EA-6B Prowler

The Northrop Grumman (formerly Grumman) EA-6B Prowler is a twin-engine, four-seat, mid-wing electronic-warfare aircraft derived from the A-6 Intruder airframe. The EA-6A was the initial electronic warfare version of the A-6 used by the United States Marine Corps and United States Navy. Development on the more advanced EA-6B began in 1966. An EA-6B aircrew consisted of one pilot and three Electronic Countermeasures Officers, though it was not uncommon for only two ECMOs to be used on missions. It was capable of carrying and firing anti-radiation missiles (ARMs), such as the AGM-88 HARM.

The Prowler was in service with the U.S. Armed Forces from 1971 until 2019. It has carried out numerous missions for jamming enemy radar systems, and in gathering radio intelligence on those and other enemy air defense systems. From the 1998 retirement of the United States Air Force EF-111 Raven electronic warfare aircraft, the EA-6B was the only dedicated electronic warfare plane available for missions by the U.S. Navy, the U.S. Marine Corps, and the U.S. Air Force until the fielding of the Navy's EA-18G Growler in 2009. Following its last deployment in late 2014, the EA-6B was withdrawn from U.S. Navy service in June 2015, followed by the USMC in March 2019.

Development

Origins

The EA-6A "Electric Intruder" was developed for the U.S. Marine Corps during the 1960s to replace its EF-10B Skyknights. The EA-6A was a direct conversion of the standard A-6 Intruder airframe, with two seats, equipped with electronic warfare (EW) equipment. The EA-6A was used by three Marine Corps squadrons during the Vietnam War. A total of 27 EA-6As were produced, 15 of which were newly manufactured. Most of these EA-6As were retired from service in the 1970s with the last few being used by the Navy with two electronic attack "aggressor" squadrons, with all examples finally retired in the 1990s. The EA-6A was essentially an interim warplane until the more-advanced EA-6B could be designed and built.

The substantially redesigned and more advanced EA-6B was developed beginning in 1966 as a replacement for EKA-3B Skywarriors for the U.S. Navy. The forward fuselage was lengthened to create a rear area for a larger four-seat cockpit, and an antenna fairing was added to the tip of its vertical stabilizer. Grumman was awarded a $12.7 million contract to develop an EA-6B prototype on 14 November 1966. The Prowler first flew on 25 May 1968, and it entered service on aircraft carriers in July 1971. Three prototype EA-6Bs were converted from A-6As, and five EA-6Bs were developmental airplanes. A total of 170 EA-6B production aircraft were manufactured from 1966 through 1991.

The EA-6B Prowler was powered by two Pratt & Whitney J52 turbojet engines, and it was capable of high subsonic speeds. Due to its extensive electronic warfare operations, and the aircraft's age (produced until 1991), the EA-6B was a high-maintenance aircraft, and had undergone many frequent equipment upgrades. Although designed as an electronic warfare and command-and-control aircraft for air strike missions, the EA-6B was also capable of attacking some surface targets on its own, in particular enemy radar sites and surface-to-air missile launchers. In addition, the EA-6B was capable of gathering electronic signals intelligence.

The EA-6B Prowler was continually upgraded over the years. The first such upgrade was named "expanded capability" (EXCAP) beginning in 1973. Then came "improved capability" (ICAP) in 1976 and ICAP II in 1980. The ICAP II upgrade provided the EA-6B with the capability of firing Shrike missiles and AGM-88 HARM missiles.

Advanced Capability EA-6B

The ''Advanced Capability EA-6B Prowler (ADVCAP)'' was a development program initiated to improve the flying qualities of the EA-6B and to upgrade the avionics and electronic warfare systems. The intention was to modify all EA-6Bs into the ADVCAP configuration, however the program was removed from the Fiscal Year 1995 budget due to financial pressure from competing Department of Defense acquisition programs.

The ADVCAP development program was initiated in the late 1980s and was broken into three distinct phases: Full-Scale Development (FSD), Vehicle Enhancement Program (VEP) and the Avionics Improvement Program (AIP).

FSD served primarily to evaluate the new AN/ALQ-149 Electronic Warfare System. The program utilized a slightly modified EA-6B to house the new system.

The VEP added numerous changes to the aircraft to address deficiencies with the original EA-6B flying qualities, particularly lateral-directional problems that hampered recovery from out-of-control flight. Bureau Number 158542 was used. Changes included:
* Leading edge strakes (to improve directional stability)
* Fin pod extension (to improve directional stability)
* Ailerons (to improve slow speed lateral control)
* Re-contoured leading edge slats and trailing edge flaps (to compensate for an increase in gross weight)
* Two additional wing stations on the outer wing panel (for jamming pods only)
* New J52-P-409 engines (increased thrust by 2,000 lbf (8.9 kN) per engine)
* New digital Standard Automatic Flight Control System (SAFCS)

The added modifications increased the aircraft gross weight approximately and shifted the center of gravity 3% MAC aft of the baseline EA-6B. In previous models, when operating at sustained high angles of attack, fuel migration would cause additional shifts in CG with the result that the aircraft had slightly negative longitudinal static stability. Results of flight tests of the new configuration showed greatly improved flying qualities and the rearward shift of the CG had minimal impact.

The AIP prototype (bureau number 158547) represented the final ADVCAP configuration, incorporating all of the FSD and VEP modifications plus a completely new avionics suite which added multi-function displays to all crew positions, a head-up display for the pilot, and dual Global Positioning/Inertial navigation systems. The initial joint test phase between the contractor and the US Navy test pilots completed successfully with few deficiencies.

After the program was canceled, the three experimental Prowlers, BuNo 156482, 158542 and 158547, were mothballed until 1999. Over the next several years, the three aircraft were dismantled and reassembled to create a single aircraft, b/n 158542, which the Navy dubbed "FrankenProwler". It was returned to active service on 23 March 2005.

Improved Capability (ICAP) III

Northrop Grumman received contracts from the U.S. Navy to deliver new electronic countermeasures gear to Prowler squadrons; the heart of each ICAP III set consists of the ALQ-218 receiver and new software that provides more precise selective-reactive radar jamming and deception and threat location. The ICAP III sets also are equipped with the Multifunction Information Distribution System (MIDS), which includes the Link 16 data link system. Northrop delivered two lots and delivered two more beginning in 2010. The EA-6B Prowlers in service toward the end of its life were the ICAP III version, carrying the ALQ-99 Tactical Jamming System.

Design

Designed for carrier-based and advanced base operations, the EA-6B was a fully integrated electronic warfare system combining long-range, all-weather capabilities with advanced electronic countermeasures. A forward equipment bay and pod-shaped fairing on the vertical fin housed the additional avionics equipment. It was the primary electronic warfare aircraft for the U.S Navy and U.S. Marine Corps. The EA-6B's primary mission was to support ground-attack strikes by disrupting enemy electromagnetic activity. As a secondary mission it could also gather tactical electronic intelligence within a combat zone, and another secondary mission was attacking enemy radar sites with anti-radiation missiles.

The Prowler had a crew of four, a pilot and three Electronic Countermeasures Officers (known as ECMOs). Powered by two non-afterburning Pratt & Whitney J52-P-408A turbojet engines, it was capable of speeds of up to with a range of 1,140 miles (1,840 km).

Design particulars included the refueling probe being asymmetrical, appearing bent to the right to improve pilot visibility over that of the A-6 Intruder. It contained an antenna near its root. The canopy had a shading of gold to protect the crew against the radio emissions that the electronic warfare equipment produces.

Operational history

The EA-6B entered service with Fleet Replacement Squadron VAQ-129 in September 1970, and Tactical Electronic Warfare Squadron 132 (VAQ-132) became the first operational squadron, in July 1971. This squadron began its first combat deployment to Vietnam on 11 months later, soon followed by VAQ-131 on and VAQ-134 on . Two squadrons of EA-6B Prowlers flew 720 sorties during the Vietnam War in support of US Navy attack aircraft and USAF B-52 bombers.

During the 1983 invasion of Grenada, four Prowlers supported the operation from .

Following the Achille Lauro hijacking, on 10 October 1985 Prowlers from provided ESM support during the interception of the EgyptAir 737 carrying four of the hijackers.

Prowlers jammed Libyan radar during Operation El Dorado Canyon in April 1986. Prowlers from VAQ-135 on jammed Iranian Ground Control Intercept radars, surface-to-air missile guidance radars and communication systems during Operation Praying Mantis on 18 April 1988.

A total of 39 EA-6B Prowlers were involved in Operation Desert Storm in 1991, 27 from six aircraft carriers and 12 from USMC bases. During 4,600 flight hours, Prowlers fired over 150 HARM missiles. Navy Prowlers flew 1,132 sorties and USMC flew 516 with no losses.

With the retirement of the EF-111 Raven in 1998, the EA-6B was the only dedicated aerial radar jammer aircraft of the U.S. Armed Forces, until the fielding of the Navy's EA-18G Growler in 2009. The EA-6B was flown in almost all American combat operations from 1972 until its retirement in 2019, and was frequently flown in support of the U.S. Air Force missions.

In 2001, 124 Prowlers remained, divided between twelve Navy, four Marine, and four joint Navy-Air Force "Expeditionary" squadrons. A Joint Chiefs of Staff (JCS) staff study recommended that the EF-111 Raven be retired to reduce the types of aircraft dedicated to the same mission, which led to an Office of the Secretary of Defense (OSD) program memorandum to establish 4 land based "expeditionary" Prowler squadrons to meet the needs of the Air Force. From 2004-2014 the U.S. Air Force augmented Navy Prowler units with Electronic Warfare Officers from the 388th and 390th Electronic Combat Squadrons assigned to the 366th Operations Group at Mountain Home AFB