In the late 1960s and early 1970s, the Air Force was shopping around for possible replacements for its Douglas EB-66 electronic warfare aircraft. Although the EB-66 still continued to fly combat missions over North Vietnam, it was rapidly beginning to show signs of age.
The Air Force rejected the development of a completely new type of aircraft for this role as being economically impractical because of the small number of aircraft required. At one time, some thought had been given to acquiring the Grumman EA-6B Prowler carrier-based electronic warfare aircraft, but the Air Force was reluctant to acquire yet another aircraft originally developed for the Navy. After some thought, the Air Force concluded in 1972 that the modification of some existing F-111A strike fighters would be the most cost-effective solution.
However, the EA-6B was a four-seat aircraft, and it was concluded that it was impractical to adapt the F-111A to a four-seat configuration because it would reduce internal capacity too much. The only alternative was to develop equipment similar to the Tactical Jamming System of the EA-6B, but capable of being operated by a single electronics warfare officer.
In December 1974, the Grumman Aircraft Corporation of Calverton, Long Island was selected as the prime contractor for this conversion. On January 30, 1975, Grumman was awarded a contract for the modification of two F-111As (serials 66-0041 and 66-0049) as EF-111A prototypes, the E prefix standing for "Electronic".
The modifications included the installation of an AN/ALQ-99E jamming subsystem. Exciters, antennae, and other items were mounted on a pallet inside the internal weapons bay. Other components were mounted inside a 16-foot ventral "canoe"-shaped radome. A fin-tip pod accommodated the electronic countermeasures receivers. The self-protection subsystem consisted of a jamming system and a countermeasures dispensing set. A terminal threat warning subsystem was installed which consisted of infrared and electronic countermeasures receiver sets. The vertical fin had to be reinforced in order to support the fin-tip pod, new electrical wiring had to be installed, 60 kVA generators were replaced by 90 kVA units, and an improved environmental system for electronic equipment cooling was fitted. The cockpit had to be rearranged to accommodate the new electronic warfare officer position, with the flight controls being removed from the right-hand cockpit, the navigation equipment being relocated so that could be used by the pilot in the left-hand seat, and the controls and displays for the electronics warfare officer being installed in the right-hand cockpit.
These modifications resulted in an increase of empty weight from 46,172 pounds for the F-111A to 55,275 pounds for the EF-111A. However, since the EF-111A carried no weapons, its maximum takeoff weight was only 88,848 pounds as compared with 98,850 pounds for the F-111A. The Pratt & Whitney TF30-P-3 turbofans of the F-111A were retained.
Grumman first flew a partially-modified F-111A fitted with a mockup of the ventral canoe in December of 1975. The first EF-111A prototype (serial number 66-0049) flew at Calverton on March 10, 1977. It was complete with fin-tip pod and ventral fairing, but still lacked most of its electronic equipment.
The first flight of a fully-equipped EF-111A (serial number 66-0041) was made on May 17, 1977. This aircraft was delivered to the Air Force to be used by Detachment 3 of the Tactial Air Warfare Center at Mountain Home AFB in Idaho for operational test and evaluation.
Satisfactory results from these tests led to the issuance of a contract for the modification of six more aircraft. Later, 34 more conversions were ordered.
The name *Raven* was officially adopted for the EF-111A.
First deliveries of EF-111A Ravens were made to the 390th Electronic Combat Squadron of the 366th Tactical Fighter Wing at Mountain Home AFB in Idaho in November 1981 and to the 42nd ECS of the 20th TFW at RAF Upper Heyford in February 1984. 42 Ravens had been delivered to the 366th TFW and the 20th TFW by December of 1985. Mountain Home AFB received most of them.
The first operational mission for the Raven took place during Operation Eldorado Canyon, the retaliatory attack on Libya on the night of April 14-15, 1986. During that mission, the 42nd ECS provided three EF-111As plus two spare aircraft to jam the Libyan radar network.
In 1986, General Dynamics was given a contract to install more powerful TF30-P-9 turbofans in the EF-111A.
In May of 1988, a contract for the update of the AN/ALQ-99E by the AIL Division of the Eaton Corporation was cancelled due to cost overruns.
Under an Air Force contract awarded in January 1987, Grumman and TRW Inc. developed the Avionics Modernization Program (AMP) kit for the EF-111A. These kits provided the EF-111A with improved terrain following and navigational radars, a ring laser gyro inertial navigation system, the capability for using the global positioning system, two digital computers, improved cockpit displays, and upgraded communication systems. The first AMP kit was installed in EF-111A 66-0018 in January of 1989. Most existing EF-111As were later to receive this upgrade.
Eighteen EF-111A Ravens were deployed in support of Operation Desert Storm in 1991. They flew over 900 sorties. None were lost in combat, but one was lost in a non-combat related accident and both crew members were killed.
The EF-111A Raven was even credited with a "kill" during Desert Storm. On the night of January 17, 1991, an Iraqi Mirage F.1 flew into the ground while chasing EF-111A serial number 66-0016. Even though the Raven is unarmed and has no air-to-air capability, the Raven crew was given credit for the kill.
The last six EF-111As that had been deployed to Al Kharj Air Base in Saudi Arabia for Operation Southern Watch returned to the USA in April of 1998. This ended the deployment of the EF-111A to the Persian Gulf. The role of the EF-111A will be taken over by Al Kharj-based EA-6Bs flown by mixed Navy and Air Force crews.
In the late 1990s, the EF-111As were all retired from the USAF and sent to AMARC for storage. The USAF retired the final examples of the EF-111A Raven from service with the 429th ECS of the 27th FW at Cannon AFB, New Mexico on May 2, 1998. This marked the end of the line for service of the F-111 with the USAAF, all of the fighter-bomber and strategic bomber versions having been retired several years earlier.
Serials of the EF-111A Raven (all conversions from F-111A blocks): 66-0013/66-0016, 66-0018/66-0021, 66-0023, 66-0027, 66-0028, 66-0030, 66-0031, 66-0033, 66-0035/66-0039, 66-0041, 66-0044, 66-0046/66-0051, 66-0055/66-0057, 67-0032/67-0035, 67-0037/67-0039, 67-0041, 67-0042, 67-0044, 67-0048, 67-0052.
Engines: Two Pratt & Whitney TF30-P-3 turbofans, 10,750 lb.s.t. dry, 18,500 lb.s.t. with afterburning. Maximum speed: 1377 mph at 40,000 feet. Initial climb rate 11,000 feet per minute. Service ceiling 45,000 feet. Normal range 929 miles. Dimensions: wingspan 63 feet 0 inches (maximum), 31 feet 11 1/2 inches (minimum), length 76 feet 0 inches, height 20 feet 0 inches, wing area 525 square feet. Weights: 55,275 pounds empty, 70,000 pounds loaded, 88,948 pounds maximum takeoff.