Counter-rocket, artillery and mortar

Template:TOC-right Counter-mortar, artillery and rocket (C-RAM) is the U.S. Army term for a new defensive technique. It is a new mission for the Air Defense Artillery branch. While the U.S. has operational C-RAM in Iraq and Afghanistan, and at the highly realistic Joint Readiness Training Center, Israel is actively developing C-RAM to protect urban areas, which it sees as a having different constraints than the U.S. military system. Denmark and a Swiss/German team are also building C-RAM. Britain is using the current U.S. system.

Previous "counter-artillery" systems, such as the AN/TPQ-36, tracked a shell back to its point of origin, but relied on counterbattery methods to prevent the next attack: counterbattery gives the coordinates to one's own artillery, which fires on the enemy point of origin attempting to destroy the weapons there. Counterartillery sensors only detect, and counterbattery is preemptive deadly force. C-RAM, instead, is active defense: it intercepts and destroys the rocket, artillery shell, or mortar shell in midair. the C-RAM system proper does not attack the point of origin.

A concept of "seven pillars" was drawn up by a 2004 NATO 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 pillars are:

• shape
• sense
• warn
• intercept
• respond
• command and control
• protect

Only four of those pillars are truly part of "active defense", which is what differentiates C-RAM from counterartillery detection & warning, counterbattery, and passive protection. The U.S.Army provides more detail the pillars, but not all of the "pillars" are truly active defenses: .

Active defense	Preemptive	Passive defense
Command and control direct active defense, passive defense and response	Respond "application of lethal fires before or after RAM attacks"	shape "actions taken to deny the enemy's use of tactically advantageous terrain or to channel enemy forces into areas where they can be observed."
sense		protect:actions taken to harden sites or disperse assets to mitigate the effects of RAM attacks.
warn (cue C-RAM interceptor)		warn threatened troops to take cover; friendly aircraft to stay out of engagement volume
intercept

Counterbattery methods are inappropriate for situations where the threat is from guerillas firing unguided rockets or mortars from urban areas. Rockets, in such situations, may be launched from single-use launchers fired by a timer, so there is no equipment to destroy. More importantly, even if there were a mortar, counterbattery into an urban area would be apt to cause unacceptable civilian casualties. If the counterbattery weapon used antipersonnel or "dual-purpose" cluster submunitions, the percentage of submunitions that do not detonate, but still are dangerous, effectively creates an antipersonnel minefield. There is a international initiative to ban antipersonnel mines, so such methods become even more unattractive.

While there are anti-ballistic missiles and surface-to-air missiles, they are designed to engage much larger targets than artillery, light rockets, and mortars; a typical mortar shell is 81mm in diameter and approximately 240mm long. Katyusha and GRAD rockets, as well as locally made variants, are larger, on the order of 150mm diameter and 2 meter length.

Mortar shells have successfully been shot down at Balad Air Base in Iraq. One article from mid-2008, without explicitly naming systems, speaks of knocking down the 100th enemy round.

Command and control

For the U.S., the Forward Area Air Defense (FAAD) is considered the core of the initial C-RAM systems. FAAD interfaces with multiple sensors and information feeds in the Air Defense Artillery cell at Brigade Combat Team level.

Sense

Several U.S. systems provide C-RAM sensing, starting with the AN/TPQ-46 Light-Weight Counter-Mortar Radar, which gives short-range but 360 degree coverage. AN/TPQ-36 and AN/TPQ-37 radars have, respectively, medium and long range, but are directional.

While not all the details have been released, it is likely that electro-optical sensors give warning; there is an electro-optical as well as radar fire control sensor on the current "Centurion" Land-Based Phalanx Weapon System (LPWS) intercepting autocannon. Another potential sensor is the Unattended Transient Acoustic MASINT Sensor (UTAMS)

Warn

There is more than one kind of warning that must be sent out. Obviously, soldiers in the potential impact area need to be directed to take cover. Friendly aircraft also need to know about both the incoming threat projectiles and the fact that C-RAM is about to engage it, so they do not fly into the trajectory of either.

In the initial U.S. implementation, the Wireless Audio Visual Emergency System (WAVES) receives warning from sensors and alerts soldiers threatened by the weapons.

Friendly aircraft are tracked with the AN/MPQ-64 Sentinel radar, which has a good deal of commonality with the AN/TPQ-36. The Sentinel feeds into FAAD.

Intercept

There is very rapid development. Initial systems use 20mm autocannon. A 35mm autocannon and a laser system are in the demonstration phase.

Operational

Operational systems intercept C-RAM autocannon, although lasers have been demonstrated against the threat. Israel has a small missile in development.

In use in Iraq and Afghanistan is the Centurion LPWS, a modification of the Phalanx close-in weapons system, a 20mm autocannon originally deployed to protect ships against sea-skimming anti-shipping missiles (ASM). Phalanx was effective against older, subsonic missiles, but is being replaced against the increased threat of high-performance missiles such as the Russian Moskit.

LPWS has two radar and a forward-looking infrared sensor. The first radar, which searches for the target after being cued, is a Ku-band with Moving Target Indicator. The fire control radar is also Ku-band, using pulse Doppler techniques. Phalanx always used two radars: it followed the target with one, and tracked its own stream of shells with the other; its fire control computer moved the gunfire to intercept the target. The FLIR sensor is new; it also has a recorder that allows review of engagements. Raytheon has proposed adding a coaxial high-energy laser.

Land warfare RAM, however, while smaller than ASM, are, in some respects, easier to track. They are on a ballistic trajectory that can be predicted, against the clean background of the sky. In contrast, a sea-skimming missile will fly just above the water, taking advantage of the radar clutter of waves, and also often maneuvers just before impact, guiding all the way into the target.

Near term

Rheinmetall is working on a dual 35mm autocannon, with greater range than the 20mm Phalanx. This will be a variant of its Skyshield anti-aircraft gun system.

Moderate term

Israel has raised concerns about the existing and near-term systems, which it believes are too optimized for point defense of high-value targets to be useful for its need for urban area protection. Alternatives here include both an Israeli wide area guided missile interceptor system called Iron Dome, and the joint U.S.-Israel Mobile Tactical High Energy Laser (MTHEL; now called Nautilus).

Israel continues to improve a multilayered missile defense system that also would have capability against larger, longer-range unguided rockets as well. Such rockets would be engaged by the lower-altitude systems, such as MIM-104 Patriot PAC-3 in the atmosphere, and still would use point defense. THAAD, Arrow-2, and a possible land adaptation of RIM-161 Standard SM-3 would remain focused on ballistic missiles.

Proximity kill missile

Iron Dome uses a missile called Tamir, with autonomous control to have it engage only those incoming Palestinian fired Qasam improvised rocket and 107mm and 122mm Katyusha and Grad rockets, deployed by Hezbollah, as well as 155mm artillery shells, from points of origin up to 70 km away. Iron Dome target acquisition and threat assessment will use the Elta Advanced Artillery Radar (AAR).

Command and control come from a Battle Management & Weapon Control (BMC), which, after identifying projectiles presenting a threat, will command the best-placed launcher to fire a Tamir. BMC has an uplink to the Tamir and guides into proximity of the target; Tamir is not hit-to-kill as are the gun and laser systems. A constraint of targeting is that the engagement should take place over a neutral area, where there is little to suffer collateral damage, as opposed to avoiding it with self-destructing munitions in Centurion.

Laser system

A U.S. development system called the Tactical High Energy Laser has demonstrated the ability, since 2000, to shoot down RAM. Funding was stopped in 2006, due to budget cuts and concerns that the range was too short, requiring a larger number of interceptors. Northrop Grumman continued development using internal funds, working on a "relocateable" version of THEL. Its radar is already operational in Israel, providing early warning from Palestinian attacks on the the city of Shderot.

In 2006, Northrop Grumman announced the Skyguard Laser Based Counter-MANPADS / C-RAM System, not to be confused with the Oerlikon-Rheinmetall gun-based system. Note that it is not only a C-RAM system, but intended to have a role in protecting airfield landings and takeoffs from man-portable air defense systems, or shoulder-fired surface-to-air missiles that are a distinct concern in the civilian air transport industry. It could engage MANPADS targets at a range of roughly 20 kilometers (12.4 miles), but a reduced C-RAM range of 5 kilometers (3.1 miles). In October 2006, Northrop Grumman received a 18-month U.S. Department of Homeland Security contract to evaluate effectiveness against threat to airliners.