Tuesday, December 21, 2010

Apache Helicopter Pilots Take Aim with Arrowhead

SOURCE DEFENSE INDUSTRY DAILY- 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 shoulder-fired missiles.
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 also provides accurate targeting at high altitudes, a practice that also has its drawbacks. This free-to-view Spotlight article covers the Arrowhead’s characteristics, components, contacts, consequences, and contracts…
Challenges of Urban Warfare
AH-64D Longbow Over Road
Flying Low and Fast
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“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.
The Arrowhead Advantage
Arrowhead Sensors
Apaches need arrowheads
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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 is provided as original equipment on new Apache helicopters, or as retrofit kits that upgrade the older version TADS/PNVS systems. 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. Over 1,000 Arrowhead systems will have been delivered with the completion of the Lot 7 contract, which extends production through April 2013. For details on the Lot 1-7 contracts, check out the Contracts and Key Events section below.
The Arrowhead system has 2 turrets [PDF]. The lower turret contains the targeting system, with day and night sensor assemblies. The day sensor assembly [PDF], which is undergoing modernization, incorporates a laser rangefinder designator, TV sensor, and laser spot tracker components.
The night sensor assembly includes the 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. 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.”
VNsight and Pathfinder
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To provide enhanced night vision capabilities, Lockheed Martin offers the VNsight [pdf] add-on for both the Arrowhead system and the Pathfinder system, which is a version of the Arrowhead system adapted for cargo and utility helicopters. VNsight provides enhanced visible light/ near infrared sensor capabilities that complement the long-wave infrared wavelength of the FLIR sensor.
Using the composite of VNsight and FLIR imagery, pilots can see cultural and military lighting (lasers, markers, beacons, tracer rounds, etc.) registered with the thermal image over the 30 by 52 degree field of view of the sensor. This improves situational awareness in low-light conditions and situations where existing light sources cannot be imaged by the FLIR. The capability to image all light sources with the VNsight sensor allows pilots to see laser pointers used to target laser-guided munitions.
As noted, the Pathfinder [pdf] system is a version of Arrowhead adapted for cargo and utility helicopters. The high-resolution FLIR imagery is projected onto the visor of the pilot’s helmet while the turreted sensor assembly is slewed to the helmet and is coordinated with the pilot’s head movements.
The Pathfinder system displays flight information on the helmet visor so that the pilot can maintain a head-up, eyes-out posture when operating in low visibility conditions. This approach maximizes the pilot’s unobstructed visibility (invisible cockpit), facilitates detection and avoidance of obstacles at lower altitudes and higher airspeeds; and provides the ability to identify and react to threats.
The Pathfinder turret mounts on the helicopter’s chin using a kit consisting of 3 line-replaceable modules. Eleven of the 14 line-replaceable modules are common with the Arrowhead. This creates synergy with the established Arrowhead production line and performance based logistics.
Lockheed Martin notes that Pathfinder is currently the only IR sensor system designed and developed specifically to support terrain flight (low level, contour, and nap-of-the-earth) and terminal operations in unimproved landing areas during reduced visibility conditions.
High-Flying Drawbacks
AH-64 Apache Flying High
AH-64 Apache Flying High
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The Arrowhead sensor enables Apache helicopters to maintain high altitudes, which allow crews to remain out of range of a number of urban combat threats.
However, high-altitude flight doesn’t come without problems. In a USMC Command and Staff College paper, Capt. A. C. Schilleci said that high-altitude flight prevents pilots from feeling and absorbing the intangibles of urban ground combat.
Also, he noted that if helicopter pilot training and experience focuses on high-altitude attack enabled by Arrowhead in an urban environment, the pilots might lose the ability to be effective in large-scale anti-armor missions, which could become the Achilles heel for attack aviation:
“The attack helicopter community must combine the fundamental tank killing successes achieved in Operation Desert Storm with the insurgent exploitability learned and gained in OIF/OEF with the M-TADS. Once this evolution is completely implemented and properly standardized throughout Army attack aviation, the ability to surgically strike our future armored enemies becomes limitless.”
Col. Jim Slife, a USAF special ops pilot, in a 2007 Armed Forces Journal article identifies a number of other high-altitude flight issues:
  • Some helicopter missions, such as close air support (CAS), require low-altitude flight. With training, pilots could fly CAS missions from altitudes above 3,000 feet. This altitude would eliminate the environmental obstacles, as well as threats from small arms, light machine guns, rocket-propelled grenades, and the scourge of helicopter pilots, MANPADS.
  • Flying at high altitudes can make it more difficult for helicopters to maintain visual contact and stay in formation, particularly if there is heavy cloud cover.
  • Many helicopter countermeasure systems are optimize for operation at low altitudes and may not provide cover at high altitudes. Existing countermeasure system might have to be modified.
  • A helicopter’s lifting performance is reduced with altitude. Helicopter engines run hotter at higher altitudes, which reduces performance. Also, the aerodynamic performance of rotor systems decreases in thinner air.
  • At high altitudes, there is a blind spot under the helicopter that can’t be visually scanned. This makes the helicopter’s underbelly vulnerable to attack.
These disadvantages are obviously not a problem with the Arrowhead system per se, but an issue for high-altitude helicopter flight in general.
But the advantages of high-altitude flight, reducing the number of helicopters and crewmembers lost in combat, far outweigh the problems. And the Arrowhead system, with its targeting range and night time/bad weather viewing capabilities, enable pilots to opt for high-altitude and/or night flying, if the situation requires it.
Key Contacts as of July 2010
  • Al Winn, vice president of Apache Programs, Boeing; email: albert.l.winn at boeing.com
  • Col. Shane Openshaw, Apache project manager, US Army PEO Aviation; phone: 256-313-4200; email: shane.openshaw at us.army.mil
  • Rich Tyler, Apache deputy project manager, US Army PEO Aviation; phone: 256-313-4201; james.richard.tyler at us.army.mil
  • Lt. Col. Lohn Vannoy, Apache Project Office, product manager for sensors, US Army PEO Aviation; phone: 256-313-4310; email: john.vannoy at us.army.mil
Contracts and Key Events
Unless otherwise noted, Arrowhead contracts are awarded to Lockheed Martin Missiles and Fire Control in Orlando, FL, by the US Army Aviation and Missile Command in Redstone Arsenal, AL.

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