircraft.
The catalyst for such aircraft was the unprecedented Japanese suicide attacks by Japanese kamikaze (divine wind) aircraft on the U.S. fleet off Okinawa in the spring of 1945. U.S. destroyers as radar pickets deployed to give warning of approaching Japanese aircraft were themselves the victims of kamikaze attacks that sank several destroyers and damaged many others. In response, the U.S. Navy developed submarine radar pickets (which could submerge after detecting an attacking enemy force) and airborne radar pickets.
Surface ship radars—limited to line of sight—could detect medium-altitude aircraft out to a maximum of perhaps 100 nautical miles, but low fliers could close to much shorter ranges before being detected. Surfaced submarine radars had shorter ranges and, of course, when the subs dived their radars were inoperative. A airborne radar with its inherent long- range capability seemed the best answer.
Designers had proposed installing a long-range search radar in a U.S. naval aircraft early in 1944 as a counter to low-flying Japanese torpedo bombers. Under Project Cadillac, a carrier-based TBM Avenger was fitted with an S-band—2 to 4 GigaHertz (GHz)—AN/APS-20 search radar. Its antenna—eight feet in diameter and rotating six times per minute—was fitted in a radome beneath the fuselage of the aircraft, which was redesignated the TBM-3W. At altitudes of 2,000 to 5,000 feet, the TBM-3W could detect a plane flying 500 feet above the water at a range of about 75 miles.
The cramped aircraft had room for a pilot and a single radar operator, whose scope was linked to those of surface ships by a VHF radio link. Air controllers on the ships in turn were to direct defending fighters and, when necessary, use the airborne Avenger to relay radio messages to the fighters. Detachments of TBM-3W aircraft went on board several carriers, but arrived too late to see combat. They were part of the world’s first operational AEW system, which employed data-link terminals on several ships.
The TBM-3W was followed by about 160 TBM-3W2 aircraft fitted with APS- 20 radars designed to detect the periscopes and snorkels of submerged submarines. These “hunter” aircraft teamed with TBM-3S “killers” in the antisubmarine role. TBM-3W2 aircraft subsequently served with Canadian, Dutch, French, and Japanese air forces. They became the progenitor of the AF-2S/AF- 2W Guardian “twins,” which served in the ASW role on board U.S. carriers. The last TBM-3W2, also the last U.S. Navy Avenger, was retired in 1956.
The next step in the AEW program— called Cadillac II—was to place a fighter-director team in the aircraft. The Avenger obviously was too small; after the war, the Navy fitted 23 ex-Army Air Force B-17G Flying Fortress bombers with the APS-20 and designated them PB-1Ws. These older aircraft, however, were not successful.
Still searching for the ideal aircraft, the Navy in 1949 fitted two four-engine Lockheed Constellations with an improved APS-20 in an under-fuselage radome and an APS-45 height-finding radar in a large dorsal radome. (These planes initially were designated PO-1Ws, subsequently changed to the WV-series and, in 1962, were redesignated EC- 12 Is.) The Navy bought 140 Connies and used them to establish the seaward extension, along with radar picket ships, of the North American Distant Early Warning (DEW) Line to provide warning of approaching Soviet bombers.
At the peak of the program, the Navy had 23 AEW aircraft assigned to fly patrols between Midway Island and Adak, Alaska, and another 16 planes operating over the North Atlantic from Argentina, Newfoundland. This AEW barrier remained in operation until late 1965.
The EC-12Is had 16 crew stations, including a combat information center (C1C) officer, five controllers, and five other electronic specialists. Twelve relief crewmen permitted 16-hour missions.
After the barrier shut down, the Navy continued to fly EC-121s in special surveillance and electronic intercept missions. The North Koreans shot down one of these aircraft over international waters on 14 April 1969, killing all 31 men on board. The last U.S. Navy Connie, an NC-121K, was retired in 1982.
But . . . back to the Navy requirement for a carrier-based AEW aircraft. The TBM-3W had no room for growth; in its place, the AD-3W variant of the ubiquitous Douglas Skyraider went aboard carriers. These AEW aircraft had a grotesque configuration with the APS-20 fitted in a large belly radome, which prompted the aircraft’s nickname: “Guppy.” The singleengine plane carried a pilot, radar officer, and enlisted radar technician; each U.S. carrier was provided with a four-plane AD-3W detachment. These specialized versions saw extensive combat in Korea and Vietnam. The Navy produced a total of 417 AEW versions of several Skyraider models, which flew until 1960.
The arrival of the larger Forrestal (CVA-59)-class carriers meant that bigger and more capable AEW aircraft could deploy aboard ship. Subsequently, the Grumman S2F Tracker ASW aircraft, powered by twin piston engines, was adapted to an AEW configuration as WF-2 Tracer (changed to E-IB in 1962). Known as the “Willie Fudd,” the WF-2 had a crew of four and was fitted with a saucer-shaped antenna for its APS-82 radar. Eighty-eight WF-2/E-1B Tracers were produced, and they served aboard carriers until 1977.
These were replaced by the improved Grumman W2F-1 (redesignated the E-2) Hawkeye, with twin turboprop engines, beginning in 1964. The Hawkeye has been periodically upgraded; the original APS-96 radar was succeeded by the APS-120 and, in the current, upgraded E-2C variant, the APS-125. The radar, with its rotodome-mounted rotating antenna, has an effective aircraft detection range of about 275 miles with an over-land/water capability. The aircraft can track simultaneously more than 250 air targets and control as many as 30 interceptors. Passive detection systems also are installed. These aircraft will fill the carrier-based AEW role for the foreseeable future, with production continuing. The Navy currently flies 68 E-2C variants, including nine flown by the Naval Air Reserve, plus two TE-2C trainers.
Land-based aircraft followed the early Navy programs. The U.S. Air Force operates the highly capable Airborne Warning and Control System (AWACS) E-3 series, and other nations operate AEW helicopters as well as fixed-wing AEW aircraft. But to the versatile TBM Avenger goes the accolade of being the world’s first AEW aircraft.