Self-protection demands grow: in common with many other aspects of defence, that of self-protection for aircraft is constantly being revised to counter new threats. That may be just fine for industry anticipating extra business but can prove to be a dilemma for procurement agencies that must ultimately decide what level of protection can be afforded and when.

For many years, self-protection (SP) systems have comprised passive Radar Warning Receivers (RWR) linked to powerful transmitters designed to alter the flight path of an incoming missile, or alternatively to trigger the deployment of chaff or flares. Some systems are integrally fitted in the airframe but more often are pod mounted to accommodate the various electronic receivers, antennas and transmitters necessary to deal with different threats.

Fixed-wing Protection

Now gathered into the Northrop Grumman product line, the AN/ALQ-131 electronic countermeasures (ECM) pod was first fielded in 1970 but has since been the subject of regular software updates. Fitted to aircraft types as diverse as the C-130, F-16 and A-10, the AN/ALQ-131 pods have been upgraded using data gathered during Desert Storm, or simply as a result of the latest threat evaluation. But such upgrades cannot be performed continuously and are usually provided every two years.

When planning SP system upgrades, the possibility that the modernised equipment could have compatibility problems with other onboard and offboard systems must be considered and if necessary be subjected to tests. In the case of the latest Block Cycle II update for the AN/ALQ-131, approval for US Air Force aircraft was only given after extensive flight tests were conducted in 1998 and 1999.

With combat aircraft such as the F-16, F/A-18, F-4 and others supplied to users in many parts of the world, it is no surprise that competition to provide them with SP systems has been intense. Consequently, major suppliers such as Raytheon, have also enjoyed success with alternative ECM systems, the AN/ALQ-187 being fitted to several aircraft types. This is mounted internally to eliminate drag and avoid taking up an external station better used to carry weapons or fuel.

The AN/ALQ-187 is a fully automatic system that detects and defends against surface-to-air missile and gun systems as well as air-to-air weapons, countering pulse, pulse-Doppler or continuous wave emitters. Building on its long experience in the provision of SP systems, Raytheon recently secured a substantial order to supply the Hellenic Air Force F-16 Block 52+ fighters with its Advanced Self-protection Integrated Suite. This includes the ALQ-187 jammer, together with the ALR-93(V) threat warning system and ALE-47 chaff and flare dispensers.

Missile warning systems designed to detect infrared-guided missiles are now as essential as RWRs and CMC's. The AN/AAR-44A system makes use of two sensors to provide full 360[degrees] coverage. Compact and lightweight, the AN/AAR-44A has been designed for use on all types' of airborne platforms including unmanned air vehicles (UAVs).

Needless to say, combat aircraft marketed by Russia can be supplied with state-of-the-art SP systems. So Sukhoi Su-27SK fighters supplied by Irkut to the Indian Air Force are equipped with a new ECM suite that provides individual, mutual and group protection. The SP package includes an RWR cockpit display, a chaff and IR dispenser and multi-mode jammers mounted in wingtip pods.

But ECM, chaff and flare are not the only means of providing protection for aircraft; towed decoy systems are gaining in acceptance, although some platform compatibility problems have arisen. For example, the ALE-55 fibre-optic towed decoy (Fotd) developed by BAE Systems has been selected by Boeing to equip MC/AC-130s used by US special operations forces, but the same system encountered problems when fitted to the Boeing B-1B as part of an update proposal.

FOTDs have the advantage over conventional decoy systems by their luring missiles to a greater distance from their targets. A successful system example being the ALE-55, which connects to an ITT ALQ-172 high-band jammer or BAE System's ALQ-214 radio frequency countermeasures system on the AC-130. A snagged brake is said to have prevented the ALE-55 from being reeled out from the B-1, but although the problem has been resolved, Raytheon has received funding to develop an alternative FOTD based on its earlier ALE-50. The fact that the selection of an FOTD for the B-1B is not expected until 2005 is an example of the time needed to develop and equip combat aircraft with the very latest of decoy systems.

The X-Guard RF towed decoy system marketed by Rafael is claimed to defeat modern tracking radars and missile homing seekers. It is retrievable for multiple use and features solid-state active array transmitters, but in a further step to confuse air defences, expendable free flying decoys have been developed by such companies as Raytheon and Northrop Grumman.

Development of Miniature Air Launched Decoys (Maid) began in the 1990s, and Raytheon recently secured a US Air Force contract to begin production of some 1500 in 2008. Up to 16 Maids can be carried by a B-52. After launch they will fly pre-programmed routes to generate the radar cross-section of the bomber. Other Malds from the initial order will be carried by F-16s. Bidders for the contract included Boeing, Lockheed Martin and Northrop Grumman, the successful Raytheon design drawing on some of the company's technology used on its Paveway and EGBU-15 precision guided weapons.

But Israel Military Industries (IMI) is also with the market leaders in the production of free-flying decoy systems, having supplied the US Navy with its tactical air-launched decoy (Tald). Indeed, the wreckage of an expended Tald, which fell on Baghdad during the recent conflict, was judged to be a missile. However, around 6000 Talds have been supplied to the US Navy which first used them in the 1991 Gulf War and has since ordered a further 500 improved models.

If Northrop Grumman lost out to Raytheon in its bid for the Maid contract, despite having demonstrated its capability under a Darpa programme, its AAQ-24(V) Nemisis directional IR countermeasures (Dircm) system is faring better. It is claimed to be the only such system in series production and is currently deployed on C-130, BAe 146 and EH-101 aircraft. The system makes use of the company's AN/AAR-54(V) missile warning system which can be interfaced to a chaff/flare dispenser system, or as in Nemesis, direct an intense narrow beam of IR energy to defeat the missile. Northrop Grumman has been selected to supply its Dircm technology to meet a US Air Force requirement to protect C-17 and C-130 transport aircraft, the former making use of three laser transmitters.

Defeating Invisible Foes

Gone are the days when the ability to aim a weapon while out-manoeuvring the enemy could determine the outcome of a dogfight. Nowadays, the challenge to a fighter may come from an aircraft beyond visual range, while a transport aircraft pilot may never see the manpads operator tracking his target. So time in a simulator will help to increase alertness, while rangeless air combat training systems bring added realism to air exercises.

But there is still a place for good old-fashioned practice against towed targets and a surprising number of companies around the world provide such a service on a contract basis. This saves having to acquire targets and threat simulators, as well as the high-performance aircraft and crews to operate them. However, if budgets impose limitations on the number of annual flying hours for such 'live' training, full mission simulators can provide pilots with sweat-inducing scenarios within a dense threat environment.

Low/Slow Can Survive

Flying a transport helicopter over a featureless desert offers little in the way of shielding by the terrain, so increasingly aircrews are getting the added assurance of protection in the form of SP suites. Most make use of a classic Missile Approach Warning System (Maws) linked to chaff and flare dispensers.

However, although former Soviet Mi-24s made liberal use of such decoys during operations in Afghanistan, their losses were still relatively high as small rebel units became skilled in the use of manpads--often including Stingers supplied by the Americans. But Israel has become accustomed to operating in such a hostile environment and its industry has developed a number of helicopter SP systems.

SP suites for both Western and Eastern helicopters have been produced and sold by Elta, but BAE Systems' recent sale of its Hidas (Helicopter Integrated Defensive Aids Suite) for installation on Kuwaiti AH-64Ds marks its breakthrough into export markets. This system will equip all British Army Apaches and operational experience will give added credibility to the Hidas, although meanwhile, it is Northrop Grumman which has supplied Royal Air Force (RAF) Merlin helicopters with it laser-based Nemisis system.

Training Helicopter Crews

Until recently, helicopter pilots were expected to avoid enemy defences by making use of the terrain so that line-of-sight engagements could be delayed until it was too late to bring manpads to bear. However, it is now recognised that SP systems should be fitted to all types.

But that is not to say that nap-of-the-earth flying skills can no longer be used to outwit enemy defences, so much emphasis in training continues to be placed upon avoiding ground defences. The Mission Command Trainer (MCT) developed by Evans & Sutherland (E & S) provides an affordable simulation system, which at first glance appears to be very basic, with no claim to faithfully reproduce a specific helicopter cockpit.

However, users soon find that any complacency induced by the apparent simplicity of the MCT may experience the mission being aborted by an incoming missile. Britain's School of Army Aviation commissioned an upgrade to its Aviation Command and Tactics Trainer, derived from the MCT. This replaced the existing image generators with E & S' PC-based Ensemble visual system, adding forward-looking iafrare4t and night vision goggle capabilities to the existing databases.

Thus a day/night capability has been provided to the system, and its use for various courses is an endorsement to the claim that honing SP skills does not necessarily call for a full flight simulator. But a new and ingenious in-flight EW simulator can also provide SP training. This has been developed by the Elisra subsidiary of BVR. The system generates ground and airborne threats through the onboard EW system of Israeli Air Force CH-53-2000 helicopters, enabling crews to increase their ability to operate over areas well protected by air defence systems without getting hit.

The low and slow nature of helicopter operations has enabled UK Army Lynx and Apache crews to make use of Saab's BT46 direct fire weapons effects simulation (DFWES). The permits use of an eye-safe class 1 laser during live firing and tactical training for British Army Air Corps' Lynx and Apache crews.

Future Trends

The pattern of air warfare is changing, with reliance upon UAVs likely to increase, both for intelligence gathering and as a means of delivering ordnance. But the increased capability of such aircraft comes at higher unit cost, so automatic SP systems for them will have to become the rule rather than the exception.

Manned aircraft have reverted to the use of height to operate beyond the range of most enemy defences often rendered impotent by the destruction of their radar and command facilities, but helicopters, tactical combat and transport aircraft must still fly within range of air defence missiles. Consequently, there are few military aircraft that today should be deployed without adequate SP systems.

RELATED ARTICLE: Civil aviation self-protection systems.

Civil aircraft are increasingly used on an ad hoe basis to fly men and materials in support of military operations around the world. Clearly such aircraft may be vulnerable to missile attack from irregular forces or others opposing the presence of foreign troops, and there must be a case for fitting them with SP systems. Indeed, the failed terrorist attempt to shoot down a Boeing 757 taking off from Mombasa airport with two SA7 manpads last November has revived earlier calls for civil airliners to be afforded protection against such threats.

Given that it was not the first attempt to fire a missile at an Israeli airliner, it is no surprise that the country's industry has been quick to offer an SP solution. But less publicised missile attacks on civil aircraft had previously taken place, some resulting in loss of life and as a result, a relatively small number of aircraft have been afforded SP systems. Most have equipped aircraft used by heads of state or senior government ministers. IAI's Elta System exhibited its Flight Guard system at this years Paris Air Show installed on a company Boeing 737 but this makes use of chaff and flare decoys that some consider unlikely to gain approval from civil aviation authorities. Flight Guard is based on the company's EL/M-2160 already installed on more than 150 aircraft including several operated for heads of government.

The MUlti-Spectral Infrared Countermeasure (Music) system developed by E1-Op employs a narrow laser beams to jam a missile's guidance system, this is a technology also employed by Rafael in its Britening system. Employing proven E-O systems, Britening is derived from the company's Aerogem E-O SP systems and is intended to provide protection against anti-tank missiles during taxi, as well as against manpads during take-off, climb, approach and landing.

Northrop Grumman, BAE Systems and Analogic teamed with Sanders Design are among others offering SP systems for civil aircraft. But with airlines and airports already burdened by rising security costs, the airliner SP systems price of around $ one million could deter their widespread adoption. However, system unit costs could reduce if other aircraft manufacturers follow Airbus' example in issuing an RFI on manpads countermeasures systems and this leads to their adoption as a standard fit.