Boeing E-3 Sentry

Updated: October 2026 – A gray four-engine jet drifts low over the fields near Teveren, a huge, flat disc on its back: that is a Boeing E-3 Sentry, probably the best-known flying radar in the world. Since the late 1970s it has been the symbol of “AWACS,” and for many spotters in western Germany it is almost an everyday sight. Here you will learn how the E-3 came about, what sets it apart technically, which countries fly it, how to tell the versions apart and what comes next for the type.

What is the Boeing E-3 Sentry?

The E-3 is an AWACS aircraft – Airborne Warning and Control System. Such aircraft circle at high altitude over an area of operations, use their radar to detect airplanes, helicopters and cruise missiles over a wide radius, and direct friendly jets, tankers and transports. In essence, the E-3 is a flying radar station with an integrated air control center.

The aircraft underneath is an old acquaintance: a Boeing 707-320B, the long-haul design with which Boeing ushered in the jet age in scheduled service in the 1950s. The story of the airliner is told in the article Boeing 707. For the E-3 the fuselage was completely rebuilt inside, strengthened and fitted with the distinctive radar dome. You can find more about the manufacturer on the Boeing page.

A total of 68 aircraft were built between 1977 and 1992. The civilian 707 had long since ended production by then; the AWACS aircraft were – alongside military sister models like the E-6 – among the last 707 airframes Boeing built at all.

Origins: a radar that looks down

In the late 1960s the US Air Force wanted to replace its aging early warning aircraft based on the Super Constellation. Their radars had a fundamental problem: over land, low-flying targets got lost in the ground clutter. What was needed was a radar with “look-down” capability that reliably detects an aircraft against a background of terrain – and a platform that stays airborne long enough.

Boeing won the competition by proposing the 707 as the platform. Two radar manufacturers competed with prototypes, and Westinghouse won the race with a pulse-Doppler radar. The first test aircraft, designated the EC-137D, made its first flight on February 9, 1972. From 1975 the systems were tested together, and in March 1977 the US Air Force took delivery of its first E-3 at Tinker Air Force Base in Oklahoma.

Technology: what is inside the E-3

From the outside the dome is what counts, but inside the E-3 is a complete command post. The key points:

• Rotodome: The radar dome is about 9.1 meters in diameter, about 1.8 meters thick in the middle and sits on two struts a good three meters above the fuselage. In operation it rotates about six times a minute, and its leading edge is tilted slightly downward to reduce drag.
• Radar: Under the hood works a pulse-Doppler radar of the AN/APY-1/APY-2 family. It detects low-flying targets at more than 400 kilometers, and aircraft at medium and high altitude in an additional mode at a considerably greater distance. The dome also houses the antenna for the identification friend or foe system.
• Engines: The USAF and NATO aircraft fly with four Pratt & Whitney TF33-PW-100A engines of about 96 kN thrust each. Saudi Arabia, the UK and France chose the more economical CFM56, which brings more range and endurance. You can find more about the manufacturers at Pratt & Whitney and CFM International.
• Crew: Four people sit on the flight deck up front, and in the back, depending on the mission, 13 to 19 specialists man consoles for surveillance, weapons control and communications.
• Endurance: Without aerial refueling a TF33 E-3 stays airborne for more than eight hours, with CFM56 engines about eleven hours. With refueling it is extended, limited mainly by the crew.

Versions and upgrades

Because the E-3 has been in service for almost five decades, there are quite a few designations. For spotters this is helpful because operator and engine can be derived from them:

Version	Operator	Engine	Note
E-3A	NATO, Saudi Arabia, initially USAF	TF33 (NATO), CFM56 (Saudi Arabia)	first production version
E-3B / E-3C	US Air Force	TF33	modernized US standards
E-3G	US Air Force	TF33	current US standard after Block 40/45
E-3D (Sentry AEW1)	Royal Air Force, now Chile	CFM56	retired in the UK in 2021
E-3F	France	CFM56	four aircraft at Avord

The most important upgrades came in stages. The Block 30/35 package brought electronic surveillance sensors, Link 16 and GPS from the late 1980s. The Radar System Improvement Program (RSIP), launched jointly by the US and NATO, improved the radar’s sensitivity; the UK and France followed. With Block 40/45 the US aircraft received new central computers and consoles from the 2010s, which gave rise to the E-3G designation.

NATO went its own way: from 2019, among other things, it renewed the cockpits with screens and is modernizing mission and communications systems with the Final Lifetime Extension Programme (FLEP). According to NATO, the program is worth about one billion US dollars and is meant to keep the fleet operational until 2035.

The operators at a glance

US Air Force

With 34 aircraft the USAF was the largest customer. The fleet’s home is Tinker Air Force Base in Oklahoma, plus squadrons at Kadena in Japan and Elmendorf in Alaska. Since 2023 the Air Force has been significantly reducing its E-3 fleet to free up money for the successor. The planned procurement of the Boeing E-7 Wedgetail was canceled in Washington for a time and was politically revived in 2026; quantities and schedule were not yet finally settled in October 2026. How US serial numbers are structured is explained in the article US military serials.

The USAF suffered the type’s worst accident on September 22, 1995: shortly after takeoff at Elmendorf, an E-3 flew into a flock of Canada geese, two engines failed, and all 24 people on board were killed.

NATO

The NATO fleet is one of a kind: 18 E-3A that belong to the alliance jointly and are flown by mixed crews from many member states. The procurement was decided in December 1978, with deliveries between 1982 and 1985. The E-3A Component is considered the alliance’s first multinational flying unit. The aircraft are registered in Luxembourg, hence the registrations with the prefix LX-N.

The home base is NATO Air Base Geilenkirchen (ICAO: ETNG) near Teveren, right on the Dutch border. In addition there are forward operating bases at Konya (Turkey), Aktion (Greece) and Trapani (Italy) and a base at Ørland in Norway. One aircraft was lost in 1996 in a rejected takeoff at Aktion, and three more were retired. Today the fleet comprises 14 E-3A.

The NATO AWACS were deployed, among other places, over the US after September 11, 2001, over the Balkans, over Libya in 2011 and in Afghanistan. Since 2014, and increasingly since 2022, they have been monitoring the airspace on the alliance’s eastern flank.

France

France operates four E-3F with CFM56 engines, independent of the NATO fleet. They are based at Base aérienne 702 in Avord in the Cher department. Since entering service around 1990 they have been modernized several times, including with the RSIP radar upgrade. At the end of 2025 France ordered two Saab GlobalEye with an option for two more; delivery is planned for 2029 to 2032, and until then the E-3F stays in service. What applies when photographing in France is summarized in Photographing at French airports.

Saudi Arabia

The Royal Saudi Air Force ordered five E-3A in 1983, delivered in the second half of the 1980s – unlike the US and NATO aircraft, with CFM56 engines. From 2013 the aircraft also received the RSIP radar upgrade. This makes Saudi Arabia one of the operators whose E-3s are still active; details on the fleet’s future are hardly public.

United Kingdom and Chile

The Royal Air Force flew seven E-3D, officially Sentry AEW1, from RAF Waddington. Externally they stood out with sensor pods at the wingtips and an additional refueling probe above the cockpit. The last flight in British service took place in August 2021, earlier than originally planned. The successor is the E-7 Wedgetail. Three of the British aircraft went to Chile, where they arrived in 2022; two of them are intended for flight operations, and the third is considered a source of spare parts.

How to identify the E-3

With a radar dome the job is almost done – now it is only about platform and operator.

General tips on early warning and surveillance types can be found in Identifying AWACS, maritime patrol and surveillance aircraft.

The E-3 and its look-alikes

Feature	E-3 Sentry	E-767	E-7 Wedgetail	KC-135
Base aircraft	707-320B	767-200ER	737-700	own design, related to the 707
Engines	4	2	2	4
Radar	round dome	round dome	flat blade	none
Refueling boom	no	no	no	yes

The biggest risk of confusion is with the E-767, because the dome is practically identical – the number of engines settles it immediately. Without a dome a gray four-engine jet quickly looks like an E-3 but is often a KC-135 or an RC-135: this family is shorter and has a different fuselage shape, even though it is related to the 707. The US Navy’s E-6 Mercury also uses the 707 airframe but has no dome. And the E-2 Hawkeye does carry a radar dome but is a much smaller propeller aircraft.

Where to see the E-3

In Europe the answer is clear: Geilenkirchen. The entire NATO fleet takes off and lands on the single runway 09/27. According to spotters’ experience, flying mostly takes place on weekdays, with a few missions a day and long pauses in between being typical. There is no public flight schedule.

Place	Chance of a hit	Why
NATO Air Base Geilenkirchen	high	Home base of all 14 NATO E-3A
BA 702 Avord, France	good	Home of the four E-3F
Major airshows and air days	occasional	E-3 as a static display, for example at RIAT
Tinker AFB, USA	high	Main base of the US fleet
Forward NATO bases	occasional	Konya, Aktion, Trapani, Ørland

You can find all locations, focal lengths and wind rules for Geilenkirchen on the spot page Teveren spotters’ hill, and background on the base in Plane spotting in Geilenkirchen. With a westerly wind, operations usually run on runway 27, and with an easterly wind on 09 – before you set off it is worth checking the wind forecast.

A good way to get close-ups is air days: at the Royal International Air Tattoo in Fairford E-3s have been on static display several times, and at the air force open days presented in the article Bundeswehr Day the NATO fleet is occasionally represented. Whether an E-3 is among them only becomes clear at short notice in the official participant lists.

You can track the E-3 on the go only to a limited extent: many military flights do not transmit ADS-B continuously, and callsigns change. How to get an overview anyway is shown in Tracking military aircraft online.

Photo tips for the fence and the airshow

• Look for the side profile: Dome, struts and the long 707 fuselage look best in profile. Landings are ideal because the E-3 flies slowly and steadily then.
• Adjust the exposure: A gray fuselage against a bright sky quickly turns out too dark. A slight plus correction helps without blowing out the bright dome.
• Keep the registration legible: With 14 NATO aircraft, every LX-N registration is a collectible of its own. Make sure it stays readable on the tail.
• Catch the smoke: The old TF33s leave visible exhaust trails behind them on takeoff – a detail that will disappear with the fleet’s replacement.
• Plan the light: When the sun suits your vantage point is explained in Planning the sun position for your photo spot.

Retirement and succession

The E-3 is a type in transition. The UK retired it in 2021, and the US has been shrinking its fleet since 2023. For NATO, the E-7 Wedgetail was initially selected as the successor in 2023, with six aircraft to be procured. After the US had temporarily called its own E-7 plans into question, the participating countries moved away from it in 2025 and looked for alternatives.

Then, at the NATO summit in Ankara on July 7, 2026, eleven countries – Belgium, Denmark, Germany, Canada, Latvia, Lithuania, Luxembourg, the Netherlands, Norway, Romania and Sweden – announced that they would jointly procure up to ten Saab GlobalEyes. The GlobalEye is based on a business jet of the Bombardier Global 6000 family, comes from the Swedish manufacturer Saab and carries an elongated radar blade instead of a dome. Saab stressed that no contract has been signed yet; negotiations are running through the NATO procurement agency. Where the new aircraft will be permanently based had not been conclusively settled publicly as of October 2026. In the long term NATO wants to replace the E-3A with a whole network of sensors; the current fleet is meant to fly until about 2035.

Conclusion

The E-3 Sentry has shaped the idea of what a flying radar looks like: a gray 707 with a dome on its back. Almost five decades after the first delivery it still flies with several operators, but the successors are decided or on order. For spotters this means: the time to experience the E-3 with its smoking TF33s at the fence is limited – and Geilenkirchen is the best place for it in Europe.