GRAHAM WARWICK / WASHINGTON DC
Whichever approach the USA takes towards protecting airliners against shoulder-launched SAMs, cost to airlines will be the major factor
While the US government maintains there is no credible information on a missile threat to US airliners, efforts to develop the means to protect commercial aircraft from man-portable air defence systems (manpads) are gathering pace. One reason for the urgency is the clear evidence of a missile risk to US transport aircraft in certain parts of the world.
If the terrorist manpads threat was spotlighted by the failed attack on an Israeli airliner flying out of Mombasa, Kenya in November 2002, it was reinforced by the missile strike on a DHL freighter leaving Baghdad, Iraq last November and two subsequent attacks that damaged US Air Force Boeing C-17 and Lockheed C-5 transports departing Baghdad.
The US forces' inability to guarantee the security of Baghdad airspace is one reason the USA may be forced to field missile countermeasures not only for military but also for civil transports operating into Iraq, whether commercially or under government contract. The USA has similar security concerns about several other airports around the world.
A decision to equip airliners with countermeasures - whether it is all 6,000 aircraft in the US jet fleet, just the 300 widebodies in the Department of Defense's civil reserve air fleet, or only those operating into Iraq - remains a year or more in the future. First the US Department of Homeland Security (DHS) must demonstrate that it is technically, operationally and economically feasible to adapt military countermeasures technology for use on commercial aircraft.
To that end, the DHS has embarked on an aggressive counter-manpads programme to develop anti-missile systems for airliners. The plan was presented to Congress in May last year, a request for proposals was released in October and in January the DHS announced that three teams had been chosen from 24 bidders for six-month preliminary-design contracts. By mid-year, the department plans to award two of the teams 12- to 18-month prototype-demonstration contracts. When the work is complete, the DHS plans to provide the administration and Congress with a recommendation on the most viable solution to defend commercial aircraft against shoulder-fired missiles.
Although a review of available technologies by the White House Office of Science and Technology Policy identified an onboard jammer, or directed infrared countermeasures (DIRCM) system, as the most promising, the DHS has hedged its bets and selected two teams offering DIRCM solutions and one using more-traditional offboard infrared decoys - the approach already selected by the Israeli government to protect that nation's airliners against missile attack (see panel P33).
Teams led by BAE Systems and Northrop Grumman are proposing commercial derivatives of DIRCM systems now in the early stages of production for the US military. The third team, led by United Airlines, is offering a version of a decoy-based system developed by Avisys to protect head-of-state widebody aircraft and now undergoing flight testing on an Airbus A340. The different strengths and weaknesses of the two approaches in a commercial-airline application will be explored during the six-month first phase of the counter-manpads programme.
BAE, teamed with Delta Air Lines and Honeywell, is offering a version of the ALQ-212(V) Advanced Threat Infrared Countermeasures (ATIRCM) system developed for US Army helicopters. Northrop Grumman, which also has a US airline on its as-yet unnamed team, is proposing a version of the AAQ-24(V) Large Aircraft Infrared Countermeasures (LAIRCM) system in production for US Air Force C-17s and Lockheed Martin C-130s. The 12-member United team is offering the Commercial Airliner Protection System (CAPS), based on Avisys's WIPPS (Widebody Integrated Platform Protection System).
Protection guidelines
In its October solicitation, the DHS called for a system capable of protecting aircraft of Boeing 737 size or larger during the 10min after take-off and 10min before landing. The system must provide 360¡ coverage against infrared-guided surface-to-air missiles ranging from the first-generation SA-7 to third-generation SA-18, with a success rate of 90% or better against multiple-launch attacks and 80% for two simultaneous engagements. The Kenyan attack involved two missiles, both earlySA-7s missing the Arkia Airlines Boeing 757, while two later-generation missiles may have been launched against the DHL Airbus A300 at Baghdad, one of which extensively damaged the left wing.
The DHS's performance objectives place a heavy emphasis on minimising the life-cycle costs, as the US government is expected to pay for the systems and their installation but the airlines will then have to bear both the direct and indirect operating costs. All three teams say their proposed systems are within the unit cost target of no more than $1 million for the 1,000th system delivered, and "well below" the DHS's operational cost target of less than $500 per take-off and landing. "It has to be," says Burt Keirstead, BAE counter-manpads programme manager. "That number is very high by airline standards and will not help their bottom line."
The teams are coy about costs, but Northrop Grumman has previously estimated that its system would cost $1.9 million installed for a 300-aircraft fleet, dropping to $1 million for 1,000 aircraft, while the operating and maintenance cost would be $26.50/h for a 300-aircraft fleet, falling below $13/h for 1,000 aircraft. Meanwhile, members of the United team have put the unit cost of the decoy-based system at under $500,000 for the 1,000th unit, but offered no estimate of the operating cost.
Life-cycle cost will be driven largely by maintenance in the case of the DIRCM systems and expendables in the case of the decoy-based CAPS - and both will be heavily influenced by the false-alarm rate of the sensors used to detect and track missiles launched at the aircraft. The cost in wasted expendables is clear in the case of the decoy-based system, while the laser-based DIRCMs consume power and not much else. But they do incorporate a complex gimballed turret that wears with movement and requires maintenance.
The DHS itself says existing military DIRCMs have a mean time between failures (MTBF) of roughly 300h, totally inadequate for airline use, although both BAE and Northrop Grumman say their commercial derivatives will meet the department's requirement for a minimum 3,000h MTBF in airline service. Reliability affects availability, and the DHS requires that the countermeasures system should be operationally available without imposing take-off and landing delays.
Operating costs will be driven largely by the drag and weight of the countermeasures systems, as they are intendedt o operate autonomously and aircrew training costs should be minimal. Extra drag equates to added fuel consumption and cost, while additional weight amounts to lost payload and revenue. The DHS has set a weight limit of 450kg (1,000lb) and a maximum drag penalty of 1%. Avisys says its system weighs 115kg and is essentially conformal and drag-free. The DIRCM systems, housed in under fuselage "canoe" pods, will weigh around 140kg and incur a drag penalty that has yet to be accurately defined.
Whether DIRCM systems can be transitioned successfully from military to civil aviation use is the biggest question facing the DHS. Despite the lingering doubts about their suitability for commercial airline operations, these laser-based onboard jammers, which work by dazzling the missile's infrared seeker, promise to be more effective than offboard decoys against a wider range of manpads. And while decoys may be a less expensive solution, there are question marks over their effectiveness and their safety.
Avisys believes it can address most of the concerns with the CAPS, which combines multi-spectral sensors with special-materials decoys (SMD). Using both passive ultraviolet (UV) and active pulse-Doppler (PD) missile warning sensors reduces the false-alarm rate, says senior vice-president Dennis Derr, while SMDs burn cooler and faster than conventional magnesium flares, reducing the risk of igniting ground fires. SMDs are also "visually covert", avoiding the risk of panicking the passengers or public, blinding other pilots or drawing additional attacks.
False alarms
Derr says using passive imaging and active radar sensors to validate each other reduces the false-alarm rate to "an almost statistically insignificant" one in 80,000h. This compares with the DHS's stated target of one in 17h or one in 100 take-off and landings, whichever is fewer. Both of the DIRCM systems are cued by passive UV missile-warning sensors that detect the launch plume, then use infrared sensors to track the missile and point the laser. This reduces false alarms, says BAE.
SMDs, developed for the US Air Force by team member Alloy Surfaces, use a self-igniting metallic material that rapidly oxidises. Burning at 800°C (1,500°F) compared with 2,000°C for a magnesium flare, the foil-like decoys form an infrared "cloud" that draws the missile's seeker away from the aircraft. SMDs are not visible in daylight and produce only a faint red glow at night. The "politically safe" decoys burn for 2s compared with 6s for flares and are fully consumed, says Derr, so nothing can hit the ground and start a fire.
Avisys is now flight-testing special-materials decoys on a WIPPS-equipped A340 for a head-of-state customer. The widebody aircraft is fitted with five EADS/LFK AAR-60 ultraviolet missile-warning sensors, four Thales MWS-20 pulse-Doppler radar sensors and eight ALE-47 countermeasures dispensers. Sensors and dispensers are mounted in the A340's wing/bodyfairing, fore and aft of the wing, covering the lower hemisphere.
Changes required for the CAPS proposal include replacement of the German-supplied UV sensors with the lower cost AAR-47(V)1 produced by US firm Alliant Techsystems. Derr says talks are under way to produce a demilitarised version of the Thales PD sensor in the USA to meet DHS requirements. One disadvantage of the CAPS approach is the certification complication introduced by installing active radar sensors on a commercial aircraft, but Derr questions the passively directed DIRCM's ability to operate in all weathers, including heavy rain or high ozone.
SMDs, meanwhile, are less effective against early-generation missiles than magnesium flares or DIRCMs. This may require aircraft to carry a "cocktail" of conventional and special-materials decoys to provide the full range of protection sought, Derr says. This would seem to erode some of the safety advantages claimed for CAPS. Exporting SMDs also requires a government-to-government agreement, but similar restrictions are expected to apply to the sale of DIRCMs to non-US airlines. The teams expect a US export policy on commercial-aircraft countermeasures systems to be developed during Phase 1 of the counter-manpads programme.
Onboard jammers
Avisys accepts that onboard jammers are the long-term answer to the manpads threat, but doubts the technology is mature enough yet for commercial airline use, although its WIPPS is designed to interface with a DIRCM. The company is proposing that long-haul, widebody aircraft flying into high-threat areas be equipped now with offboard decoys and upgraded later to co-operative onboard/offboard systems. "Narrowbody aircraft do not necessarily require DIRCM, and offboard decoys are the right solution for them," says Derr.
Determining the commercial suitability of the competing countermeasures systems is the focus of the six-month first phase of the counter-manpads programme. Tasks to be performed under the $2 million Phase 1 contracts include developing concepts for the system's operation and support, producing a design that meets both protection and certification requirements, and providing high-fidelity analyses of reliability, maintenance and life-cycle costs.
Protecting secrets
Issues to be addressed include how the teams plan to protect and support any sensitive military technology in the systems within the commercial aviation infrastructure. Another issue to be determined is whether airlines will be allowed to despatch aircraft with the countermeasures system inoperative, and under what conditions. Also to be resolved is what information the system will provide to the crew. The DHS wants the system to notify the ground of a missile launch, and wants the launch location to be recorded and, if possible, downlinked in flight.
Under the second phase of the programme, two teams will each receive a $45 million contract to develop, flight-test and certificate two prototypes of their system on a widebody aircraft type. Operational testing may include live-fire aerial cable testing, similar to that already performed on the military ATIRCM and LAIRCM, to validate each system's performance against realistic missile threats. Phase 2 will include US Federal Aviation Administration certification of the systems ready for fleet installation, if mandated by the US government.
While the DHS is no longer considering ground-based and other solutions under the counter-manpads programme, other US agencies continue to evaluate different approaches to meeting the missile threat. The US Air Force is looking at the escort DIRCM, or E-DIRCM concept under which DIRCM-equipped platforms provide a protective umbrella for other aircraft during take-off and landing. And the US Navy is to test a ground-based electro-optical sensor grid capable of detecting missile launches and datalinking the information to countermeasures-protected aircraft.
While the USA lacks specific information on missile attacks planned against its airliners, the manpads threat is of "credible concern" to the DHS and the development of countermeasures systems is just one response. But it is the one likely to have the greatest impact on the airlines themselves.
Source: Flight International
