Boeing E-3 D Sentry

What is the Boeing E-3 Sentry?

The Boeing E-3 Sentry is an airborne early warning and control aircraft, better known as AWACS, short for Airborne Warning and Control System. It is a heavily modified Boeing 707-320B with a rotating radar dome on its back.

Boeing built 68 E-3s between 1977 and 1992. The U.S. Air Force, NATO, France and Saudi Arabia fly them, and Chile bought three retired Royal Air Force aircraft.

The specification panel on this page describes the E-3D, the Royal Air Force’s CFM56-powered Sentry AEW1. Where the American and NATO aircraft differ, the sections below say so.

What does an E-3 Sentry do?

A Sentry watches the sky and tells fighters where to go. Its radar surveys airspace from the surface up into the stratosphere, over land or sea, and the crew inside identifies, tracks and directs the aircraft it finds.

The radar can see low-flying aircraft by filtering out the ground clutter that confuses other radars. A maritime mode uses very short pulses to detect ships.

The aircraft also moves, which a ground radar cannot do. The U.S. Air Force says that mobility gives a Sentry a better chance of surviving a war than a fixed site, because its flight path can be changed quickly.

E-3s were among the first aircraft to deploy for Operation Desert Shield, and they controlled air operations over Serbia in 1999 and against ISIS in Operation Inherent Resolve. The Air Force also sent them to coordinate rescue efforts after Hurricanes Katrina and Rita.

How the rotodome and radar work

The rotodome is 30 feet (9.1 m) across and 6 feet (1.8 m) thick, and two struts hold it 11 feet (3.3 m) above the fuselage. It is not pressurized, and its front edge is tilted down to cut drag.

The radar inside is the Northrop Grumman AN/APY-1 or AN/APY-2, and the Air Force credits it with a range of more than 250 miles (400 km). The dome turns six times a minute while the radar works and once every four minutes when it does not.

The radar has several modes. One scans for airborne targets without measuring their height, one adds elevation to find altitude, and one listens passively without transmitting.

From Boeing 707 to AWACS: how the E-3 was built

On July 23, 1970, the U.S. Air Force chose the 707-320 airliner as the base airframe for a new warning aircraft. Boeing had first proposed a purpose-built design with eight General Electric TF34 engines, but tests showed it would not outperform the 707 that was already flying.

Two EC-137D prototypes flew in 1972, one carrying a Westinghouse radar and one a Hughes radar. A fly-off from March to July 1972 ended with the Air Force choosing Westinghouse.

The first E-3 flew on May 25, 1976. The first aircraft reached Tinker Air Force Base, Oklahoma, in March 1977, initial operating capability followed in April 1978, and the 34th and last Air Force Sentry arrived in June 1984.

Turning an airliner into a radar platform meant more than adding a dome. Boeing uprated the hydraulics to turn the rotodome, added air-to-air refueling and fitted a bail-out tunnel for the crew.

E-3A, E-3B, E-3C, E-3D, E-3F and E-3G: what the letters mean

The suffix tells you the build standard or the customer. The original E-3A had Pratt & Whitney TF33 engines and the AN/APY-1 radar, and it served with the Air Force and NATO.

The Air Force labels its aircraft by upgrade standard: E-3B for Block 30 and E-3C for Block 35. The E-3C carries the AN/APY-2 radar and extra consoles.

The E-3G is the Block 40/45 upgrade, which began in 2014 and replaced the 1970s mission computers. It also brought a digital cockpit, and Air & Space Forces Magazine lists the E-3B and E-3G as the active variants.

The E-3D is the RAF’s version, and the E-3F belongs to France, which has four. Both use CFM56 engines. Saudi Arabia’s five E-3As use them too.

Not every AWACS is an E-3. Japan’s E-767 puts the same mission system on a Boeing 767.

The E-3D: the RAF’s seven Sentries

Britain came to the E-3 by accident. Its home-grown Nimrod AEW3 first flew in July 1980 but suffered technical problems that its builders could not fix, and it was cancelled in early 1987. The Ministry of Defence then ordered seven E-3s.

In RAF service the aircraft was officially the Sentry AEW.Mk 1, though crews and enthusiasts called it the E-3D. Its CFM56 engines set it apart from the U.S. aircraft, and it could take fuel from hose-and-drogue tankers.

No. 8 Squadron received its first E-3D at RAF Waddington, Lincolnshire, in July 1991. Little more than a year later the type was flying over the Balkans, and in 1994 it contributed to Operation Warden over northern Iraq.

It was still flying combat-support missions in 2015, when an E-3D deployed to Cyprus to support coalition strikes on Islamic State targets.

The fleet shrank as money ran out. The UK dropped its Project Eagle upgrade in 2009, which would have brought the aircraft to the U.S. Block 40/45 standard.

By December 2020 only two aircraft were available for operations at any one time, according to AirForces Monthly. The RAF retired the type in 2021, and Chile bought three of the retired aircraft.

The RAF’s replacement is the Boeing E-7 Wedgetail, on a 737 airframe. A 2021 defense review cut the British order to three aircraft.

Explaining the numbers

The full specification table for the aircraft is on this page. A few of its figures need context, because the sources that publish them describe different aircraft.

Start with the engines. The E-3D’s four CFM56-2A3 turbofans produce 24,000 lbf (107 kN) each, according to the RAF. U.S. and NATO aircraft use TF33 turbofans that sources rate between 20,500 and 21,500 lbf.

The CFM56 also explains the longer legs. The Air Force quotes about 8 hours of unrefueled endurance for its TF33 aircraft, while the RAF lists 10 hours for the E-3D and Airforce Technology says the CFM56 versions can reach 11 hours.

Range is less useful than it sounds. A Sentry matters for how long it can stay on station, and crews extend that by refueling in flight and working in shifts.

Speed is the muddiest figure. The RAF lists a cruising speed of Mach 0.72 for the E-3D, and the Air Force lists an optimum cruise of 360 mph (Mach 0.48) for its aircraft.

Neither source says what each speed means, so treat them as published figures and not as a performance envelope. The panel’s maximum speed is the figure the page has carried for years, and no E-3D source confirms it.

Altitude has the same problem. The RAF gives the E-3D a service ceiling of 43,000 ft (13,100 m), while the Air Force says only “above 29,000 feet”, which reads as a minimum and not a limit. Airforce Technology notes that the CFM56 engines let the aircraft fly higher, which extends the radar horizon.

Weight depends on the source too. The Air Force fact sheet gives a maximum takeoff weight of 325,000 pounds (147,418 kg) for its TF33 aircraft, and the Federation of American Scientists lists 347,000 pounds (156,150 kg). The panel carries the RAF’s E-3D figure.

Who flies the E-3: crew and mission stations

The flight crew is four: two pilots, a navigator and a flight engineer. Behind them sits a mission crew of 13 to 19 specialists, depending on the job, which is why the panel counts up to 23 people aboard.

Those specialists run surveillance, identification, weapons control, battle management and communications from consoles in the cabin. A crew rest area lets the team work in shifts on long missions.

The E-3G(II) upgrade added a glass cockpit that reduced the crew size by one.

E-3 Sentry accidents and losses

On September 22, 1995, an Air Force E-3 with the callsign Yukla 27 crashed shortly after taking off from Elmendorf Air Force Base, Alaska. It ingested Canada geese, lost power on both left-side engines and went down about 2 miles (3.2 km) northeast of the runway, killing all 24 people aboard.

On July 14, 1996, a NATO E-3A overran the runway at Preveza-Aktion in Greece. The pilot aborted the takeoff after wrongly believing the aircraft had hit a bird, and nobody was hurt.

On August 28, 2009, an Air Force E-3C collapsed its nose gear on landing at Nellis Air Force Base, Nevada, during a Red Flag exercise. A fire followed and the aircraft was damaged beyond repair, but all 32 crew members got out.

On March 27, 2026, an Iranian drone and missile strike destroyed an Air Force E-3G on the ground at Prince Sultan Air Base in Saudi Arabia during the 2026 Iran war. Flight-tracking data showed six E-3s had been stationed there, and an unnamed U.S. official told NPR that a second E-3 was also damaged.

How many E-3 Sentries are still flying in 2026?

The U.S. Air Force cut its fleet to 16 aircraft in fiscal 2023, retiring roughly half of it, and then lost one in the March 2026 strike. Air & Space Forces Magazine put the fleet’s mission-capable rate at about 56 percent in fiscal 2024.

The fiscal 2026 defense bill barred the Air Force from retiring or mothballing any of the 16. On June 5, 2026, the House Armed Services Committee approved an amendment to the fiscal 2027 bill that would extend that ban through 2027 and lower the required minimum from 16 to 15, to account for the loss.

NATO flies 14 E-3As from Geilenkirchen, Germany, out of the 18 it bought. France operates four E-3Fs, Saudi Arabia five E-3As and Chile three ex-RAF E-3Ds.

The picture is still changing. The figures above are the latest confirmed ones, from June and July 2026.

What replaces the E-3?

The U.S. Air Force chose the 737-based E-7 Wedgetail, and Air & Space Forces Magazine reports a $1.2 billion contract to adapt it. The first of 26 planned aircraft slipped to 2028, and the Air Force tried to cancel the program in fiscal 2026 before Congress restored its funding.

The Pentagon’s leadership has also voiced support for relying more on space-based systems. Congress has pushed back, and the June 2026 amendment would require the Air Force to certify that moving from E-3s to E-7s would not degrade early warning or battle management coverage.

NATO went a different way. At its summit in Ankara in July 2026, Secretary General Mark Rutte announced that a group of allies would buy up to ten Saab GlobalEye aircraft, built on Bombardier Global airframes.

That fleet will not replace the 14 E-3As one for one, and Saab said negotiations were still to come. France ordered two GlobalEyes of its own in December 2025, with deliveries due between 2029 and 2032.

The Navy’s equivalent, the smaller turboprop E-2 Hawkeye, does the same job from aircraft carriers.

Frequently Asked Questions

How many E-3 Sentries does the US have?

The U.S. Air Force had 16 E-3s before the March 27, 2026 strike on Prince Sultan Air Base destroyed one. Congress’s proposed minimum fleet size for fiscal 2027 is 15.

What aircraft is the E-3 Sentry based on?

The E-3 is built on the Boeing 707-320B airliner. The Air Force picked that airframe on July 23, 1970, and added the rotodome, stronger hydraulics and air refueling.

What is a Boeing E-3B Sentry used for?

The E-3B does the same job as every Sentry: airborne surveillance, command and control, and battle management. The letter marks its upgrade standard, the Block 30 modification, and not a different role.

What is the difference between an E-3 Sentry and an E-3D?

The E-3D is the Royal Air Force’s version, with CFM56 engines in place of the TF33 turbofans on U.S. and NATO aircraft. The RAF retired its E-3Ds in 2021, and Chile bought three of them.

What plane does JD Vance fly on?

The vice president flies on the C-32, the Air Force’s version of the Boeing 757-200, under the call sign Air Force Two. It is not an E-3. The Air Force bought the C-32 to replace its aging C-137 fleet.

How big is the E-3 Sentry’s radar dome?

The rotodome is 30 feet (9.1 m) in diameter and 6 feet (1.8 m) thick. It sits 11 feet (3.3 m) above the fuselage on two struts.

How much does an E-3 Sentry cost?

The Air Force lists a unit cost of $270 million in fiscal 1998 constant dollars. That is not today’s price, because the type has been out of production since 1992.

Is the E-3 Sentry still in service?

Yes. The U.S. Air Force, NATO, France, Saudi Arabia and Chile all still fly E-3 Sentries as of mid-2026, though the U.S., NATO and France have all announced successors. The RAF retired its E-3Ds in 2021.