When two SA-7 missiles streaked just metres past a Tel Aviv-bound Arkia Boeing 757-300 500ft (150m) above Mombasa airport, Kenya, on 28 November, it opened a new aspect on the war on terror. Since before last year's 11 September hijackings, governments had been aware of the threat of an attack on a civil airliner with a shoulder-launched, surface-to-air missile (SAM) by al-Qaeda or another group with a grudge against the West. However, since the World Trade Center and Pentagon were hit, resources have been targeted at tightening airport and on-board security to prevent another terrorist takeover of an aircraft. Now the authorities are facing up to the fact that no matter how hard they make it for hijackers to get on to an aircraft, airliners taking off from and landing at airports are still heavily exposed to a SAM attack from the ground.
But is the risk sufficient enough for governments and airlines to change their security policies, and, more importantly, spend millions of dollars on minimising the threat? In some ways, the wonder is that the terrorists have not done this before - at least not recently. Israeli security experts estimate that more than 20 terror organisations possess man-portable, infrared (IR) guided, shoulder-launched missiles (MANPADs). They are relatively cheap - as little as $25,000 - and easy to obtain. Many have found their way into terrorist hands from Afghanistan, where the USA shipped Raytheon Stingers to the Mujahedin in the 1980s following the Soviet invasion. Over 500,000 MANPADs been built worldwide. They have been used successfully numerous times in conflict zones from Lebanon's Bekka Valley to Afghanistan, Angola and Rhodesia. Nine out of 10 combat losses over the past 25 years have been due to IR missiles. According to the International Civil Aviation Organisation, losses include 27 civilian fixed-wing aircraft and 16 military transports. MANPADs are easy to move, hide and use. Their range and accuracy means they can be fired from undergrowth or through the sunroof of a camper van outside an airport perimeter fence. And - unlike the suicide bomber or aircraft hijacker - the terrorists do not even have to sacrifice their lives and can be well away from where the missile was fired by the time security forces arrive. In fact, the only reason the Mombasa attack failed, say Israeli experts, is that the missiles were in poor condition or were fired by terrorists who did not really know how to handle the weapon.
Israel has already begun to take steps to protect its aircraft from future attacks - but it is the only country to do so. Defence minister Shaul Mofaz last week recommended the state allocate $40 million to equip 30 passenger aircraft with countermeasures against shoulder-launched missiles developed by Israeli companies. A feasibility study into the threat from MANPADs was begun before the Mombasa attack, but has been rushed through in the past two weeks. Two Israeli manufacturers, Rafael and Israel Aircraft Industries (IAI) subsidiary Elta, make military countermeasures equipment which they believe can be quickly certificated for use on civil aircraft.
Rafael's Britening uses ultraviolet (UV) sensors to detect a missile's launch and a gimballed turret housing IR sensors that detect the exact missile trajectory. The same turret also houses the IR source that transmits radiation to create a false target. The company's president Giora Shalgi says the kit, which has a price tag of between $1.5 million and $2 million, will be available for civil aircraft "within about four months".
Flare protectionElta, meanwhile, uses a different technology: a civil version of its military IR flare-dispensing system called Flight Guard and the manufacturer says it has applied for US Federal Aviation Administration approval.
Elta's claim that the flares pose no hazard over airports is not shared by most experts. They view with horror the prospect of frequent false alarms causing flares to shoot out of an airliner over a busy airport and believe civil certification in Europe and the USA is unlikely.
There has been a flurry of activity from other manufacturers keen to get in on the act. Elisra is trying to adapt its passive airborne warning system (PAWS) for passenger aircraft. The device uses a sensitive IR sensor and processor to track a missile's exhaust plume radiation, even in cluttered and dynamic environments. According to Elisra, the PAWS has high spatial coverage, angular accuracy and discrimination capability. This enables selective narrow beam countermeasures to be triggered. Rafael and Elisra may end up co-operating on their technologies, with Rafael replacing its UV detection sensors with the IR sensors used in PAWS. Both companies are also co-operating with IAI's Bedek division. It would help to certificate the system and install it on aircraft. IMI is also trying to adapt its Airmor protection system, originally designed for military helicopters.
The drawback of MANPADs, from the terrorist's viewpoint, is that they have limited range, speed and altitude. This means the only time aircraft can be fired on is during take-off, when the hotter engines make it an easier target, and landing. Flares are the simplest way to protect aircraft. Military aircraft launch flares pre-emptively when in a known threat area, or reactively when an onboard missile warning system (MWS) detects the plume of a SAM launch. A civil aircraft would have to launch flares pre-emptively, when the presence of a threat is suspected (impractical in most circumstances), or be equipped with an MWS to launch the flares reactively. Most airliners would require at least two MWS sensors and flare dispensers, plus wiring. Flares themselves are inexpensive - each load costs "a few hundred dollars", according to David Schmieder, a senior research engineer at Georgia Tech Research Institute, which runs an infrared countermeasures course. But the total system cost would be "hundreds of thousands", with large aircraft requiring one dispenser per engine to ensure the flare pattern would fall inside the field of view of the missile seeker, says Schmieder. The possibility of the flares causing fires on the ground is what most alarms those who are sceptical about fitting them to civil aircraft. However, new flares - made of pyrophoric foil, the infrared equivalent of radar chaff - are under development that burn at lower temperatures.
If the threat is from first generation SAMs (see missiles box), the most effective defence is a waveform jammer that is turned on during taxiing and switched off at 5,000-10,000ft (1,500-3,000m), once the aircraft is out of range. One jammer can protect one engine, but the cost of deploying this technology is unknown because it has not been produced in large enough numbers.
BAE Systems is the major producer of IRCM jammers. It builds the widely used ALQ-144A(V) for helicopters and lower-speed fixed-wing aircraft, and the ALQ-157(V) for larger helicopters and turboprop aircraft. It has supplied around 200 of its FAA-certificated ALQ-204 Matador IRCM jammers, developed for the US Air Force in 1982, for VIP Boeing 747s, BAe 146s, BAC VC10s, Lockheed L-1011 TriStars and Gulfstream business jets.
SAM threatIf the threat includes second-generation SAMs, the only effective defence is a directional infrared countermeasures jammer or DIRCM, which gets round the fact that the seeker has a "counter-countermeasure" circuit that rejects flares using several cues, including their spectral signature and kinematic behaviour. They are also more difficult to jam, requiring the beam to be focused and pointed at the missile. The problem is that DIRCM jammers are more expensive and complicated to install.
Northrop Grumman makes the first DIRCM to be fielded in a military application, the AAQ-24(V) Nemesis, developed for UK Ministry of Defence and USAF special operations forces. The Nemesis includes an MWS to detect the missile launches and cue the transmitter turrets. The initial version has a xenon flashlamp heat source. The USAF has selected an enhanced laser-based version of the AAQ-24 as its Large Aircraft IRCM system for installation on Boeing C-17s and Lockheed Martin C-130s. BAE is developing the ALQ-212 Advanced Threat IRCM (ATIRCM) for US Army Boeing AH-64Ds among others. The ATIRCM is a lamp- and laser-based system. Laser jammers are more effective against advanced EO/IR missile threats.
Missile attacksFor Israel to take countermeasures seriously for its civil aircraft makes sense. Missile attacks on civil aircraft are nothing new for the country's main airline. In 1973, Italian police foiled an attempt by Palestinian terror group Black September to launch an SA-7 against an El Al aircraft about to take off at Rome International Airport. In 1985, German and Palestinian terrorists tried to attack an El Al airliner at Nairobi Airport.
After the Rome attack some of the carrier's 707s were fitted with US-made countermeasures systems. Their efficiency, however, was limited and they overburdened the aircraft's electrical system. Eventually the systems were dismantled and, since then, no Israeli airliner has had countermeasures fitted. However, advances in technology, coupled with the higher security threat and the country's small fleet - El Al has 27 aircraft and Arkia 11 - means equipping aircraft following the latest attack is feasible.
In the USA and elsewhere, there have been noises about exploring countermeasures for civil aircraft since Mombasa, but if anyone is making it an urgent priority, they are keeping quiet about it. Two prominent US senators last week entered the debate. Richard Shelby, incoming chairman of the appropriations transportation subcommittee, says he and his colleagues will examine countermeasures next year during hearings on aviation safety. Meanwhile, New York senator Hillary Clinton called for a "national plan" to protect aircraft from missile attacks. Beyond that, the response has been muted. The Transportation Security Administration, created in the wake of 11 September, says it has been "working for several months with a number of federal agencies on this issue", following an FBI warning in May about the threat of MANPADs to airliners. But it will not disclose what measures it has taken for security reasons. The UK is similarly reticent about the latest threat. Its Department for Transport simply says that since 11 September the government has been prepared for "a number of possible threats to security".
Airline opinion is that the cost of installing expensive countermeasures far outweighs the risk of being attacked. The International Air Transport Association says that the cost of equipping the world's international airline fleet with missile countermeasures, at between $1 million and $3 million a time, would be "prohibitive". The US Air Transport Association says such measures are workable only if taxpayers foot the bill.
It seems that until a civil aircraft is actually downed by a MANPAD, countermeasures will have to battle with a host of other security measures on the priority list of politicians and regulators as they continue to fight the multi-fronted war on terror.
Source: Flight International