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U.S. Air Force Improving AWACS Capabilities

The U.S. Air Force is pressing ahead with the largest block upgrade in the long history of the E-3B/C Sentry, the Airborne Warning and Control System (AWACS) aircraft.

The first airframe modified to the latest block 40/45 configuration arrived November 18 at Tinker Air Force Base (AFB), Okla. Most AWACS planes in inventory belong to the 552nd Air Control Wing at Tinker and are among the “most deployed” assets in the U.S. military. Tinker’s Oklahoma City Air Logistics Center oversees depot maintenance for all 32 aircraft in the AWACS fleet.

Today, Boeing is providing a new mission computer and other hardware for the first aircraft to be upgraded, along with spare parts and other services.

Remarkably, the AWACS fleet had been relying on a mission computer that dates to the inception of the aircraft. The first plane in the series, then called the EC-137D, completed its maiden flight on Feb. 5, 1972 without full missions systems. The missionized, production-standard E-3A made its first flight on October 31, 1975, and while AWACS has seen a series of sustainability and reliability upgrades over many years, some key components were never changed. The current fleet includes 22 E-3B models, upgraded from E-3A standard with jam-resistant communications and avionics improvements, plus 10 E-3C aircraft with additional radio, console and radar capabilities.

Today, Boeing is providing a new mission computer and other hardware for the first aircraft to be upgraded, along with spare parts and other services. Air Force personnel will install the hardware at the Tinker AFB, Okla. This installation is scheduled for completion in the third quarter of 2011, according to the company.

E-3 Sentry

A U.S. Air Force E-3 Sentry airborne warning and control system aircraft from the 552nd Air Control Wing heads out to the Nevada Test and Training Range July 24, 2009, during Red Flag 09-4. The U.S. Air Force plans to make a number of long-awaited updates and improvements to the E-3 Sentry. U.S. Air Force photo by Master Sgt. Kevin J. Gruenwald

Four 21,000-pound thrust Pratt & Whitney TF33-PW-100/100A turbofan engines provide power for the AWACS platform, which is an extensively modified Boeing 707-320B fitted with mission avionics that provide all-weather air surveillance and command, control, communications and intelligence for tactical and air defense forces.

On a typical mission, an E-3, which has an unrefueled endurance of 11 hours, routinely refuels and stays aloft for up to 18 hours, carrying a crew of 20, consisting of pilot (aircraft commander), co-pilots, navigator, flight engineer, and 16 AWACS mission specialists. The rear-cabin crew’s mission crew commander oversees weapon controllers, radar operators, and communications specialists. The AWACS aircraft protects itself by detecting aerial threats and vectoring fighters while remaining some distance away.

The heart of the AWACS system is its Westinghouse AN/APY-2 (upgraded from AN/APY-1) Overland Downlook Radar (ODR), which, with other sensors and instrumentation, is housed in a saucer-like rotodome mounted on two 11-foot struts above the rear fuselage. The deep circular rotodome is some 30 feet in diameter, weighs 3,395 pounds and is canted 2.5 degrees downward. In operation, the dome rotates six times per minute.

The radar that relies on this disc-like dome is, itself, housed in the fuselage aft of the wing, below and above the floor. Radar signals and received echoes travel up or down the two rotodome struts. The main radar antenna is a roughly oval beam about 26 feet long and 4.5 feet high. The radar is capable of tracking up to 600 low-flying aircraft.

The new block 40 (for E-3Bs) and 45 (for E-3Cs) upgrade “replaces a mission computer system originally installed in the 1970s,” said Maj. Brett Johnson, AWACS production chief at Tinker, in an Air Force press release. “The new system will have an open, network-based architecture, enabling future net-centric modifications.”

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Robert F. Dorr is an author, U.S. Air Force veteran, and retired American diplomat who...