The Navy’s earlier carrier radar aircraft, such as the Grumman E-1 Tracer derived from the S-2 Tracker, carried their antenna in a fixed radome and had limited range and processing. For the Hawkeye, Grumman started with a clean sheet and the hard limits of a carrier. The aircraft had to fit on the catapult and arresting gear, fold small enough for deck parking and hangar stowage, and carry a large rotating antenna above the fuselage where it would see in every direction.

The answer was a high-wing twin turboprop with wings that swing back and fold alongside the fuselage, a tail with four vertical surfaces to give enough fin area without excessive height, and a rotodome on a pylon that can be lowered by about 60 cm to clear hangar decks on older carriers. The same basic layout, without the radar, became the C-2 Greyhound carrier transport. The basic shape has hardly changed since 1960; almost everything inside it has been replaced more than once.

Israel was the Hawkeye’s first export customer, buying four E-2Cs, and used them to devastating effect over Lebanon in 1982. Japan’s interest was sharpened in September 1976, when Soviet pilot Viktor Belenko flew a MiG-25 at low level into Hakodate, exposing gaps in Japanese radar coverage; the Japan Air Self-Defense Force went on to buy 13 E-2Cs and has since added E-2Ds. Egypt and Singapore each bought E-2Cs in the late 1980s, and Taiwan acquired four E-2T aircraft in 1995.

France bought E-2Cs for its nuclear carrier Charles de Gaulle, the only non-US carrier able to operate the type, and has ordered E-2Ds to replace them, with production of the first French aircraft under way by the end of 2024. Mexico’s navy acquired three former Israeli E-2Cs in 2004. Singapore later replaced its Hawkeyes with Gulfstream-based aircraft, and Israel retired its fleet, but the type remains in front-line service on three continents.

The E-2A’s early computer and radar were troublesome, and most were rebuilt as the E-2B with a better computer from 1969. The E-2C, first flown on 20 January 1971, brought a new radar able to track targets over land and a passive detection system, and was improved in successive groups through the 1980s and 1990s. Later upgrades added eight-bladed NP2000 propellers, which reduced vibration and noise, and the Hawkeye 2000 mission system with new computers and the Cooperative Engagement Capability that lets ships fire at targets tracked by the aircraft.

The E-2D Advanced Hawkeye, first flown in August 2007, replaced the radar with the APY-9, added a glass cockpit and uprated engines, and later gained an air-to-air refuelling probe so it can stay on station well beyond its unrefuelled endurance of around six hours. It reached initial operating capability in October 2014.

• W2F-1 / E-2A: original production version, in service from 1964.
• E-2B: E-2As rebuilt with a new computer from 1969.
• E-2C: new radar and passive detection system, first flown 1971, in service 1973; built in successive groups.
• E-2C Hawkeye 2000: new mission computer, workstations and Cooperative Engagement Capability.
• E-2T: Taiwanese E-2Cs, later upgraded to Hawkeye 2000 standard.
• E-2D Advanced Hawkeye: APY-9 radar, glass cockpit, air-to-air refuelling; first flight 2007.
• C-2 Greyhound: carrier transport derivative sharing the wing and engines.

Compared with land-based airborne early warning jets, the Hawkeye is cheap to run: two turboprops, a crew of five and a small airframe. Northrop Grumman stresses its smaller logistical footprint. But carrier operations are hard on aircraft, with catapult launches, arrested landings, salt air and cramped maintenance, and the E-2D’s radar and mission systems are complex.

No authoritative public cost per flight hour was found for this page, so the figure given is an order-of-magnitude estimate only. The E-2C’s US Navy unit cost was given as US$80 million; the E-2D is considerably more expensive.