Grumman A-6 Intruder & EA-6B Prowler (2024)

* In the 1950s, the US Navy began work on a new carrier-based attackaircraft, which emerged in the 1960s as the formidable Grumman "A-6Intruder". The Intruder was a prominent participant in the Vietnam War andfollowing US conflicts to the end of the century, operating in both attackand electronic countermeasure (ECM) roles. An optimized ECM derivative, the"EA-6B Prowler", was also an important asset in the post-Vietnam timeframe.This document provides a history and description of the Intruder and Prowler.

[1] A-6 ORIGINS

* In the mid-1950s, the US Navy began consideration of an all-weathertwo-seat jet attack aircraft, issuing a request for proposals (RFP) for suchan aircraft in 1956. The machine would be capable of performing strikemissions ranging from nuclear weapon delivery to battlefield close airsupport (CAS). A short take-off & landing (STOL) capability was preferred,since the Marines were to also obtain the aircraft and might need to operateit off of short airfields; in addition, STOL capability would help theaircraft operate off the smaller ESSEX-class aircraft carriers. All themajor US aircraft manufacturers submitted proposals; after winnowing throughthem, the proposals by Douglas, Grumman, and Vought were selected asfinalists, with Grumman winning the contract to develop the "A2F-1", as itwas then designated, in January 1958.

The Grumman design team, headed by Lawrence M. Mead, had come up with a setof concepts, with their final selection for the "Grumman Model 128" involvinga machine with moderately swept flight surfaces, featuring mid-mounted wingsand a conventional tail arrangement; side-by-side seating for the two crew;and twin Pratt & Whitney (P&W) J52 non-afterburning turbojets, mounted on thefuselage under the wing roots. Given its all-weather mission, it would havean extremely sophisticated avionics suite for the era, with the aircraftbeing designed as a "total weapon system" -- a new concept, in which avionicssystems were designed in from the start and not tacked on later.

As development proceeded, the Navy expressed interest in an electroniccountermeasures (ECM) variant of the A2F-1, which Grumman agreeably drew upas the "A2F-1Q", with development proceeding on the A2F-1 with an eye tomaking sure that it accommodated the ECM configuration down the road. Thecompany also came up with a variant of the A2F-1, the "Model 128B", for theAir Force that provided both reconnaissance and strike capability, but unlikethe ECM development the Air Force concept never happened.

In 1959, the Navy awarded Grumman a contract for construction of eightdevelopment machines, with the first "A2F-1 Intruder", as the type had beennamed, performing its initial flight on 19 April 1960, with test pilot RobertSmyth at the controls. It was not fitted with full combat avionics; neitherwas the second development machine, which performed its first flight on 28 July 1960. Some sources refer to the development machines withthe designation of "YA2F-1", but this is disputed.

Subsequent development machines brought the Intruder up towards productionspec. In 1962, the military acquired a new multiservice designation system,with the A2F-1 becoming the "A-6A" and the A2F-1Q becoming the "EA-6A".By that time, Grumman was already rolling out the first batch of productionA-6As, leading to manufacture of 488 in all, including the developmentmachines, to end of production of the variant in 1970. Initial flight of anEA-6A was in 1963, with initial service deliveries of the A-6A in the sameyear. The US Navy and Marines were the only users of the A-6 family; thetype never served with foreign air arms.

[2] A-6A DESCRIBED / A-6A IN COMBAT

* The A-6A provides a useful baseline for a description of the family. TheA-6A was mostly made of aircraft aluminum alloy and had a tadpole-shapedfuselage, with a broad nose to accommodate the side-by-side co*ckpit and theradar system to then taper back to a slender tail. Field of view throughthe "bugeyed" canopy was outstanding, with aircrew able to see almost straightdown.

The A-6A was powered by twin P&W J52-P-8A turbojets mounted against thefuselage under the wing roots, providing a maximum of 41.4 kN (4,218 kgp /9,300 lbf) thrust each -- the initial prototypes and early production hadbeen powered by J52-P-6A engines with 37.8 kN (3,855 kgp / 8,500 lbf) thrusteach, with operational machines later upgraded to the -8A engines. Themid-mounted wings had a quarter-chord sweep of 52 degrees. The tailplane wasof all-moving configuration.

The engines were fed by simple dee-style intakes, with a small splitter plateagainst the fuselage forward of each intake to prevent an engine fromingesting stagnant "boundary layer" air hugging the surface of the aircraft.The original plan had been to fit the Intruder with exhausts that could pivotdownward to provide better STOL performance. The first four developmentaircraft had the pivoting exhausts, but they weren't very useful, and alllater machines had fixed exhausts, pointed slightly downward to improve lift,and also spare the tail assembly from exhaust blast. Internal fuel capacitywas 8,873 liters (2,344 US gallons), with tanks in the mid-fuselage and inthe wings running out to near the wingtip.

The wing arrangement was somewhat unusual. The overall planform was nothingstrange, a moderately swept wing with a small "leading edge root extension"at the front of the wing root; the wings folded straight up hydraulically atabout a third of the span from the wing root. There was a prominent wingfence on both the inboard and outboard wing sections, intended to preventloss of lift due to airflow diverted down the span of the wing; pictures ofthe development machines suggest that only the inboard wing fence was fittedearly on. The wing was thick at the root and very strong.

The flight control surface arrangement was definitely unconventional, eachwing featuring:

• A leading edge slat running from the wing root extension out to near the wingtip, split at the wingfold.
• A slotted "flaperon" assembly fitted to the rear edge of the wing, running from the root out to near the wingtip, also split at the wingfold. The flaperon was capable of being used as both flap and aileron.
• A spoiler directly forward of the flaperon on top of the wing, again split at the wingfold, that could be used for roll control as well as "lift dumping" for landings.
• Air brakes consisting of panels top and bottom on the trailing edge of the wing near the wingtip. The airbrakes could be used on carrier approach, permitting a slow landing approach while maintaining engine thrust; if the approach was waved off, closing the airbrakes allowed the aircraft to regain speed quickly.

Early on, there was also an airbrake on each side of the rear fuselage, butthey caused pitch problems. Although provisions for the fuselage airbrakeswere retained well into A-6A production, they were disabled in service.Later A-6A production deleted the fuselage airbrakes, and the airbrake recessin earlier production machines was generally faired over. There was nothingparticularly unusual about the aircraft's tail assembly, except for a coolingair inlet in the forward tailfin fillet. All flight surfaces werehydraulically actuated.

The A-6A featured tricycle landing gear, the nose gear being fitted with twinwheels and retracting backward, while each main gear had a single wheel andretracted forward into the inboard section of the wing, the wheel pivoting 90degrees to lie flat. There was a carrier catapult attachment on the nosegear assembly, and a stinger-type arresting hook under the rear fuselage.There was also a peculiar-looking small fitting under the tail that served asa tail bumper and a deck tiedown attachment hookup, with a fuel-dump pipe inits rear.

 ___________________________________________________________________ GRUMMAN A-6A INTRUDER: ___________________________________________________________________ wingspan: 16.15 meters (53 feet) wingspan, folded: 7.67 meters (25 feet 2 inches) wing area: 49.15 sq_meters (529 sq_feet) length: 16.64 meters (54 feet 7 inches) height: 4.75 meters (15 feet 7 inches) empty weight: 11,650 kilograms (25,685 pounds) MTO weight: 27,500 kilograms (60,625 pounds) max speed at altitude: 1,100 KPH (680 MPH / 595 KT) service ceiling: 12,700 meters (41,660 feet) range, full warload: 1,625 kilometers (1,010 MI / 890 NMI) ferry range: 4,410 kilometers (2,740 MI / 2,380 NMI) ___________________________________________________________________

The A-6A had no internal armament. External stores were carried on fiveexternal pylons -- one on the centerline, two under each inner wing section-- all of which were "wet", capable of carrying external tanks. Maximumwarload consisted of six 225-kilogram (500-pound) bombs on each pylon usingmultiple ejector racks (MERs) for a total of 30 bombs, or a hefty load of4,575 kilograms (15,000 pounds). Rockeye and other cluster bombs, navalmines, and even a nuclear store could also be carried. It would have been nogreat trouble to have qualified the Intruder to carry the AIM-9 Sidewinderheat-seeking air-to-air missile (AAM) for self-defense, since all itbasically required was to wire up the missile through a stores pylon to thepilot's headphones, the missile indicating target lock with a tone. However,there's not much evidence that the A-6 ever carried AAMs for self-defense, orwas even qualified for them.

In operational practice, missions seem to have generally involved a singleexternal tank on the centerline pylon, or two tanks on underwing pylons,along with munitions. A fixed probe for probe-&-drogue refueling was fittedin front of the co*ckpit; sources hint that not all aircraft had the probe,but it's hard to find any pictures of an A-6A without one except for thefirst prototype.

The A-6A had a highly sophisticated avionics package for its era, focused onthe "Digital Integrated Attack Navigation Equipment (DIANE)" system, whichwas built around a Norden AN/APQ-92 search radar coupled to a Naval AvionicsFacility (NAF) AN/APQ-88 track radar -- quickly replaced in production by theimproved NAF AN/APQ-112 -- in the bulbous nose radome. DIANE also includedan inertial navigation system, an air data computer, a ballistics computer,and a Doppler navigation radar. Other aircraft avionics included radios,identification friend or foe (IFF) transponder, an automatic direction finderfor homing in on navigation beacons, and a TACAN air navigation signalreceiver. A radar warning receiver (RWR) was fitted, reflected by a fairingin the back of the tailfin directly above the rudder; pictures of earlyprototypes don't show the RWR, and it may have been fitted some time afterproduction began.

The pilot and the bombardier-navigator (B/N) sat side by side under a canopythat slid back to open. The B/N's position was offset about a hand's widthto the rear of the pilot's. They sat on Mark-Baker Mark 5 ejection seatsthat could provide safe ejection at any altitude from ground on up, butrequired a minimum speed of 185 KPH (115 MPH / 100 KT). Late productionA-6As were fitted with Martin-Baker Mark 7 ejection seats with true"zero-zero" -- zero speed, zero altitude -- capability; these seats also hadthe ability to recline back to improve crew comfort on long flights. Theaircrew got in using a step that hinged down from the engine nacelle on eachside of the aircraft.

* With war heating in Southeast Asia in the early 1960s, the Intruder quicklysaw action. The A-6A performed its first combat sorties over Vietnam on 1July 1965, with aircraft from the carrier USS INDEPENDENCE pounding targetssouth of Hanoi. There were initial teething problems in combat, oneparticularly ugly one resulting in the loss of three A-6As when their bombsdetonated immediately after release. The problem turned out to be due to thebomb rack arrangement, with the bombs colliding after drop, and was quicklyfixed.

Nobody would have ever described the Intruder as a pretty aircraft, but theA-6A proved a very valuable resource, able to perform accurate strikes innight and bad weather. It proved to be an excellent ride at low level,being compared to a "Cadillac". The only major problem was that the DIANEsystem's reliability was very poor, meaning the aircraft spent a lot of timein the shop, with operational availability rates running from half to a thirdof the Intruder force. In night operations, combat losses were low; theywere substantially higher for the daytime battlefield close-support role,which was better served by the old Douglas A-1 Skyraider piston aircraft inany case.

Another difficulty with the sophistication of the A-6A was that it presenteda steep learning curve to the B/N. For most of the early years, the B/Ns gottheir early flight training on Douglas TA-3B Skywarrior aircraft, but theTA-3B's radar system was not comparable to that of the A-6A and so thetraining on the TA-3B was of limited usefulness. Recognizing the problem,the Navy put in motion an effort to acquire a specialized systems trainer forthe A-6A, slapping the A-6A nose and its major combat avionics systems onto aGulfstream I twin-turboprop executive aircraft. The first "TC-4C Academe",as the result was named, performed its initial flight in 1967, with nineAcademes built in all.

The A-6A served throughout the Vietnam conflict. Normal colors were typicalUS Navy light gray on top and white on the bottom, though some wereexperimentally painted dark green on top for a time. In 1966, an updateprogram was put into motion to update the A-6A's AN/APQ-92 and AN/APQ-112radar systems, as well as fit a more durable and effective nose radome.

By the time the Americans effectively withdrew from Vietnam in 1972, the Navyand Marines had lost 67 A-6As in combat and 11 in accidents. The A-6A assuch didn't long survive the war, the fleet being used as a "feedstock" forconversion into other Intruder variants, as discussed below, with theconversion process begun well before the end of the war.

[3] EA-6A / A-6B / A-6C / KA-6D

* Development of the EA-6A ECM aircraft followed that of the A-6A, with twoearly production A-6As converted to EA-6A prototypes, the first performing itsinitial flight on 26 April 1963. The "Electric Intruder", as it was formallyknown, looked very much like the A-6A, the only clear visible differencebeing a prominent "football" fairing on the top of the tailfin for theAN/ALQ-85 signal surveillance / receiver system. The wingtip airbrakes werealso deleted in order to mount hoop antennas under the wingtips; the EA-6Aretained functional fuselage airbrakes. The forward fuselage was stretchedby about 20 centimeters (8 inches) to allow fit of the ECM gear.

The EA-6A could carry radio frequency (RF) jammer pods, chaff pods, or fueltanks on its underwing pylons -- an extra pylon was fitted outside the wingfold, capable of hauling light stores like chaff dispensers, giving a totalof seven pylons. In principle, it could also carry offensive stores, it hada rudimentary attack system, but it rarely if ever did so in practice. TheECM systems were operated by an "electronics countermeasures officer (ECMO)"-- a job description historically known as a "crow" or "raven" for someobscure reason -- who doubled as navigator.

 ___________________________________________________________________ GRUMMAN EA-6A ELECTRIC INTRUDER: ___________________________________________________________________ wingspan: 16.15 meters (53 feet) wingspan, folded: 7.67 meters (25 feet 2 inches) wing area: 49.15 sq_meters (529 sq_feet) length: 16.64 meters (54 feet 7 inches) height: 4.95 meters (16 feet 3 inches) empty weight: 12,595 kilograms (27,770 pounds) MTO weight: 25,630 kilograms (56,500 pounds) max speed at altitude: 1,000 KPH (620 MPH / 540 KT) service ceiling: 12,700 meters (41,660 feet) range, full warload: 1,625 kilometers (1,010 MI / 890 NMI) ferry range: 4,100 kilometers (2,545 MI / 2,215 NMI) ___________________________________________________________________

Not counting the two prototypes, a total of 25 EA-6As was built, including 10rebuilds of A-6As and 15 new-production machines, the first being deliveredto the Marines in 1965 and the last being rolled out in 1969. They replacedthe elderly and antiquated Douglas EF-10B Skyknight in combat, providing ECMto protect strike packages. They typically flew with two drop tanks, threejammer pods, and two chaff dispenser pods. The EA-6As only saw combat inVietnam with the Marines. At least two EA-6As were lost in Vietnam, onedisappearing on an operational sortie along with its crew; the other beingdestroyed in an accident, with the crew ejecting safely.

After the conflict, the EA-6As remained in service with both the Marines andNavy, it seems increasingly in the "electronic aggressor" role, used tobaffle the electronic systems of participants in military training exercises.The EA-6As were given sets of upgrades to keep them useful.

* The EA-6A was an ECM platform, intended to blind and confuse adversarydefenses. There was another approach for dealing with adversary defenses,namely to destroy them, with that mission given the melodramatic name of"Iron Hand", though later it would be given the blander designation of"suppression of enemy air defenses (SEAD)". As the war dragged on inSoutheast Asia, the Navy became increasingly fond of the idea of taking onanti-aircraft defense sites, and so a program was set up to covert A-6As intospecialized SEAD aircraft, to be designated "A-6B".

A total of 19 conversions was performed from 1967 into 1970. The A-6Bs werestripped of the primary attack kit of the A-6A and fitted with what wasgenerally known at the time as a "radar homing and warning system (RHAWS)"designed to locate and characterize radars from air-defense sites. Once theradars were targeted, the A-6B would then take them out using its load of"anti-radar missiles (ARMs)", with the aircraft usually carrying two AGM-45Shrike ARMs -- a derivative of the AIM-7 Sparrow AAM -- and two AGM-78Standard ARMs AKA STARMs -- a much bigger and more capable weapon, amodification of the shipboard Standard surface-to-air missile (SAM). Withthe radars out, other strike aircraft would plaster the air-defense site withhigh-explosive and cluster bombs.

After delivery of the first ten A-6Bs, three were built using an improvedRHAWS, the "Passive Angle Tracking ARM (PAT/ARM)" system developed by theApplied Physics Laboratory of the Johns Hopkins University, with the PAT/ARMproviding better support for the AGM-78 STARM. The last six A-6Bs werefitted with the further improved IBM "Target Identification AcquisitionSystem (TIAS)". At least some of the versions of the A-6B had an antennaprotruding from the wing leading edge directly over each outer stores pylon,providing a recognition feature, though it is unclear if this arrangement wascommon to all three A-6B subvariants. The SEAD mission was necessarilydangerous since it involved looking for trouble instead of avoiding it, andfive A-6Bs were lost in combat.

* A batch of A-6As was modified to a highly specialized configuration toperform night attacks on truck convoys moving down the Ho Chi Minh trailthrough Laos and Cambodia, with this variant being designated the "A-6C". Itwas related to a program named "Trails Roads Interdiction Multisensor (TRIM)"program, in which Lockheed Neptune ocean patrol aircraft were fitted with asensor package to similarly perform attacks on the trail. The TRIM systemincluded a forward-looking infrared (FLIR) camera, a low light leveltelevision (LLTV) camera, and a "Black Crow" system that could in principlezero in on the radio emissions of the ignition system of truck engines.

An A-6A was modified as a prototype, the "NA-6A", featuring the sensorscarried in underwing pods, this machine performing its initial flights inlate 1968. A dozen A-6As were converted to the A-6C configuration during1970, with these machines including the sensor package in a reasonably neatfairing under the rear of the belly. Not much is known about the career ofthe A-6Cs, though apparently the sensors were "draggy" and seriouslycut into performance. Much of the high tech used in the Vietnam War wasleading-edge and unreliable; it might be guessed the A-6Cs spent a fairamount of time in the shop. One A-6C was lost in combat. It appears theexercise was not regarded as a success.

* The Navy had tinkered early on with using the A-6A as an inflight refuelingtanker, carrying a "buddy tanking" pod on a stores pylon, but at the time itwasn't seen as a particular good platform for the task -- it could carry alarge fuel load, but it was relatively expensive to operate, and the A-6Awas needed for the strike role. Other platforms could do the tanker job.

In 1968, however, the Navy reconsidered use of the Intruder as a tanker.There were plenty of A-6As in service, and it made sense to spare some ofthem as tankers. The first "KA-6D" tanker performed its initial flight on 16April 1970, leading to a total of 90 conversions, all of the machines havingstarted life as A-6As -- though a dozen of these A-6As had been previouslyconverted to A-6Es, see below. The conversions involved extensivereconditioning, and refit with new wiring; most of the complicated attackavionics were removed, though in principle the KA-6D was still capable ofperforming daylight strikes. It never did.

The KA-6D had a built-in hose-drum unit (HDU), installed under the rearfuselage. In service, the KA-6D usually flew with four or even five externaltanks. It also sometimes carried a buddy tanking pod, either for backup orjust for ferrying it to another base. Since a KA-6D couldn't land on a carrierif the hose got stuck in its extended position, an explosive cutter system wasfitted to get rid of it if necessary.

[4] A-6E / A-6F & A-6G

* Even as the A-6A was being heavily exercised in Southeast Asia, from 1966Grumman was working on a substantially improved variant, the "A-6E", withthe first prototype converted from an A-6A and performing its first flight inits revised configuration on 27 February 1970. Trials going well, A-6A production was ended in December 1970, with Grumman beginning to rollout A-6Es in the fall of 1971.

The A-6E was externally all but identical to the A-6A; it did have newJ52-P-8B engines, but they were just a minor refinement of the old -8Aengines and had the same thrust ratings. The primary improvements were inavionics, primarily a new solid-state AN/APQ-148 solid-state radar system andan AN/ASQ-133 solid-state digital computer system. An AN/ALQ-100 jammersystem was fitted, with an antenna in a slight but noticeable extension ofthe outer LERX on each wing, providing a recognition feature. Apparently theAN/ALQ-100 was also carried on some other Prowler variants, such as theEA-6A, though the antennas weren't fitted in the LERXs.

A total of 240 A-6Es was built new, with 205 additional conversions fromearlier variants, primarily A-6As, though all the surviving A-6Bs and A-6Csended up being A-6Es -- as noted above, a dozen A-6As that had been convertedto A-6Es were then converted to KA-6Ds. The A-6Es were consecutivelyupgraded in service:

• In the mid-1970s, A-6Es were fitted with the "Carrier Airborne Inertial Navigation System (CAINS)", featuring an AN/ASN-92 inertial navigation system replacing the older AN/ASN-31. The CAINS A-6Es featured an additional cooling scoop on top of the left rear fuselage forward of the tail.
• From 1978, 228 A-6Es were updated to the "Target Recognition Attack Multisensor (TRAM)" configuration, featured an AN/AAS-33 turret under the nose containing a FLIR imager ganged to a laser rangefinder / target designator. The B/N lined up a target on a video display's crosshairs for attack with laser-guided bombs; the TRAM system could maintain target lock automatically if need be. The TRAM A-6E was also fitted with a new AN/APQ-156 multimode radar and AN/ASQ-155 computer.
• From the mid-1980s, the A-6E fleet was beginning to show signs of age and particularly wing fatigue, with the Navy consequently awarding a contract to Boeing to design, manufacture, and fit new wings. The replacement wings were of composite construction, except for aluminum control surfaces. The first rewinged A-6E was delivered in 1990, with most (though not all) A-6Es rewinged by 1995.
• The last major update effort for the A-6E was the "System Weapons Improvement Program (SWIP)", which was focused on support of advanced missile armament, including the AGM-65 Maverick air-to-surface missile, the AGM-84 Harpoon antiship missile and its SLAM cruise missile derivative, and the AGM-88 HARM anti-radar missile. Some other improvements were implemented, such as a fire warning and extinguishing system. Not all SWIP machines received the updated wings. A second-phase element of the SWIP program added new avionics, including a Global Positioning System (GPS) navigation satellite receiver and a head-up display (HUD).

* From the mid-1980s, there was work on a follow-on to the A-6E, originallyjust designated the "A-6E Upgrade" but then later the "A-6F". It was to havethe new composite wing, completely modernized avionics, and General ElectricGE F404 bypass turbojets, which were non-afterburning variants of the F404that powered the McDonnell-Douglas F/A-18 Hornet fighter. Threedemonstrators for the "Intruder II", as it was known, were modified fromA-6Es, the first performing its initial flight in its new configuration on 26August 1987.

However, the A-6F program was canceled the next year, 1988, with two moredemonstrators in the pipeline never being flown. The Navy had moved on tothe secret "stealthy" A-12 program, which was canceled itself in 1991 afterthe development effort became clearly "snakebitten". Ultimately, the Navywould focus on the Boeing F/A-18E/F Super Hornet as the "A-6 replacement".There was also talk in the wake of the cancellation of the A-6F of an "A-6G"with the new avionics while retaining the old J52 engines, but the A-6G nevergot out of the "talk" stage. Some sources claim that the Navy's failure toacquire the A-6G was a major blunder -- but what's done is done.

[5] A-6E IN COMBAT

* The A-6E was an important US strike asset in the post-Vietnam era. Itsfirst combat action in this period was in Operation URGENT FURY, the USoccupation of the Caribbean island of Grenada in late October 1983, with A-6Es performing air support for US ground forces. This action wasquickly followed by retaliatory strikes performed on Syrian targets on 4December 1983 as a consequence of the devastating suicide bombing of the USMarine barracks in Beirut on 23 October 1983. The strikes were a fiasco,accomplishing little except for the loss to Syrian air defenses of a VoughtA-7 strike fighter, the pilot being recovered, and an A-6E, one of theaircrew being killed and the other held prisoner by the Syrians for a shorttime.

* Things went better for the Intruder in later interventions. US PresidentRonald Reagan regarded Libyan dictator Moammar Qaddafi as a particular menaceto world peace, Qaddafi being a prominent backer of international terroristmovements. When Qaddafi declared the Gulf of Sidra off the Libyan coast a"zone of death" for foreign ship movements, Reagan, who did not shrink frommilitary confrontations, ordered the US Navy into the area as a heavily-armed"freedom of navigation" exercise. On 24 March 1986, after the Libyanslaunched SAMs against American aircraft, the US Navy hit back, with A-6Eshammering a Libyan corvette with Harpoon missiles -- the first use of theHarpoon in combat -- to then sink it with bombs, and then taking out a Libyanair-defense site with HARMs. The next day, 25 March, A-6Es sank anotherLibyan vessel, damaged a few more, and pounded SAM sites.

In retaliation, on 5 April a Berlin nightclub where US servicemen liked tohang out was bombed, with a US soldier and a civilian killed along withhundreds injured. US intelligence confirmed it as a Libyan-directed act ofterror; in response, Reagan ordered comprehensive strikes by Air Force andNavy jets against Libya. The attack took place on the night of 14:15 Aprilunder Operation EL DORADO CANYON, with A-6Es playing a prominent role in theattacks. The operation was well planned, well executed, and inflictedconsiderable damage on the Libyans. There were hopes it would destabilizeQaddafi's regime; it didn't, but it apparently led Qaddafi to graduallydistance himself from terrorist groups. It certainly did much to enhanceReagan's appeal to the public back home, demonstrating his instinctive graspof military theater.

The next US military operation in which A-6Es were involved was the PersianGulf tanker escort operations of 1987:1988. The war between Iraq and Iranhad been sputtering on violently since 1980, with attacks on oil tankers inthe gulf gradually ramping up. The US finally intervened to help protect theships of Gulf allies from attacks, with A-6Es participating in intermittentexchanges of fire with Iranian forces. The Iran-Iraq War finally fizzled outin a stalemate in 1988.

* The war had left the regime of Iraqi dictator Saddam Hussein in a difficultposition, with antagonisms left over towards Kuwait, and in 1990 the Iraqisinvaded and conquered Kuwait. A US-led coalition ordered the Iraqis to getout; they didn't, and on 17 January 1991 a countermove, Operation DESERTSTORM, started off with an overwhelming air assault. After a month ofpounding, ground forces went into Kuwait on 25 February, sending Iraqi forcesfleeing home in disarray. The A-6E played an important role in the air war,with three shot down, one damaged beyond repair, and one lost in a noncombataccident.

One of the A-6E's most significant roles in the war was as an aerialminelayer, closing off Iraqi shipping channels. This was the last time theUS Navy performed the combat mine-laying mission. At least one A-6E waspainted with a desert disruptive camouflage pattern topside during theconflict. The First Gulf War was the swan song of the A-6E, with the typebeginning its gradual phaseout almost immediately afterward. It was out ofservice by 1996. A number of Intruders ended their lives by being sunk inthe Atlantic off the coast of northern Florida to serve as the core of anartificial coral reef.

[6] EA-6B PROWLER

* From 1964, Grumman worked on an improved ECM version of the A-6, the coreof which was to be the AN/ALQ-99 Tactical Jammer System (TJS) being developedby Cutler-Hammer. The AN/ALQ-99's primary receiving antennas were to behoused in a pod on top of the tailfin, like that on the EA-6A, withadditional antennas on the side of the tailfin. Other jammer gear was to becarried on the underwing pylons.

The extended ECM capabilities were too much for one ECMO, so the crew wasincreased to four, including a pilot and three ECMOs, sitting in a 2x2arrangement on Martin-Baker Mark 7 ejection seats, with the front-seat ECMOdoubling as a navigator. There were separate back-hinged clamshell canopiesfor each of the two rows of seats. The canopies were coated with a thin goldfilm to protect the crew from the powerful emissions produced by theaircraft's jammer systems.

The two extra crew meant a fuselage stretch of 1.37 meters (4 feet 6 inches),and the additional weight led to reinforced wings and landing gear -- theinternal fuel capacity was also increased. The LERX were extended, possiblyto maintain flight trim. An AN/APQ-129 radar was fitted in the nose to helpsupport attacks with Shrikes ARMs or other munitions, with an AN/APN-153Doppler navigation radar fitted as well, along with an AN/ALQ-100 defensivejammer system.

Three A-6As were modified as initial prototypes, with the first flying in itsnew form on 25 May 1968. The first production EA-6B performed its firstflight in November 1970, with service deliveries beginning the next year,1971. Initial production machines had J52-P-8A engines, with laterproduction featuring uprated J52-P-408 engines providing 49.8 kN (5,080 kgp /11,200 lbf) thrust each, and most early machines retrofitted with theseengines.

 ___________________________________________________________________ GRUMMAN EA-6B PROWLER: ___________________________________________________________________ wingspan: 16.15 meters (53 feet) wingspan, folded: 7.67 meters (25 feet 2 inches) wing area: 49.15 sq_meters (529 sq_feet) length: 18.24 meters (59 feet 10 inches) height: 4.95 meters (16 feet 3 inches) empty weight: 14,320 kilograms (31,570 pounds) MTO weight: 29,485 kilograms (65,000 pounds) max speed at altitude: 1,000 KPH (620 MPH / 540 KT) service ceiling: 12,550 meters (41,200 feet) operational range: 1,760 kilometers (1,100 MI / 955 NMI) ferry range: 3,255 kilometers (2,020 MI / 1,755 NMI) ___________________________________________________________________

The EA-6Bs were regarded as sufficiently different from other Intrudervariants to be given a new name: "Prowler". They were available for combatoperations over Southeast Asia in the very last months of the US involvementin the Vietnam War, suffering no losses. 170 new-build Prowlers weremanufactured up to end of production in 1991.

[7] PROWLER UPGRADES / A-6 VARIANT LIST

* The EA-6B fleet was successively upgraded to improved configurations.Deliveries of the "Expanded Capability (EXCAP)" configuration began in 1973,with most earlier Prowlers upgraded to this configuration as well -- as wouldhappen with all later Prowler upgrades. The major improvement with EXCAP wassupport for the AN/ALQ-99 series of jammer pods, which supported eight radiobands instead of four as with their predecessors. EXCAP added several othernew features:

• The AN/ASH-30 "Tactical Electronic Processing & Evaluation System (TERPES)", which gave the EA-6B an "electronic intelligence (ELINT)" capability, allowing it to locate and characterize radar and radio "emitters".
• New jamming modes for the AN/ALQ-99 TJS, with the system upgraded to improved "AN/ALQ-99B" and "AN/ALQ-99C" variants with better reliability.
• A digital recording system.

The "Improved Capability (ICAP)" configuration was introduced in 1975. Itfeatured:

• Major modification of the ECMO consoles to redistribute workload more evenly.
• An improved AN/APS-130 radar set, replacing the AN/APS-129.
• An AN/ALQ-126 defensive countermeasures set, replacing the AN/ALQ-100, which had proven ineffective -- though the AN/ALQ-126 didn't work much better.
• Improved chaff-flare dispensers.

The "ICAP II" configuration followed ICAP from 1980. ICAP II offered:

• The modernized "AN/ALQ-99D" TJS, covering a wider band range.
• Reprogrammable jamming pods whose operational bands could be changed in flight.
• An improved AN/AYK-14 computer replacing the earlier AN/AYK-6.
• Support for the AGM-88 HARM missile. This feature was not actually part of ICAP II at the outset, being introduced later and retrofitted to older machines.
• Improved ECMO consoles.

Late production ICAP II machines featured an updated radio set. The intentafter ICAP II was to move on to the "Advanced Capability (AVCAP)"configuration, which would have not merely featured avionics improvements butalso airframe improvements, particularly uprated engines. However, although ademonstrator was flown, AVCAP was canceled in the mid-1990s.

The Navy focused on less ambitious upgrades, initially with the "Block 89A"upgrade, which was to provide a uniform avionics kit for the Prowler fleet,including a GPS receiver, a new electronic flight information system (EFIS),and improvements to the computer and radio systems. The Block 89A led theway to the "ICAP III" upgrade.

The main focus of ICAP-III was to provide greater integration of theProwler's electronic systems. The three ECMOs were provided with new colordisplays; the pilot got a color display as well, though a smaller one.ICAP-III gave faster response to electronic threats, with the Litton LR-700electronics support measures (ESM) system, featuring antennas on theaircraft's nose, tail, and wingtips working in conjunction with the GPSreceiver system to pinpoint the location of those threats with greateraccuracy, allowing a more effective attack with HARMs or other weapons.

The core of ICAP-III was the "AN/ALQ-218" digital receiver system, replacingthe AN/ALQ-99 system, with the AN/ALQ-218 featuring a "threat library" tocharacterize various threats and provide the most efficient jamming response.ICAP-III was capable of "following" jamming, or jamming at new frequencies asthe threat emitter changed frequency -- while still jamming the originalfrequencies. A digital datalink was also added to allow the Prowler to shareinputs with other platforms.

The first ICAP-III Prowler performed its initial flight in 2001, withproduction initiated in 2003 and initial redeliveries in 2005. Upgrades werecomplete in 2010. Along with ICAP-III, the Navy implemented otherimprovements for the Prowler fleet, for example night-vision goggle (NVG)compatibility, adding support for NVGs plus modification of co*ckpit andexterior lighting.

* The EA-6B was a prominent participant in American conflicts from the end ofthe Vietnam War. There were plans to downsize the Prowler forces from the mid-1990s, but the US Air Force phased out their General Dynamics EF-111A"Spark Vark" fleet of jammer aircraft in 1998, leaving the EA-6B as the "onlygame in town" for US ECM needs. The Prowler force was maintained to providesupport for the Air Force along with the Navy and Marines.

The Prowler was replaced in Navy service by an ECM derivative of the BoeingF/A-18E/F Super Hornet, the "EA-18G Growler", which uses the ICAP-IIIavionics suite. The last service flight of a Navy Prowler was on 27 June2015.

Marine Prowlers were still in action in 2018, flying missions out of Qatar tojam communications of Islamist insurgents in Syria -- but that was the end ofit, the Prowler being retired in 2019. The Marines are thinking of replacingit with a vertical take-off drone that can operate off assault ships, toconduct electronic warfare, early warning, surveillance, and communicationsrelay missions. They also would like the drone to carry light guided weaponsto deal with "time-critical targets" -- that is, that have to be engaged whenspotted, or they'll get away -- and possibly a light cargo load as asecondary mission. In the meantime, the Marines will rely on Navy Growlersfor the ECM mission.

* The list below summarizes A-6 variants and production:

• A-6A (488 built): Initial attack variant, originally "A2F-1".
• EA-6A (15 built, 10 upgrades): Initial ECM variant, originally "A2F-1Q".
• A-6B (19 built): SEAD variant.
• A-6C (12 upgrades): Night jungle fighting variant.
• KA-6D (90 upgrades): Dedicated tanker variant.
• A-6E (240 built, 205 upgrades): 2nd-generation attack variant.
• EA-6B (170 built): 2nd-generation ECM variant.
• A-6F: Unbuilt 3rd-generation variant.
• A-6G: Unbuilt simplified 3rd-generation variant.

A total of 913 A-6s was manufactured in all.

[8] COMMENTS, SOURCES, & REVISION HISTORY

* In the early 1960s, Grumman proposed a single-seat day combat version ofthe Intruder in response to a Navy requirement for a new strike aircraft.The Grumman "G-128-12" was nothing more than an A-6A with a new forwardfuselage, featuring the single-seat co*ckpit and a simpler radar system, plustwin 20-millimeter cannon firing out the nose. It had pretty much the samestores capabilities as the A-6A, though it was envisioned as carryingSidewinder and even Sparrow AAMs for self-defense, implying a radar systemwith Sparrow support. The Navy selected the Vought A-7 instead.

I recall when I was a teenager back in Spokane, Washington in the late 1960sor early 1970s seeing an A-6 performing simulated strike attacks over thecity. It's a vivid memory, but I found it a bit puzzling -- we had Air Forcefacilities near town, but no Navy or Marine air stations in the immediatearea. On mentioning this in an earlier revision of this document, I wasinformed that the A-6 was from Naval Air Station Whidbey Island in PugetSound, in the Pacific coastal regions of Washington State. Spokane was arelatively short hop from NAS Whidbey, and useful for training purposes. Forpractice with live munitions, Intruders usually went to the range at Boardmanin eastern Oregon.

* Sources include:

• THE WORLD'S GREAT ATTACK AIRCRAFT, edited by Roy Wilkinson, Aerospace Publishing 1988. This book appears to be a collection of articles from a 1980s British aviation magazine.
• THE ENCYCLOPEDIA OF WORLD MILITARY AIRCRAFT, edited by David Donald & Jon Lake, Barnes & Noble, 2000.
• AMERICAN SECRET PROJECTS: BOMBERS, ATTACK, & ANTI-SUMBARINE AIRCRAFT 1945:1974 by Tony Buttler, Midland Publishing, 2010.
• "Grumman A-6 Intruder & EA-6 Prowler" by Robert F. Dorr, WORLD AIR POWER JOURNAL, Volume 12 / Spring 1993, 34:95.
• "Grumman EA-6B Prowler" by Robert F. Dorr, WORLD AIR POWER JOURNAL, Volume 30 / Fall 1997, 30:45.
• "Aircraft Gain Upper Hand Over Missiles, For Now" by Bruce D. Nordwall (and following), AVIATION WEEK, 15 November 1999.
• "Precise Jamming Prowler Bound" by Bruce D. Nordwall & Robert Wall, AVIATION WEEK, 2 October 2000, 59:60.
• "Pentagon Mulls EA-6B Upgrades, Preservation" by Robert Wall, AVIATION WEEK, 16 September 2002, 70:71.
• "Jammer Go-Ahead [ICAP-3 LRIP commit]" by Robert Wall, AVIATION WEEK, 07 July 2003, 24.

* Revision history:

 v1.0.0 / 01 may 10 v1.0.1 / 01 aug 11 / Review & polish, added G-128-12. v1.0.2 / 01 jul 13 / Review & polish. v1.0.3 / 01 jun 15 / Changed "WSO" to "B/N". v1.0.4 / 01 may 17 / Review & polish. v1.0.5 / 01 apr 19 / Review & polish. v1.0.6 / 01 feb 21 / Review & polish. v1.0.7 / 01 dec 22 / Review & polish.