The General Dynamics/Grumman EF-111A Raven was an electronic warfare aircraft designed to replace the obsolete B-66 Destroyer in the United States Air Force. Its crews and maintainers often called it the "Spark-Vark", a play on the F-111's "Aardvark" then nickname.
In 1972, the USAF contracted Grumman to convert some existing General Dynamics F-111As into electronic warfare/electronic countermeasures (ECM) aircraft. The USAF had considered the Navy Grumman EA-6B Prowler, but was reluctant to adopt a Navy aircraft. After the EF-111 retired in the 1990s, the Air Force began depending on Navy and Marine Corps EA-6B squadrons for electronic warfare.
The Raven retained the F-111A's navigation systems, with a revised AN/APQ-160 radar primarily for ground mapping. The primary feature of the Raven, however, was the Raytheon AN/ALQ-99E jamming system, developed from the Navy's ALQ-99 on the Prowler. Its primary electronics were installed in the weapons bay, with transmitters fitted in a 16 feet (4.9 m) long ventral "canoe" radome; the complete installation weighed some 6,000 pounds (2,700 kg). Receivers were installed in a fin-tip pod, or "football", similar to that of the EA-6B. The aircraft's electrical and cooling systems had to be extensively upgraded to support this equipment. The cockpit was also rearranged, with all flight and navigation displays relocated to the pilot's side, and flight controls except throttles being removed from the other seat, where the electronic warfare officer's instrumentation and controls were installed.
The EF-111 is unarmed. The aircraft's speed and acceleration were its main means of self-defense. The EF-111 was not capable of firing anti-radiation missiles in the lethal SEAD role, which was a tactical limitation. A few sources indicated that the inner wing pylons could be fitted to allow carriage of AIM-9 Sidewinders for self-defense. The EF-111A's engines were upgraded to the more powerful TF30-P-9 of the -D model, with 12,000 pounds-force (53 kN) dry and 19,600 lbf (87 kN) afterburning thrust in 1986.
From 1987 to 1994 the Spark 'Vark underwent an Avionics Modernization Program (AMP), similar to the Pacer Strike program for the F model. This added a dual AN/ASN-41 ring laser gyroscope INS, AN/APN-218 Doppler radar, and an updated AN/APQ-146 terrain-following radar. Cockpit displays were upgraded with multi-function displays borrowed from the F-16 Fighting Falcon.