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.