August 23, 2010: The U.S. Department of Defense is equipping four UH-60 transport helicopters in Afghanistan with  HALTT (Helicopter Alert and Threat Termination), an acoustic detection system to tell the pilot what direction ground fire is coming from. This makes it easier for the pilot to evade the fire, and avoid getting shot down, or suffering more damage. HALTT is already being configured for other helicopter types, because the system performed very well in tests, and is expected to do well in its combat zone test.

Basically, HALTT alerts the pilot that someone is shooting at his helicopter, even if not bullets have hit the aircraft yet. This is the most typical situation, because you cannot hear the ground fire, nor can you see it unless the enemy is using tracer rounds (and someone on board is looking in the right direction). So HALTT alerts the pilot that fire is coming from a specific direction, allowing the helicopter to quickly move away from the source of the fire. If the helicopter is carrying weapons, HALTT allows a much faster attack on the source of the ground fire.

Acoustic gunfire (sniper) detectors, which have been in the field for a decade, have had increasing success. HALTT is based on this technology. Thousands of sniper detectors have been shipped to Iraq and Afghanistan, where they have been increasingly useful. Sniper detection systems provide directional information about where the snipers are. Several generations of these systems have showed up over the last decade. The usefulness of these anti-sniper systems has increased as the manufacturers have decreased the number of false alarms, and improved the user interface. There are other reasons for all this progress, including major advances in computing power, sensor quality and software development. One of the latest, and most useful, improvements is providing nearly instant, and easy to comprehend, location info on the sniper.

British, American, French and Israeli manufacturers have produced most of these systems, which are also sold to police organizations. The systems have varied greatly in capabilities, and price. Some have cost over $200,000, while the more popular ones, like the Boomerang, cost about $5,000. HALTT is based on the Boomerang system.

Some systems were equipped with a camera, that can give troops inside an armored vehicle, or in a distant location, a picture, or video, of where the shot came from. One U.S. firm, iRobot, which makes the most widely used combat robot, the PackBot, developed a similar system. Called REDOWL (for Robot Enhanced Detection Outpost with Lasers), it mounted a 2.6 kg/5.5 pound package on a PackBot that contains an infrared (heat sensing) video camera, laser rangefinder and acoustic gunfire detector. When the device is turned on, the camera and laser will point to any gunshot in the area. This makes it a lot easier for nearby troops to take out the sniper. REDOWL can also be mounted on vehicles, or anywhere, for that matter. In tests, REDOWL has been right 94 percent of the time. Some developers suggested equipping REDOWL with a machine-gun in place of the laser. But the U.S. Army wasn't ready for an armed robot that will identify and fire on targets all by itself. A similar system, Pilar had an advantage over REDOWL with its longer range. Pilar could find snipers who are as far as a thousand meters out, about twice the range of the iRobot system. But systems like Pilar cost $65,000 each and were considered too expensive for wide use. Israel has produced a similar system, SADS (Small Arms Detection System), that also has a thousand meter range.

Then there is the U.S. Boomerang system. Developed in a few months, in response to a Department of Defense request for an affordable acoustic sniper detector, it entered service within two years. Boomerang is mounted on vehicles, has been around for five years, and costs about $5,000 each. Boomerang has been effective enough to get orders for over 10,000 units, and lots of use from the troops who have it.