When U.S. aircraft carriers are at sea, on their flight decks—or flying nearby—are Grumman E-2 Hawkeye airborne early warning (AEW) aircraft. Radar-equipped planes have been flying from U.S. carriers in the AEW role for more than half a century.
The concept of AEW aircraft first was proposed in early 1944 as a counter to low-flying Japanese torpedo bombers. The ship-based Grumman–General Motors TBM Avenger was selected for the effort—called Project Cadillac—and was fitted with the S-band (2 to 4 GHz) AN/APS-20 search radar. The eight-foot antenna was installed in a radome beneath the fuselage. Once aloft, the TBM-3W could detect a plane flying 500 feet above the water at a range of 75 miles—and a battleship at a distance of some 200 miles.
The cramped TBM-3W could carry only one radar operator, in addition to the pilot. The operator would use a VHF data link to send information down to shipboard radarscopes. The ships then could direct fighters to intercept the approaching enemy aircraft, if necessary using the Avenger as a radio relay to the fighter aircraft.
The project received increased importance during the assault against Okinawa in April 1945, when U.S. destroyers positioned to give warning of Japanese air attacks were themselves the victims of kamikaze strikes, with several destroyers sunk and others damaged. In response, the Navy developed radar picket submarines (that could submerge after radar detection and vectoring in fighters) and airborne radar pickets—AEW aircraft.
As the war ended, the U.S. Navy was preparing to assign the extensively modified TBM-3W Avengers to carriers. The first four-plane AEW unit was to be ready by October 1945, with five more units to be available by 1 November. (At the time, the Pacific war was expected to continue at least into the spring of 1946.)
When the war did end in August 1945, planning was under way to provide large land-based AEW aircraft to also provide long-range radar surveillance in support of fleet operations. Several new Boeing B-17G Flying Fortress bombers were transferred to the Navy, reconfigured as AEW aircraft with the AN/APS-20 radar, and designated PB-1W. Most of these aircraft had the large belly radome, although a few aircraft mounted a radome above the fuselage. These four-engine aircraft initially were delivered to Patrol Bombing Squadron (VPB) 101 in the spring of 1946.
Soon after the war, in response to the building Soviet submarine threat, the Navy began employing several escort aircraft carriers (CVE) in the antisubmarine warfare (ASW) role. Each had a composite squadron of six TBM-3W and 12 TBM-3S Avengers. The “S”—for strike—aircraft carried rockets, depth bombs, and homing torpedoes. The AN/APS-20 radar in the “W” aircraft was considered effective for detecting submarine periscopes and snorkel masts.
The successor to the TBM-3W as a carrier-based AEW aircraft was the Douglas AD Skyraider, an attack aircraft—designed as a torpedo/dive bomber—that first flew on 18 March 1945.1 The AD-3W was the AEW variant. Flown by a crew of three, it provided more endurance and capability than the Avenger. It was fitted with the same, ubiquitous AN/APS-20 radar. In 1948, the Navy established Carrier Airborne Early Warning Squadrons (VAW) 1 and 2 to provide AD-3W detachments to carriers for both AEW and ASW operations, in daylight and at night. From 1952, the CVEs and light carriers (CVLs) employed in the ASW role operated the more-capable AD-4W and AD-4S Skyraiders.2
The AD-5W was an even more capable AEW variant. These Skyraiders were produced in large numbers: 31 AD-3W, 168 AD-4W, and 218 AD-5W variants. Fifty of the AD-4Ws were transferred to the British Royal Navy as Skyraider AEW Mark 1 aircraft; later, 14 of the British aircraft were sold to Sweden, but their AEW gear was removed and they had the depressing role of target tugs.
From 1960, the Fairey Gannet AEW Mark 3 replaced the Royal Navy’s Skyraiders; the turboprop Gannet also used the AN/APS-20. (The Skyraider-mounted AN/APS-20 radars later were fitted in the four-engine Avro Shackleton AEW Mark 2 aircraft.)
Subsequently, the ASW role on CVE/CVL flight decks was taken over by the so-called Guardian twins. The Grumman-built Guardian was the world’s first specialized ASW aircraft and the largest U.S. single-engine piston aircraft. Working in pairs, the AF-2W, with a large belly radome housing the AN/APS-20 radar and flown by a four-man crew, would search at low altitudes for hostile submarines, while the AF-2S or -3S teammate—flown by a three-man crew—would streak in, pinpoint the sub with its smaller AN/APS-30 or -31A radar (and searchlight at night), and attack with rockets, depth charges, or homing torpedoes. Although a relatively large aircraft—the AF-2S had a combat weight of 25,500 pounds—the plane flew mainly from escort carriers of the Commencement Bay (CVE-105) class. The first AF-series aircraft did not join fleet squadrons until October 1950 and served in front-line squadrons only until 1954 and in reserve units until early 1957. (The Guardian’s accident rate was relatively high; it was “definitely underpowered and completely unforgiving when coming aboard ship,” recalled Guardian pilot A. Jay Cristol.3)
The British disposal of U.S. carrier-based AEW aircraft led to the most critical shortfall of the Royal Navy during the 1982 conflict in the Falklands: the lack of airborne early warning aircraft. The British defense policy of 1966 led to the belief in some circles that land-based AEW aircraft, i.e., the turbojet Nimrod, could provide radar coverage for naval forces at sea. The Falklands war proved the fallacy of that view. The official Ministry of Defence report noted:
the absence of AEW was a severe handicap against Argentine air attacks mounted at very low level, especially at San Carlos where [shipboard] radars deployed suffered considerable interference from surrounding high land. The lack of AEW also proved an important limitation in the task force’s ability to deal with the threat from Exocet by intercepting the aircraft carrying it before the missile could be launched.4
The Falklands again demonstrated the value of carrier-based AEW aircraft.
In the U.S. Navy, the AEW effort was aided by the arrival of the Grumman S2F Tracker that combined both search and attack functions in a single airframe. It became the principal U.S. carrier-based ASW aircraft for the next two decades. The Tracker was a large—26,600-pound—twin-piston-engine, four-place aircraft. It was the ideal platform to carry the AN/APS-28 radar and, designated WF, became the Navy’s principal carrier-based AEW aircraft beginning in 1958.5 And, increasingly, these AEW aircraft were employed to vector defending fighters.
The WF—invariably referred to as the “Willie Fudd”—was succeeded by the twin-turboprop W2F Hawkeye.6 That aircraft, becoming operational in 1964, has undergone a series of radar upgrades. The original W2F-1 carried the AN/APS-96 radar mounted in a 24-foot-diameter rotating “saucer” or rotodome above the fuselage. The latest Hawkeye—the fourth major version—is the E-2D variant mounting the advanced AN/APY-9 radar. Compared to the previous Hawkeyes, the E-2D also has a new avionics suite, improved turboprop engines, and an in-flight refueling capability.
Airborne early warning aircraft are today being flown by more than a score of air forces, with land-based AEW platforms supported by Hawkeyes flown from U.S. and French aircraft carriers as well as from shore. In addition, several navies operate helicopters carrying AEW radar. Although satellites and unmanned aerial vehicles increasingly provide long-range “eyes” for navies, manned AEW aircraft will continue to be important for determining “what’s out there.”
1. The AD series was changed to A-1 in the military-wide redesignation scheme adopted in 1962.
2. While serving in the ASW role, these ships were informally referred to as CVEK and CVLK.
3. Capt. A. Jay Cristol, USNR (Ret.), telephone conversation with N. Polmar, 21 February 2006.
4. Secretary of State for Defence, The Falklands Campaign: The Lessons (London: December 1982), 21.
5. The WF was redesignated E-1 in 1962.
6. The W2F was redesignated E-2 in 1962.