The EA-6B was a more advanced electronic warfare version of the A-6. Despite the fact that it used the same wing and fuselage configuration as the A-6 Intruder, it was in fact virtually a completely different aircraft. Consequently, it was given a new name--Prowler.
Despite its designation, the EA-6B was not a conversion of the A-6B, which was a defense suppression attack aircraft. Instead, the EA-6B Prowler was a four-seat electronic warfare aircraft designed to jam and deceive enemy radar and communications facilities. In later versions, it had the ability to fire HARM missiles against radar sites.
Grumman was working on a more advanced version of its EA-6A aircraft when the Navy issued the company a contract for the development of an advanced electronic warfare aircraft in 1964. The EA-6B was to be built up around the AN/ALQ-99 Tactical Jamming System (TJS) that was then under development by the Airborne Instruments Laboratory division of Cutler Hammer. The AN/ALQ-99 system consisted of a series of receivers mounted behind radomes situated inside a large canoe-shaped fairing on top of the vertical stabilizer that could monitor for threats in four specific frequency bands. Additional receivers were installed in blisters lower down on the fin. The data from these receivers was fed into a central mission computer to determine the signal characteristics and to identify their source. The information was then displayed on cockpit displays, and the crew could determine how to jam the emitters. The jammers were carried in individual pods underneath the wings and the fuselage centerline.
The crew was increased to four--a pilot and three electronics countermeasures officers. The pilot sat in front on the left. The TJS operator sat in the right forward seat and doubled as the navigator and as communication operator. The right rear seat position also operated the TJS, while the left rear cockpit position was responsible for operating the communications jamming using the AN/ALQ-92. The communications jammer operator sat in the right rear seat, and the left rear seat was occupied by another TJS operator. In order to accommodated the extra two seats, the basic Intruder fuselage was lengthened by 4 feet 6 inches. The four crew members sit on Martin-Baker GRUEA-7 ejection seats. Entrance to the plane was via a series of steps which hinged down from the intake wall.
An AN/APQ-129 search radar antenna was installed in the extreme nose and an AN/APN-153 Doppler navigation radar was provided. The AN/ALQ-100 defensive ECM set could also be carried.
The wings and the undercarriage were strengthened to accommodate the extra weight. The wingtip dive brakes of the earlier Intruder were retained, as was the midair refuelling probe. The wing root leading edge was swept at a greater angle and was equipped with stall warning strips. Additional fuel capacity was also provided.
The first three EA-6Bs were created by modifying three A-6As (BuNos 149481, 149479, and 148615). 149481 was the flying demonstrator (designated Model 128J by the company) and was first flown on May 25, 1968. 149479 was used for flight testing of the electronic equipment, and 148615 was used as a non-flying test article. Trials were carried out in 1970, and the aircraft carried out a series of carrier qualification tests aboard the USS Midway.
The first production EA-6B (BuNo 158029) flew for the first time in November of 1970. Production of new-build EA-6B aircraft began in January of 1971. Starting with the 22nd EA-6B (BuNo 158544), the 9300 lb.s.t. J52-P-8As were replaced by 11,200 lb.s.t. J52P-408 turbojets. P-408 engines were later retrofitted into all but the first five EA-6Bs.
The first EA-6Bs were delivered to VAQ-132 in July of 1971. The squadron flew ECM support for aircraft carriers in the Gulf of Tonkin and the unit entered combat for the first time in July 1972 with VAQ-131 aboard the USS Enterprise. Two Prowler squadrons were active during the Vietnam conflict, and they carried out 720 combat sorties over North Vietnam. No Prowlers were lost in combat during this time.
Starting with the 29th Prowler, 25 EA-6Bs were delivered in the EXCAP configuration. The EXCAP (Expanded Capability) Prowlers were fitted with the AN/ALQ-99A set, which doubled the frequency coverage. Rather than four, a maximum of 8 frequency bands could now be covered. In service, these sets were upgraded to ALQ-99B and ALQ-99C configurations to improve the reliability. The computer memory was increased in the AN/AYA-6 computer, and a AN/ASH-30 Tactical Electronic Reconnaissance Processing and Evaluation System (TERPES) was added, which provided the aircraft with an electronic intelligence capability. In addition, a digital recording system was provided which made it possible to do post-flight threat analysis. An Exciter Jammer Control Unit was added to provide the TJS with as many as five different jamming modes. The first EXCAP EA-6B was delivered in January 1973. In mid-1982, most of the EXCAP Prowlers were upgraded to ICAP II standards.
The ICAP (Improved Capability) configuration was introduced with the 54th production Prowler. Experience had shown that crew coordination between the two TJS operators was difficult and severely overtaxed the crew member in the right front seat, who was also responsible for navigation and communication. In the ICAP configuration, there was a redistribution of the work among the three electronics countermeasures operators so that the tasks were more equally shared among them. The communication jamming function was relocated to the navigator's position, which was up front beside the pilot. The radar and other jamming functions were relocated to the two rear crew positions. The electronics response time was improved by digitally tuning the surveillance receivers. The AN/APS-130 search radar replaced the AN/APQ-129 set. New chaff dispensing pods were carried. An AN/ALQ-126A self-protection countermeasures set replaced the AN/ALQ-100. The AN/ALQ-126A had a set of receiver antennae located in the sawtooth at the leading edge of the refuelling probe and in a "beer can" extension at the rear of the fin cap equipment pod. The AN/ALQ-100 had been little used because it interfered with the TJS and was in addition rather unreliable. However, the AN/ALQ-126 system did very little to end the problem, so it was little utilized as well, the crew relying primarily on chaff and flares as defensive countermeasures. The new cockpit featured a digital display group, and the AN/APS-130 replaced the AN/APQ-129 search radar. New radios were added, and the AN/ALQ-92 communications jamming system was replaced by an interim AN/ALQ-191. The AN/ALQ-92 was seldom installed in the EA-6B and the operator sitting in the right front seat generally served primarily as a navigator. Even the AN/ALQ-191 system was not installed in every EA-6B. 45 production aircraft were delivered in the ICAP format, the first one flying in July of 1975. Deliveries began in July of 1976. In addition, 21 earlier production aircraft were upgraded to ICAP format.
The ICAP II was a further improvement to the Prowler. The last pre-production Prowler (BuNo 156482) served as the developmental aircraft for the ICAP II and flew for the first time on June 24, 1980. The ICAP II produced some major improvements to the external pods. The TJS was upgraded to the AN/ALQ-99D configuration to cover a wider frequency range. The AN/ASQ-113 jamming system replaced the AN/ASQ-191. In earlier Prowlers, the jamming pods each generated signals within one frequency band and were not capable of being reconfigured in flight, but in ICAP II the pods could generate signals in any one of seven frequency bands, and each pod could jam in two different frequency bands simultaneously. The more advanced AN/AYK-14 computer replaced the earlier AYA-6. The AN/ASN-130 Carrier Inertial Navigation System (CAINS) was installed. There were improved displays for the crew members. Threat information was pre-programmed and automatically entered into an on-board computer. Also added was the ability for two Prowlers to link together via a TACAN datalink to work together in a coordinated electronic warfare mission. The ability to carry and launch the HARM antiradiation missile was incorporated with the 111th production article, and was retrofitted to earlier aircraft. The weapon's control panel was located at the right front navigator's position. Deliveries of the ICAP II Prowler began with the 99th production machine in January of 1984. All surviving ICAP I and ICAP Mod 1 aircraft were brought up to ICAP II standards.
Beginning with P-134 (BuNo 163049), ICAP II planes were completed to "Block 86" standards, the 86 indicative of the fiscal year in which they were ordered. Earlier ICAP IIs were retroactively known as Block 82s. Changes included dual AN/ARC-182 UHF/VHF radios. "Block 86" planes can be identified by the presence of three new antennae on the dorsal spine of the fuselage and under the nose. Between 1983 and 1991, Grumman modified 15 EXCAP and 57 ICAP I Prowlers to ICAP II standards.
Prowler production came to an end with the delivery of the 170th example, BuNo 164403. It was delivered on July 29, 1991. All of the subsequent changes to the Prowler were by upgrades to existing aircraft.
The next series of Prowler upgrades were to be known as ADVCAP (Advanced Capability). The ADVCAP would have introduced new jammer transmission and detection capabilities, along with an expansion of the AN/ALE-39 chaff dispenser set. The ADVCAP also would have incorporated the AN/ALQ-165 Airborne Self-Protection Jammer (ASPJ) an AN/ALQ-149 communications jamming system, and AN/ALR-67 radar warning receiver. ADVCAP Prowlers also would have Global Positioning System for navigation. Two additional wing stations would be added. A disk-based recorder/onboard program loader unit was to replace the former tape-based system. The weight of the additional equipment required the replacement of the engines with the more powerful 12,000 lb.s.t. J52-P-409. Also included in the AVCAP program were a series of airframe modifications known as the Vehicle Enhancement Program (VEP). Under the VEP, strakes were to be added along the junction of the wing's leading edge with the cockpit and new flaps and slats were to be provided. In addition, speed brakes were to be modified and extension was to be made to the vertical stabilizer. These structural modifications were made to P-20 (BuNo 158542). Aircraft (BuNo 156482) flew for the first time with the receiver processing group installed on October 29, 1990. However, funding for the ADVCAP program was not included in the FY95 Navy budget and the program was subsequently cancelled.
Despite the cancellation of the ADVCAP program, the Navy still needed upgrades for its Prowler fleet. The next phase was known as "Block 89A", and included an upgrade of 69 Block 82 and 56 Block 89 aircraft. This standard gives the aircraft a common avionics package that included an AN/AYK-14 computer, AN/ARC-210 radios, GPS, a new instrument landing system, and commercially-available EFIS. Part of the upgrade would involve improve high band and low-band jamming pods, scheduled to reach IOC in 2003. Upgraded universal exciters along with the AN/ASQ-113 communications jammer were also to be included. The first of four upgraded Block 89A EA-6Bs flew at Northrop Grumman's St. Augustine, Florida facility on June 8, 1997. It is intended that the entire EA-6B fleet will be upgraded to Block 89A standards before the ICAP III modifications are made.
The ICAP III program will bring the EA-6B fleet additional updated equipment to include new electronic support measures capable of more rapidly and more precisely determining the characteristics of hostile radar emissions. A new Litton LR-700 system will be developed that will be capable of precisely pinpointing the location of enemy radar sites and will allow the Prowler crews to make more effective use of their HARM missiles. A GPS-imbedded inertial reference system will allow crews to employ jamming assets against the most dangerous threats. The program will also integrate the Lockheed Martin/Sanders AN/ASQ-113 into the AN?ALW-99 TJS via the multifunction information distribution system. A new controls and display suite that includes the multimission advanced tactical terminal will be installed in the rear cockpit, which will provide a reactive jamming capability against frequency-agile radars and will provide rapid geolocation of hostile emitters for attack by HARM missiles. Two Block 89A EA-6Bs will be modified as test aircraft.
Engines: Two Pratt & Whitney J52-P-408 non-afterburning turbojets, 11,200 lb.s.t. each. Performance: Maximum speed 658 mph at sea level. Cruising speed 482 mph. Stalling speed 133 mph. Service ceiling 41,400 feet. Initial climb rate 8600 feet/min. Normal range 1628 miles. Maximum ferry range 2021 miles. Weights: 32,160 pounds empty, 48,300 pounds loaded, 65,000 pounds maximum. Dimensions: Wingspan 53 feet 0 inches, length 59 feet 9.8 inches, height 16 feet 3 inches, wing area 529 square feet. Armament: No cannon armament. A maximum weapons load of 15,000 pounds could be carried on four underwing hardpoints and one centerline hardpoint.
156478/156482 Grumman EA-6B Prowler c/n P-1/5. 156604/156607 Grumman EA-6B Prowler contract cancelled 157977/157979 Grumman EA-6B Prowler cancelled contract 158029/158040 Grumman EA-6B-30-GR Prowler c/n MP-6/17. 158540/158547 Grumman EA-6B-35-GR Prowler c/n MP-18/25 158649/158651 Grumman EA-6B-40-GR Prowler c/n MP-26/28. 158799/158817 Grumman EA-6B-45-GR Prowler c/n MP-29/47 159582/159587 Grumman EA-6B EXCAP Prowler c/n MP-48/53 159907/159912 Grumman EA-6B ICAP I Prowler c/n MP-54/59 160432/160437 Grumman EA-6B ICAP I Prowler c/n MP-60/65 160609 Grumman EA-6B ICAP I Prowler c/n MP-66 160704/160709 Grumman EA-6B ICAP I Prowler c/n MP-67/72 160786/160791 Grumman EA-6B ICAP I Prowler c/n MP-73/78 161115/161120 Grumman EA-6B ICAP I Prowler c/n MP-79/84 161242/161247 Grumman EA-6B ICAP I Prowler c/n MP-85/90 161347/161352 Grumman EA-6B ICAP I Prowler c/n MP-91/96 161774/161775 Grumman EA-6B ICAP I Prowler c/n MP-97/98 161776/161779 Grumman EA-6B ICAP II Prowler c/n MP-99/102 161880/161885 Grumman EA-6B ICAP II Prowler c/n MP-103/108 161886/161897 Grumman A-6E Intruder contract cancelled. 162223/162246 Grumman EA-6B ICAP II Block 82 Prowler 162223/162230 c/n MP-109/116 162231/162246 cancelled. 162934/162941 Grumman EA-6B ICAP II Block 82 Prowler c/n P-117/122 162940 and 162941 cancelled 163030/163035 Grumman EA-6B ICAP II Block 82 Prowler c/n MP-123/128. 163044/163048 Grumman EA-6B ICAP II Block 82 Prowler c/n MP-129/133 163049 Grumman EA-6B ICAP II Block 86 Prowler c/n P-134 163395/163406 Grumman EA-6B ICAP II Block 86 Prowler c/n MP-135/146 163520/163531 Grumman EA-6B ICAP II Block 86 Prowler c/n MP-147/158 163884/163892 Grumman EA-6B ICAP II Block 86 Prowler c/n MP-159/167. 164182/164193 Grumman EA-6B contract cancelled 164401/164402 Grumman EA-6B ICAP II Block 86 Prowler c/n MP-168/169. 164403 Grumman EA-6B ICAP II Block 89 Prowler c/n MP-170