AWACS — Airborne Warning and Control System — is a flying radar station that extends the detection horizon by altitude, tracks thousands of contacts at once, and acts as the air battle's command node. The radar matters, but the mission crew behind it matters just as much.
See the E-3 Sentry in the galleryA surface-based radar at sea level can detect a target flying at 100 ft above the sea out to roughly 23 nautical miles before the Earth's curvature hides it. Lift the radar to 30,000 ft and that same target becomes visible out to about 230 nm. AWACS flies high to push the horizon as far out as physics allows, then uses a powerful radar to see across that horizon.
The original 1960s requirement that produced the E-3 Sentry was specifically to look down through ground clutter and see low-flying Soviet bombers approaching North America under conventional radar coverage. That problem framed the entire AWACS concept: the radar has to filter ground returns far better than a surface radar would need to.
The radar is the headline feature, but a modern AEW&C platform performs several jobs at once:
A typical E-3 mission crew is 13-19 people including the flight crew. The Wedgetail and Hawkeye run smaller crews thanks to digital workstations and more automation.
The E-3 Sentry first flew in 1972 and entered USAF service in 1977. Its airframe is the Boeing 707-320B; its radar is the AN/APY-1/2, a pulse-Doppler S-band system mounted in a 30-foot-diameter rotodome 11 feet above the rear fuselage. The rotodome spins at 6 rpm in operation and 1/4 rpm when the radar is off, to keep the bearings lubricated.
The AN/APY-2 detects fighter-sized targets at 250 nm and bomber-sized at 400 nm. Endurance with internal fuel is 8 hours; air refuelling extends this to 12+ hours. The airframe has been upgraded through Block 40/45 with new mission computers, but the basic 707 platform is 60 years old. USAF E-3 retirement runs through the late 2020s, replaced by the E-7. NATO retains 14 E-3As at Geilenkirchen, Germany, with a planned retirement around 2035.
The AN/APY-2 antenna is a planar array inside the rotodome. The array is electronically scanned in elevation but mechanically scanned in azimuth by the rotodome's 6 rpm rotation. This gives 360-degree coverage every 10 seconds. A modern AESA replaces the mechanical scan entirely — which is exactly what the E-7 does.
The E-7 Wedgetail is a 737-700ER-based AEW&C aircraft with a flat dorsal "top hat" antenna mounting the Northrop Grumman MESA (Multirole Electronically Scanned Array). MESA is a true electronically-scanned L-band/UHF AESA with no moving parts — beams steer in microseconds, the array covers a 240-degree primary azimuth arc plus side-looking coverage filling the gaps.
The Royal Australian Air Force ordered six in 2000 and accepted them between 2009 and 2012. Turkey took four (Peace Eagle), South Korea four (Peace Eye), the UK ordered three E-7A in 2019, and the USAF placed orders in 2022 to replace the E-3. Detection range against fighter-sized targets is broadly comparable to the AN/APY-2 — 200-300 nm — but the electronic scan delivers track updates every second on selected targets rather than every 10 seconds.
Other Wedgetail advantages over the E-3: roughly 30% lower fuel burn, half the mission crew (typically 6-10 operators), modern open-architecture mission systems, and a glass cockpit. NATO is examining the E-7 as a longer-term replacement for its A-model Sentries.
Carrier decks cannot launch a 200,000 lb 737. The US Navy's airborne early-warning aircraft is the E-2D Advanced Hawkeye — a 58,000 lb twin-turboprop with a 24 ft rotodome over the rear fuselage. The radar is the AN/APY-9 UHF-band AESA, electronically scanned in azimuth, with the rotodome rotating only for mechanical-scan back-up.
The UHF wavelength (around 70 cm) is significantly longer than X-band and gives the AN/APY-9 a degree of counter-stealth capability — the longer wavelength scatters from stealth aircraft features in a way short-wave radars cannot. Detection range against air targets is reported at 200+ nm. The E-2D replaced the AN/APS-145 mechanical radar of the older E-2C and entered fleet service in 2014; current Block II adds aerial refuelling, taking on-station time from 4 to 7+ hours.
The E-2D is also the centrepiece of the Navy's Naval Integrated Fire Control - Counter Air (NIFC-CA). The Hawkeye datalinks high-quality tracks to Aegis cruisers and destroyers, allowing them to launch SM-6 missiles at over-the-horizon targets the ships cannot see themselves.
The Soviet response to the E-3 was the Beriev A-50 Mainstay, an Il-76 four-engine airlifter with a Vega-M rotodome radar. The A-50 entered service in 1985; the upgraded A-50U with digital mission systems flew in 2011. Approximately 9 of the upgraded variant remain in Russian service after two A-50s were lost in 2024 — one to a Ukrainian SAM and one possibly to friendly fire.
The replacement A-100 Premier — an Il-76MD-90A airframe with an active electronically scanned dual-band array — was first flown in 2017 but has been beset by export-component embargoes since 2022. Series production has been repeatedly slipped; only a single prototype is known to fly.
The Chinese AEW&C programme moved straight to AESA. The KJ-2000, mounted on an Il-76 airframe, was the first PLA AWACS and entered service around 2003 with a phased-array radar in a fixed triangular dome. Four were built — the line stopped when Russia refused to supply more airframes after Israel cancelled the Phalcon export over US pressure.
The KJ-500, on a Y-9 (An-12 derivative) turboprop, took over from around 2015 and is the most-produced PLA AEW&C with at least 30 built. It carries a fixed three-sided AESA in a circular dome. The newer KJ-3000 is mounted on the Y-20 widebody airlifter and is expected to be the principal long-range PLA AWACS through the 2030s.
The Swedish Erieye system uses a different antenna shape: a long dorsal beam (the "balance beam") mounting two back-to-back PESA arrays that look left and right but not directly forward or aft. The compact size let Saab fit the radar to small turboprops — the Saab 340 AEW&C (Argus), the Embraer R-99 (Brazil, Greece, Mexico), and the Bombardier Global 6000-based GlobalEye (UAE, Sweden).
GlobalEye combines an upgraded Erieye ER (extended-range S-band AESA) with maritime surface-search and ELINT sensors on one platform. The UAE ordered three in 2015; Sweden ordered two as Erieye replacements in 2022; France ordered two in 2024 to bridge to a future European AEW solution. Detection range against fighter-sized targets is reported at 250-400 nm depending on geometry.
The Israeli approach abandons the rotodome and balance beam entirely. The IAI/Elta CAEW (Conformal AEW), known to the IAF as Eitam, is built on a Gulfstream G550 business-jet airframe. The radar is the EL/W-2085 — a four-faced L-band AESA mounted in conformal cheek fairings and small fore/aft additions. The whole thing weighs less than a rotodome and adds far less drag, giving the aircraft 10+ hours endurance at 41,000 ft. See the IAI Shavit / G550 CAEW entry for the conversion detail.
The Eitam entered IAF service in 2008 (two aircraft); the same conformal architecture has been exported to Italy (CAEW), Singapore, and Israel's own AF for follow-on aircraft. The configuration is widely seen as the template for any future Gulfstream- or 737-MAX-based AEW conversion.
An AWACS is a 250,000 lb subsonic radar that broadcasts a signal detectable to passive ESM receivers at twice the radar's own detection range. The R-37M long-range Russian air-to-air missile was explicitly developed to threaten AWACS — its Mach 6, 510 kg airframe and 200+ km claimed range mean an AWACS orbit 250 nm from a hostile coastline is no longer safe. The same risk applies to PL-15 and the ramjet Meteor.
The response, partly already in service, is distributed networked sensing. Instead of one radar on one large aircraft, multiple smaller sensors share data: F-35s in a CAP relay each other's tracks via MADL, AESAs on F-22s and Super Hornets fuse their pictures, the E-2D and surface ships feed into the same air picture via NIFC-CA. If an AWACS goes down, the picture survives. The AEW&C aircraft remains the most efficient single sensor — but it is no longer expected to be the only one.
Content adapted from publicly available aeronautical engineering and defence references. Vehicle data sourced from the Who That Plane?! gallery.