The General Dynamics–Grumman EF-111A Raven is a retired electronic-warfare aircraft designed to replace the EB-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" nickname. The USAF contracted with Grumman in 1974 to convert some existing General Dynamics F-111As into electronic warfare/electronic countermeasures (ECM) aircraft. The USAF had considered the Navy / Marine Corps Grumman EA-6B Prowler, but desired a penetrating aircraft with supersonic speed. The EF-111 entered service in 1983 and served until its retirement in 1998. Design and development In the late 1960s, the U.S. Air Force sought to replace its aging EB-66 and EB-57 electronic warfare aircraft. The Air Force studied the use of Navy EA-6B Prowlers during 1967–1968. However, the Air Force desired a penetrating electronic jamming aircraft with supersonic speed, and, in 1972, decided to modify F-111As into electronic warfare aircraft as a cost-effective option. In January 1974, the Air Force awarded electronic warfare study contracts to Grumman and General Dynamics. Grumman was selected as the EF-111 prime contractor in December 1974, then was awarded a contract to modify two F-111As into EF-111 prototypes in January 1975. The first fully equipped model, known then as the "Electric Fox", flew on 10 March 1977. A total of 42 airframes were converted at a total cost of US$1.5 billion. The first EF-111s were deployed in November 1981 to the 388th Tactical Electronic Squadron, Mountain Home AFB, Idaho. The last was delivered in 1985. 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 AN/ALQ-99E jamming system, developed from the Navy's ALQ-99 on the Prowler. The aircraft also utilized the ALR-62 Countermeasures Receiving System (CRS) as a Radar Homing and Warning (RHAW) System, the same system carried by all F-111 fighter/bomber models in the United States and Australia. The ALQ-99E primary electronics were installed in the weapons bay, with transmitters fitted in a long ventral "canoe" radome; the complete installation weighed some . 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,