The Grumman A-6 Intruder served with the US Navy and the US Marine Corp in an all-weather/night attack role between 1963 and 1997. It was bristling with advanced avionics using multiple computers, and evolved into airborne refueller & electronic warfare variants.
The Intruder replaced the Douglas Skyraider in the ground attack role and did everything that the Skyraider did, while offering high subsonic speeds and an all weather capability.
In turn the Intruder was replaced by the Tomcat using a dedicated LANTIRN pod, and then by the Hornet and Super Hornet, which remain in use today.
Grumman A-6 Intruder
In October 1956 the US Navy issued a formal requirement for an all-weather, carrier-based attack aircraft. The Skyraider had showed the value of aircraft optimised for the ground attack role, but it lacked sophisticated avionics and its slow speed made it vulnerable to enemy fire.
No less than eight manufacturers responded to a Request for Proposals with Grumman selected in January 1958. The lead designer, Lawrence Mead Jr was also a designer on the Lunar Excursion Module and the Grumman F-14 Tomcat.
In fact it was Grumman’s demonstrated ability to deliver the Intruder project, with it’s advanced avionics utilising multiple computers, that contributed to NASA’s decision to contract them to design and produce the Lunar Lander.
The prototype first flew on 19 April 1960 and testing went smoothly, but revealed a need to relocate the speed brakes to the outboard section of the wings. The aircraft’s wing was optimised for high-subsonic speeds, and delivered the ability to carry a large bomb load while offering good manoeuvrability.
The configuration placed the two crew members in a side by side arrangement. The pilot was on the left and the Bombardier/Navigator sat on the right side, slightly lower than the pilot. A synthetic terrain display allowed high speed, low level, all weather capability.
Aircraft were fitted with one of the earliest automatic internal diagnostic systems, known as BACE, which reduced maintenance requirements significantly.
Nuclear weapons were carried by the Intruder and crews trained regularly for this mission, using a Low Altitude Bombing System – Inverted Position (LABS-IP) lofted delivery profile.
Entering service in February 1963, the Intruder became the Navy and Marine Corp’s primary medium attack aircraft for the next 30 years. It was also used as a aerial refueller, designated KA-6D, using a specialised ‘Buddy store’.
The US Air Force did not use the Intruder, instead utilising the F-105 Thunderchief and later the F-111 Aardvark.
The 18,000 lb payload and all-weather/night ability of the Intruder made it invaluable in the Vietnam War, where it was used extensively. Its low level made it vulnerable and 84 aircraft were lost during the conflict. Ten were lost to Surface to Air (SAM) missiles, two were shot down by MiGs, 56 were lost to conventional ground fire and Anti-Aircraft Artillery (AAA), and the remaining 16 were lost to operational causes.
While the Navy aircraft operated from twenty different aircraft carriers during the war, the Marines Intruders operated mostly from land.
Following the Vietnam War Intruders flew in support of the Multinational Force in Lebanon and one of those was shot down over Syria. Three years later Intruders were involved in the bombing of Libya in Operation El Dorado Canyon.
During the Gulf War in 1991, Intruders flew 4,700 missions with three of them shot down by ground fire. Once again they flew close air support and strike roles across Iraq, with Navy aircraft again operating from carriers and the Marines operating from Bahrain.
The final wartime operations for the A-6 were over Bosnia in 1994 and the last Intruders were eventually retired on 28 February 1997.
There were eight prototype and pre-production Intruders and they were ultimately designated YA-6A. One innovation (at that time) that was tested was tilting tailpipes to improve takeoff performance from aircraft carriers, but these were not adopted.
The initial production version of the Intruder. It used the DIANE computer (Digital Integrated Attack Navigation Equipment), which took a few years before it could be trusted to work reliably. 480 were built.
These were A-6As converted for use in a defence suppression role. Much of its fancy avionics were removed and replaced with equipment that could detect and track enemy radar sites.
The aircraft would launch and guide anti-radiation missiles against these targets. The missiles were the AGM-78 Standard and the AGM-45 Shrike. 19 were converted for this role and five were lost to all causes. The remainder were converted to A-6E standard.
Twelve A-6As were converted for specialised night operations over the Ho Chi Minh trail, incorporating advanced radar, low-light TV, forward looking infra-red and ignition-detection systems. One was lost and the remainder were converted to A-6E standard after the war.
78 A-6As and 12 A-6Es were converted into aerial tankers. They often accompanied strike packages on their missions and carried four underwing fuel tanks. The DIANE system was removed and the space used to hold more fuel. When the Intruders were retired this role was undertaken by the S-3 Viking and later by the Super Hornet.
This was the ultimate and perhaps best known variant of the Intruder. It had upgraded avionics, radar, computers and inertial navigation system, among other minor upgrades and enhancements.
The A-6E was fitted with the TRAM – the Target Recognition and Attack Multi-Sensor. Essentially this was a FLIR and laser designator mounted in the nose of the aircraft that allowed the dropping of laser-guided bombs, even on moving targets.
The Prowler was a variant of the A-6A with a stretched fuselage and accommodation for four crew members. It was designed for the electronic warfare role, in which it was highly successful. 170 were built. While no Prowler has ever been lost in combat, as at 2013 50 (!) had been lost in various accidents, killing 44 air crew.
A future article will expand on the role of the Prowler, which was introduced in 1971 and retired in 2015, it’s role taken over by Growler versions of the Super Hornet.
|Aircraft Type||Carrier-based twin jet all weather attack aircraft|
|Role||All weather/night attack, strike and interdiction|
|Crew complement||Pilot and Bombardier/Navigator|
|First flight||19 April 1960|
|Retired||28 February 1997 (US Navy)|
|Unit cost||USD $43 million in 1998|
|Maximum weight||26,580 kg|
|Powerplant(s)||Two Pratt & Whitney J-52 turbojets with 9,300 lb thrust|
|Armament/Payload||Up to 18,000 lb of bombs and/or missiles|
|Range||3,243 statute miles (ferry range)|
|Combat radius||1,011 statute miles with maximum payload|
|Cruise speed||412 knots|
|Maximum speed||560 knots at sea level|
|Claim to fame||Was the world’s most advanced attack aircraft in it’s day|