December 2006
 

New challenges for air defence

Skyshield system to thwart terrorist attacks

Fresh reports of fatalities, injuries and serious damage due to mortar and rocket attacks on ISAF peacekeepers in Afghanistan and troops taking part in Operation Iraqi Freedom reach us almost daily. Around 30 nations operate some 70 installations ranging from forward operating bases to small Provincial Reconstruction Team (PRT) sites in Afghanistan; and 150,000 soldiers from 27 nations have been deployed in about 180 different locations in Iraq.

Insurgents attack these facilities with 60 mm and 81 mm mortars or with 107 mm rockets fired from improvised grenade and rocket launchers. The accuracy of these weapons is frequently poor, but the threat to peacekeeping forces is considerable. Much to their chagrin, modern, well-equipped armed forces frequently find that they lack an adequate means of countering such attacks. Apart from taking cover and letting loose with counter-battery fire, often the only other option is to retaliate from the air.

However, none of these solutions is really conducive to protecting vulnerable facilities – and can even undermine the viability of peacekeeping missions. Artillery observation radar cannot deliver continuous 360° reconnaissance coverage or the necessary advanced warning. Besides, opening fire on suspected enemy positions in built-up areas and in peacetime can be problematic or even out of the question.

Written by Fabian Ochsner of Oerlikon Contraves AG in Zurich, this article underscores the newfound importance of air defence technology in dealing with the challenge posed by insurgent forces armed with artillery. In fact, air defence artillery is the only way today of coping with this threat – and this is leading to a veritable renaissance of this technology. Cannon-based air defence solutions have always been the prime focus of Oerlikon Contraves, whose innovative Skyshield system makes it the technological leader worldwide. This leading-edge product is ideally suited to the new task at hand.
 

A full colonel in the Swiss Air Force, Oerlikon Contraves AG's Fabian Ochsner has immense experience in ground-based air defence systems.

Defence experts in the USA had already recognized the problem in the 1990s. The Enhanced Area Air Defence System (EAADS) programme – consisting of a network of sensors and effectors for engaging all types of hostile targets in the air – defined the active engagement of incoming artillery shells and rockets as an important and central requirement. The term "ordnance-based combat" as a supplement to the "platform-based" variant was coined at that time. This created a new paradigm for ground-based air defence, supplanting the long-standing search for standoff engagement solutions.

However, planning engineers were overly optimistic about the technologies available at the time. The weapon originally intended for the task was a high-energy laser that was supposed to engage large numbers of approaching targets at a rapid rate. Large sums of money were invested in this technology; yet the Tactical High Energy Laser (THEL) programme, which was to produce a battlefield-capable 100kW-class laser, was discontinued at the end of 2004 owing to unsatisfactory results. Experts believe that a laser of this type will not be available before the end of the next decade.

Since there was still no effective countermeasure against mortar attacks – especially in Iraq – military planners were lambasted for betting on the wrong horse. An urgent search for alternatives got under way, not just in the US but elsewhere as well since the operators of air defence installations in Afghanistan faced similar problems. At the end of 2004 NATO established a new working group dubbed "Defence Against Mortar Attacks" (DAMA). Made up of representatives from NATO member states directly concerned (e.g. the US, Germany, the Netherlands, Spain, Canada, France, Great Britain, Greece and Denmark), the working group addressed seven relevant areas for neutralizing mortar attacks. These are:

• Prevent: prevent an attack from taking place
• Detect: detect when and where a mortar will be fired
• Warn: give warning and take cover
• Intercept: engage and destroy the mortar in flight
• Protect: avoid damage through better construction techniques
• Attack: attack the fire position
• Command and Control: ensure mission command

The task of the DAMA working group: to identify capability gaps and prepare possible solutions for addressing them. After a final presentation of the solutions identified, the working group is to be dissolved in spring 2007.

In the US, the frenzied search for quick solutions led to the evaluation of two cannon-based air defence systems. Both were tested in 2004 to determine their ability to engage rocket, artillery and mortar (RAM) targets. The results confirmed the suitability of air defence cannons as effectors in such missions. The following systems were tested:

• Raytheon's Phalanx Close-In Weapon System (CIWS), equipped with a 20 mm Gatling gun. The system was originally designed to engage anti-ship missiles at close-range. It fires a burst of projectiles toward the target at high rates (4,500 rounds per minute). In series of up to 800 mine grenades, it demonstrated its effectiveness against 60 mm and 81 mm mortars as well as 120 mm artillery rockets. Weighing 24 tons, the system is installed on many US Navy vessels, and can be mounted on a heavy-duty wheeled platform for ground operations.
   
• Oerlikon Contraves' Skyshield air defence system. Developed by the Rheinmetall subsidiary between 1992 and 2003, this system anticipated the change in paradigm outlined above, introducing a special ammunition technology for engaging incoming munitions as well as platforms. The ammunition carries a lethal payload of 152 tungsten projectiles weighing 3.3 g each, which rely on kinetic energy to carry out their task; the electronically programmable fuse ejects the payload approximately 20 metres ahead of the target. This creates a dense cloud of projectiles which not even the smallest target can slip through.

The Skyshield system, designed for close-range air defence of stationary installations against guided munitions and small aerial vehicles, is the successor to our familiar Skyguard 35 mm fire unit in service worldwide. The system consists of a command post with two operators, an unmanned radar sensor as well as two unmanned 35 mm revolver guns. The fire unit is engineered for sustained operations in difficult climate conditions, e.g. for protecting forward operating bases.
 

Automated air defence technology: the high-performance Skyshield generation with revolver guns.

Skyshield was initially conceived as an air defence system, a task which it performs extremely well. Various tests have confirmed the system's potential for counter-RAM operations: in the USA and Germany, field trials have shown that the fire unit is able to detect and identify RAM targets, and that ammunition originally designed for air defence purposes can hit these targets. However, owing to the relatively low weight of the sub-projectiles, they generally proved incapable of shooting down RAM targets; at best, the grenades or missiles were deflected from their flight path. It has since been shown that heavier sub-projectiles can destroy incoming rocket-propelled grenades.

Further tests involving new capabilities focus on the automatic identification and classification of ballistic airborne targets as well as ways of computing the firing point and the predicted point of impact. These functions not only allow enemy firing positions to be engaged, e.g. by despatching a nearby patrol to the scene, they also provide advance warning to persons near the predicted point of impact. Skyshield features open interface architecture and can therefore be integrated into existing command systems. The system thus makes a valuable contribution to meeting the following four DAMA tasks:

• Detect
• Warn
• Intercept
• Command and Control

As they were already available, the Pentagon decided to deploy Phalanx systems in Iraq. Following a procurement process carried out in record-breaking time, the systems were taken from the US Navy's production line. Augmented with a command and control system for ground-based air defence as well as a multitude of additional sensors, the resulting C-RAM system was subsequently tested and accepted. The military was willing to put up with certain obvious drawbacks (i.e. the short effective range and the heavy guns) because of the urgent need for a solution to the RAM problem. In the longer term, mobile guns with greater ranges are to replace the current stopgap solution.

In order to prepare Skyshield for the special task of protecting forward operating bases, Oerlikon Contraves is:

• redesigning its Ahead ammunition with sub-projectiles that are sufficiently heavy to destroy mortar rounds, grenades and missiles reliably;
   
• implementing a very high degree of automation, enabling the system to operate 24 hours a day for many years with minimum personnel. This includes automatic target detection and engagement processes which the operator only has to monitor;
   
• and networking and integrating the sensors into local air and ground systems in order to allow central operational control of the C-RAM system.

In deploying Phalanx, the United States has taken a first step towards active protection of its troops and installations from the RAM threat. A number of nations with troops in Afghanistan are currently evaluating this threat as well as possible countermeasures. Germany, the Netherlands, Great Britain, Canada, Finland and Spain have all addressed the problem, and are focusing on the role of cannon-based air defence to counter present and future threats. Countries which previously opted for guided missile solutions to meet their air defence needs now face a capabilities gap that can only be addressed with cannon-based technology.

Rising numbers of rocket and mortar attacks have triggered urgent efforts in a number of the nations affected. Rheinmetall is the first port of call when it comes to protecting forward operating bases and vital assets from asymmetric threats in the air and on the ground.

Protective Shield is an all-embracing concept that masters all types of threats. Forming an integral part of this concept, Skyshield is capable of operating autonomously as a Camp Protection System (CPS), effectively thwarting the threat from the air. A significant future market will open for Skyshield once its effectiveness against RAM targets is officially demonstrated in 2007. Oerlikon Contraves is superbly placed to take up this challenge. As a result, we will be able to put our capabilities as the world's leading manufacturer of cannon-based air defence systems to highly effective use for many years to come.


Fabian Ochsner

Fabian Ochsner, 49, is head of Ground Based Air Defence System Management at Oerlikon Contraves in Zurich, and in charge of our product range of ground-based air defence systems. He determines which products will be offered for which requirements, and is also responsible for developing the company's strategic product portfolio. A colonel in the Swiss Air Force, he commands one the Swiss Army's two active air defence combat groups, giving him an in-depth knowledge of the subject. During his more than twenty years with Oerlikon Contraves, his invaluable hands-on experience has repeatedly given crucial impetus to the development of new products.