Saab’s RBS15 Mk3 anti-ship missile

The archipelago of the Baltic Sea is the largest in the world, and with its tens of thousands of islands and skerries it is both beautiful and awe-inspiring. But from a military perspective, it is also an extremely tough and demanding environment. Its narrow waters and closely spaced islands make it difficult for vessels to move freely and operate in the area. The highly cluttered environment provides cover to friendly units and enemy vessels alike, necessitating the use of systems that are robust, nimble and intelligent. With its naval roots in the shallow waters of the Baltic archipelago, Saab is positioned as a world leader in products and solutions for the littoral environment.

As the nature of conflicts change, this and similar environments have become of greater strategic importance and brought Saab's products into the forefront. Saab's latest anti-ship missile, the RBS15 Mk3, is uniquely adapted to the challenging environment of the littorals; able to engage targets with full force, over long distances and in a cluttered battlespace.

Potential threats loom large in the shallow and narrow waters of the Baltic archipelago. This environment and others like it, together with geopolitical changes unseen for a generation, are sparking the production of a new generation of warships adapted to the littoral environment. These vessels are designed to operate in the confined spaces and narrow passageways of the archipelago, able to pursue and evade enemies with equal ease. Vessels, sensors and weapons must be finely tuned and adapted to this environment where old big-navy doctrines no longer apply. Here one must be nimble and cunning, able to use the environment to one's own advantage while turning it against the enemy.

Track and defeat hidden targets

Targets can easily hide among the thousands of islands and skerries that litter the coasts of the Baltic Sea. Here weapons and sensors must not only be able to discriminate between enemy ships and islands, but between targets, non-targets and false targets as well. The navies of Sweden and Finland have trained since their inception to act and fight in these waters. Their hard-earned experience is seeing renewed importance as the world's focus is shifted towards the cluttered environment of the littorals.

In the busy waters of the Baltic, enemy ships can appear virtually out of nowhere and at a moment's notice. Defensive systems must therefore be ready to act quickly and at any time, irrespective of the prevailing weather. Potential targets can be moving at sea, close to shore or stationary on land. This requires that missile systems be robust enough to offer full tactical availability in all weather. They must also have the flexibility to be able to attack all types of targets and the range to strike at them, even from cover. Due to the vast area and low number of units at the disposal of these Nordic countries, they must have weapons that can do more; that are robust yet adaptable and with a profound stand-off range.

Communication is also a key. The Nordic countries were quick to adopt the latest technological advancements like net-centric warfare. The use of a tactical data link allows units to share target information and to employ weapons that can engage from beyond the horizon.

The RBS15 Mk3 surface-to-surface missile from Saab is designed to operate in the extremely challenging environment of the littorals. It is designed to go further, strike harder and smarter at targets large or small, in all weather conditions.

The archipelago – the toughest environment there is

The RBS15 Mk3 is designed for operation in the cluttered littoral environment of the Swedish archipelago. One of the many important features of the RBS15 is its ability to fly at sea-skimming altitude. The onboard altimeter continuously monitors the height above the waves and minimizes the missile's flight altitude. Flying at a minimum altitude along the entire trajectory allows the missile to approach the target undetected, remaining below the radar horizon until the very last minute. Especially in a cluttered environment like the Baltic archipelago, where other potentially undetected enemy vessels may be hiding along the flight path, it becomes important to minimize the probability of detection by having a sea-skimming approach from launch to impact.

By reducing the visibility of the missile in the electromagnetic spectrum, the missile can get even closer to the target before detection. Though as naval ships employ radars with ever increasing fidelity and resolution, massive investments in reduced RCS and stealth features will fail to pay dividends. We're already seeing this shift in the air theatre and the naval scenario is no different. Instead, managing the detection by avoiding hard-kill and soft-kill measures will become increasingly important. The RBS15 Mk3 penetrates enemy defenses by maintaining a sea-skimming profile and employing evasive maneuvers and advanced electronic counter-countermeasures (ECCM).

With today's technology we can control many aspects of the battlefield. Unfortunately, the weather is still not one of them. Since a battle might take place at any time, in any weather and in any condition, missile systems cannot be dependent on fair weather. Over long distances, the weather may vary greatly so a missile designed for use in the littoral environment, like the RBS15 Mk3, needs to be insensitive to changing weather conditions. The missile's target seeker needs to be capable enough to find its target even in adverse weather. For this reason, an active radar target seeker is necessary, as it is not negatively affected by the atmosphere or the water in it, like infra-red target seekers.

The need for autonomous weapons

The ability to deny the availability of GPS and data links within a conflict area is becoming easier and easier to obtain. Today, relatively unsophisticated adversaries can obtain and operate basic Electronic Warfare (EW) equipment that presents an operational threat to units relying on GPS and data-links. Some countries have already launched programs aimed at finding technologies that can supplement GPS for that very reason. Against a sophisticated adversary, weapons will need to be able to operate autonomously and be insensitive to powerful EW that disables or disrupts communication channels. Another reason to use an active radar target seeker is the size of the target seeker area. Since the radar is not dampened by atmospheric water, its range is much greater than for example, an IR sensor. This allows for detection and acquisition of targets moving at high speed at long ranges, without requiring target position updates via a data link or relying on GPS positioning.

Approaching and finding a target is just the first step, penetrating its defenses is where things get difficult. Thankfully, the RBS15 Mk3 is well equipped with measures to counter both soft-kill and hard-kill systems that may be employed by the target.

The missile's active radar target seeker features a high power monopulse with frequency agility and a jittered Pulse-Repetition Frequency (PRF). These and other features allow it to counter all existing forms of active and passive electronic countermeasures. In the unlikely event that the target seeker becomes jammed, RBS15 Mk3 has a Home-On-Jam feature that effectively turns it into an anti-radiation missile. This places the adversary in a difficult position; forced to either stop jamming and see the missile find its target, or continue jamming and become the target.

The target seeker also has a unique target discrimination capability thanks to the high resolution in both bearing and range which also contributes to insensitivity to chaff, decoys and jammers. Additionally, the target seeker's behavior is software controlled. This allows the RBS15 to easily adapt to new threats as they emerge and for new features to be added through software updates.

The RBS15 Mk3 penetrates the final layers of defense by making itself difficult to detect and difficult to shoot down. A reduced signature together with a silent approach from below the target's radar horizon delays detection until the very last moment. Flying low also reduces the effectiveness of the tracking sensors and the proximity sensors of the munitions fired against the incoming missile. Even if the target's defenses are capable and effective, they can be saturated by firing multiple missiles preprogrammed with a simultaneous time on target. The RBS15 Mk3's superb navigational systems allow multiple missiles to arrive at the target at the same time, even when fired from multiple platforms and with different trajectories and approach angles.

Multiple 3D waypoints for utilization of the missile´s potential

To be a reliable and effective weapon in a littoral environment, especially one as cluttered as the archipelagos of the Baltic Sea, a missile like the RBS15 Mk3 must be very maneuverable. Thankfully the RBS15 Mk3 is designed to operate in these waters and features great maneuverability and a flexible trajectory with multiple 3D waypoints that allows the operator to utilize the missile's full potential. From over 200 km away the missile can quickly and easily be programmed to fly above or around the many islands in the littoral waters and to approach the target from any direction.

In the cramped and cluttered waters of the Baltic archipelagos, the threat of attack from the world-leading RBS15 Mk3 presents a clear and present danger to any would-be aggressor. In this highly strategic arena a small number of highly capable and well adapted ships, sensors and weapons work in unison to allow these small nations to protect their sovereignty and remain at peace.

Björn Bengtsson,
Director of Business Management ASM at Saab´s Business Unit Missile Systems.

Michael Höglund,
Vice President of Marketing & Sales at Saab´s Business Unit Missile Systems.