Tuesday, August 17, 2010

High-Flying Apache Helicopter Pilots Take Aim with Arrowhead

For much of the post-WWII era, US helicopter pilots have been trained to fly “low and fast.” This was based on combat experience in Korea and Vietnam. However, in the urban environments of Iraq and Afghanistan, flying low and fast has made helicopters more vulnerable to a number of threats: terrain, wires/powerlines, rocket propelled grenades, small arms fire, and MANPADS.

Enter the Arrowhead system. Arrowhead is an electro-optical and fire control system that AH-64 Apache helicopter pilots use for combat targeting of their Hellfire missiles and other weapons, as well as flying in day, night, or bad weather missions. The system enables pilots to target accurately at high altitudes.

Flying Low and Fast

"Low and fast” has been the mantra of US helicopter pilots for much of the post-war era. Flying low and fast enabled pilots to avoid radar-guided missiles and anti-aircraft artillery. Low-level flying also improved the survivability of the crew when something went wrong. If the helicopter had a mechanical problem or was hit by enemy fire, the pilot could ditch the helicopter more easily at a low altitude.

However, flying low and fast has made helicopters more vulnerable to a number of urban combat threats: terrain, wires/powerlines, rocket-propelled grenades, small arms fire, and MANPADS.

Losses suffered early on in Operation Iraqi Freedom (OIF) convinced the US Army that flying low and fast was contributing to high helicopter losses. For example, in the first 3 months of OIF, 12 US Army helicopters were shot down, all at 400 feet or below.

Instead, maintaining a high altitude allows pilots to avoid many of the urban combat threats. Staying above 500 feet enables pilots to avoid wires and power lines; above 1,500 feet, RPGs; and above 3,000 feet, small arms and light machine gun fire.

Fighting in an urban environment increases the need to carry out nighttime operations because insurgents often use nighttime maneuver for cover. Also, urban combat can involve operating in smokey environments caused by the enemy purposively setting fires to provide a smoke-filled veil or as a result of fires started in buildings from weapons.

As a result, the US military realized that helicopter pilots need the ability to see and target at a distance, through smoke and obscurants, and at night.

Apaches need arrowheads

To provide these capabilities, the Army turned to Lockheed Martin to develop the Arrowhead sensor system. Arrowhead – also known as the Modernized Target Acquisition Designation Sight/ Pilot Night Vision System (M-TADS/PNVS) – is an electro-optical and fire control system that the Boeing-built AH-64 Apache helicopter pilots use for combat targeting of their Hellfire missiles and other weapons, as well as flying in day, night, or bad weather missions. The system enables pilots to target accurately at high altitudes. Check out this Discovery Channel video of the Apache with the Arrowhead system in action.

The Arrowhead system has two turrets [pdf]. The lower turret contains the targeting system, with a forward-looking infrared (FLIR) sensor that can see through haze and smoke and at night.
The FLIR sensor has three fields-of-view, a multi-target tracker, multiple-code laser spot tracking, and internal boresight. A charge-coupled device camera enables day TV viewing. Arrowhead’s electro-optics replace the older version TADS/PNVS direct-view optics with a TADS electronic display and control (TEDAC) unit.

The upper turret houses the pilot night vision system, which provides a long-wave, high-definition FLIR sensor with 52-degree wide field of view optics. The system’s processing algorithms give pilots sufficient resolution to avoid obstacles (including wires and trees) during low-level flight and at night.

Digital data from the FLIR sensor is displayed in the cockpit and on the pilot’s helmet-mounted display, providing high-resolution images. Arrowhead also has an image-intensified TV camera to aid aircraft pilotage in thermal environments and urban scenarios. The TV camera enables the pilots to see ground tracers, laser points and other signals from the ground. The system’s software combines imagery from the TV and the FLIR sensor into one multi-spectral image for the pilot and crew.

Particularly relevant for high-altitude flight is the Arrowhead system’s range for identifying targets. The system provides aircrews with a clear FLIR image at ranges greater than 5 miles. This range enables helicopter pilots to maintain an altitude above 2,500 feet and still provide firepower support to US soldiers on the ground.

Arrowhead also helps Apache pilots cope with brownout, which is reduced visibility caused by blinding sand and dust clouds churned up by the helicopter’s rotors. The US Army has lost 27 helicopters in brownout accidents since 2002, including the October 2009 crash of a special operations H-47 Chinook helicopter, which hit a hidden obstacle and crashed with 10 lives lost.

Commenting on the ability of Arrowhead to aid Apache pilots in brownout situations, Col. Mark Hayes, capabilities manager for the US Army Training and Doctrine Command, told the Army Times in April 2008:

“With MTADS [Arrowhead] we have far fewer challenges with obscurants than we had because the acuity of the system is so good. For example, it will see through rain. It will see through light fog. It will see through a certain amount of smoke.”

Lockheed Martin rolled out the first Arrowhead system to the US Army in May 2005 and completed integration on the first Apache helicopters in June 2005. The Arrowhead system is provided as original equipment on new Apache helicopters and as retrofit kits that upgrade the older version TADS/PNVS systems.

Over 850 Arrowhead systems will have been delivered with the completion of the Lot 6 contract, which extends production through December 2011. For details on the Lot 1-6 contracts, check out the Contracts and Key Events section below.

To read more, click here.

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