30 years ago, the RAF deployed its ALARM anti-radar missile. Armada reflects on this weapon and its legacy.
British Aerospace’s Air-Launched Anti-Radar Missile, better known as ALARM, was a child of the Vietnam War. As Richard Scott chronicles in his article ALARM Call: Defence Suppression from the RAF Tornado, the Royal Air Force (RAF) was wise to the experience of US forces vis-à-vis Soviet-supplied Surface-to-Air Missiles (SAMs) during America’s involvement in the conflict. Chris Hobson’s book Vietnam Air Losses: United States Air Force, Navy and Marine Corps Fixed-Wing Aircraft Losses in Southeast Asia 1961-1973 says a total of 205 aircraft were lost to SAMs between 1965 and 1973. These were reaped by S-75 Dvina (NATO reporting name SA-2 Guideline) high-altitude/medium-range SAMs supplied to North Vietnam by the Soviet Union.
Realising the potential vulnerability of its aircraft to such weapons the RAF issued Air Staff Requirement 1228 (ASR-1228) in 1978. Its contents are classified but this probably outlined the need for an anti-radar weapon which could be launched at high speed and low altitude from the RAF’s now-retired Panavia Tornado-GR.1 combat aircraft.
As Mr. Scott’s article explains, British Aerospace and Marconi Space and Defence Systems responded to ASR-1228 with a study of a potential solution before the requirement was mothballed one year later. It was resurrected in 1982 with the two companies proposing a new missile called ALARM. Meanwhile a team involving Texas Instruments and Lucas Aerospace proposed the AGM-88 High Speed Anti-Radiation Missile (HARM). ALARM was selected in July 1983.
ALARM took a novel approach to detecting and engaging hostile radars. The missile would match emissions with an onboard threat library, prioritising the radars the missile’s software ascertained as most threatening. After launch, the weapon climbed to 40,000 feet (12,192 metres). This gave its Radio Frequency (RF) seeker the wherewithal to detect emissions over a wide area. At altitude, the missile would deploy a parachute and slowly descend to Earth while watching for radar emissions. If a hostile radar was detected the parachute would detach, the missile’s motor reignited and it would zoom towards its target. Alternatively, the missile could be programmed to listen out for hostile emissions in a particular area, such as around an airfield for instance.
There was little point a radar operator switching off their equipment if they realised they were under attack from the missile. The RF seeker would remember the radar’s geographical location and head there anyway. A written statement provided to Armada by MBDA, which inherited responsibility for the weapon after the merging of the missile businesses of EADS, Finmeccanica and BAE Systems in 2001, said that one factor which made ALARM unique “was its loitering ability, provided by its parachute and aided by its two-stage rocket motor. Other anti-radiation missiles would be wasted after being launched by flying blind and missing if the target radar was turned off.”
It is instructive that recent HARM derivatives like the Northrop Grumman AGM-88E Advanced Anti-Radiation Guided Missile and Raytheon AGM-88F HARM Control Section Modification weapons have GNSS (Global Navigation Satellite System) enhancements. This lets the missiles to memorise the location of a targeted radar to press home its attack even if the radar is deactivated.
Other tricks up the missile’s sleeve included its support of corridor suppression: An ALARM could be fired to loiter to encourage radars to stay off the air, lest they attract its attention, giving a strike package sufficient time to ingress and egress a target without being illuminated, MBDA’s statement continued. Rather than use a parachute, the corridor suppression mode involved the missile being launched, climbing and then travelling back down to earth in a shallow dive, rather than using the parachute. During the dive, it would search for anything foolish enough to radiate which it had been programmed to attack.
While some “anti-radiation missile warheads could be ineffective if they overshot the target, with the detonation heading into the ground. ALARM was particularly good at attacking the ‘space’ above radars.” Usefully, ALARM could be fired from low level with a loft trajectory which helped keep the launching aircraft below hostile radar, without needing to pop up to perform the attack. This proved particularly useful for the missions ALARM supported during Operation Desert Storm, the liberation of Kuwait.
By October 1990 the missile had completed trials with its maiden deployment just around the corner. Iraq’s dictator Saddam Hussein had invaded Kuwait a few months prior on 2nd August. The US had assembled a coalition of nations to oust Iraq from its new possession, one of which was the UK. Operation Granby, the codename for the UK’s contribution to Operation Desert Storm, included a major deployment by the Royal Air Force which included 51 Tornado GR.1s.
Iraq’s ground-based air defences comprised the very radars ALARM was designed to seek and destroy particularly the SNR-75 (NATO reporting name Fan Song) S-band (2.3 gigahertz/GHz to 2.5GHz/2.7GHz to 3.7GHz) and C-band (5.25GHz to 5.925GHz) and P-35M/37 (NATO reporting name Bar Lock) series of ground-based air surveillance radars. These supplied data to Iraq’s strategic and operational level ground-based air defence systems.
The RAF had nine Tornado-GR.1s from 9 Squadron deploying ALARM flown by crews from 20 Squadron at Tabuk airbase, northwest Saudi Arabia. Open sources state that these jets would typically carry three rounds firing them in loiter mode protecting inbound strike packages. Carlo Kopp says in his analysis of ALARM that the RAF fired 121 rounds during the conflict for a total of 52 ALARM sorties, exhausting stocks by mid-February.
Operationally and tactically relevant electronic intelligence to programme ALARM for the detection of Iraqi radars was supplied by Signals Intelligence (SIGINT) collection flights performed by RAF Hawker Siddeley/BAE Systems Nimrod-R.1P jets believed to be flying from RAF Akrotiri airbase, Cyprus. This was alongside that collected by US SIGINT assets like US Air Force Boeing RC-135V/W Rivet Joint and RC-135U Combat Sent SIGINT planes flying from King Khalid Military City Airport, north-eastern Saudi Arabia.
Given the dangerous offensive counter air missions being flown by the Tornado-GR.1s, which required jets delivering the RAF’s Hunting Engineering JP233 airfield denial weapon, to fly in a straight line at low level over the airfield, robust knowledge of ground-based air defences in the vicinity of an Iraqi airbase was paramount. ALARM could directly target radars providing these air defences, typically SAM and anti-Aircraft artillery batteries, fire control information.
Since then, the missile has been used in every major air campaign involving RAF aircraft where an adversary’s ground-based air defences and integrated air defence systems posed a risk to its success. This included NATO (North Atlantic Treaty Organisation) respective operations Deliberate Force and Allied Force over the Balkans in 1995 and 1999.
A seeker upgrade in the early 2000s expanded the types of radar the missile could engage, while improving its accuracy, MBDA noted. This version was used to “good operational effect” during Operation Telic, the UK’s contribution to the US-led Operation Iraqi Freedom which removed Mr. Hussein from power in 2003. More recently it supported Operation Ellamy, the UK’s participation in the US/NATO Operation Odyssey Dawn/Unified Protector air and sea campaigns to protect civilians from forces loyal to Libya’s erstwhile dictator Colonel Muammar Gaddafi. This was the final war for the RAF’s ALARMs. The missile retired from Royal Air Force service in 2013.
Thirty years on from its maiden deployment and almost ten years after its retirement one can reflect on ALARM’s legacy. Desert Storm and the subsequent conflicts ALARM supported should have been a powerful advertisement, but the missile only secured one export customer in the guise of the Royal Saudi Air Force. Armada records indicate that the RSAF purchased 250 rounds in 1991, all of which were delivered by 1998 for use with the air force’s Panavia Tornado-IDS ground attack aircraft.
MBDA’s statement put the lack of export success down to the fact that ALARM had only been integrated on one airframe, the Panavia Tornado, compared to competing weapons like the AGM-88 which could outfit a plethora: “This made it a challenge to export, despite its advantages and proven operational capability.” Nonetheless, the missile did have shortcomings. Range finding support was needed to enhance its effectiveness and it was vulnerable to electronic counter-countermeasures. Nonetheless, ALARM’s ability to ‘remember’ the location of a targeted radar based on its last transmissions could to an extent obviate this.
Ultimately, “the RAF’s deployment of ALARM in combat proved it was a technologically innovative missile design which could be launched by aircraft with a minimum of missile-specific hardware modifications.” In some senses, it has become a ‘cult’ missile, lauded by those who worked with it but condemned to undeserved obscurity. When the ALARM sounded the missile delivered, entering the crucible of war at breakneck speed as an unsung aegis preserving aircrew lives.