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via missile, or ground aided seeker. Radar weapons must detect, acquire, track, launch and guide (or fire a
ballistic solution), and assess damage. Radar systems have trouble with ground clutter. To pick out targets
from ground clutter, radar systems can detect movement though the use of moving target indicator, Doppler
(continuous wave radar), or Pulse Doppler. Modern radar systems can track the movement of the aircraft,
while some systems also detect the movement of rotor blades. A few older radar systems had blind speeds
(called a Doppler notch), where they could not detect an aircraft flying a specific speed towards or away
from the radar. Modern radar systems cancel blind speeds. Radar systems can be detected, avoided,
decoyed, jammed, and destroyed by direct and indirect fires (self, artillery, and antiradiation missiles).
(2) Infrared. All IR direct threat weapons require LOS to be established prior to launch and the in-flight
missile must maintain LOS with the target until impact (or detonation of the proximity fuse). IR missiles
require the operator to visually detect the target and energize the seeker before the sensor acquires the
target. The operator must track the target with the seeker caged to the LOS until it is determined that the
seeker is tracking the target and not any background objects (natural or man made objects to include
vehicles, the sun, or reflected energy of the sun off clouds, etc.). The IR sensor is also susceptible to
atmospheric conditions (haze, humidity), the signature of the aircraft and its background, flares, decoys,
and jamming. Generally IR systems are--
l   Difficult to detect prior to launch (passive sensor).
l   Difficult to predict where they may be located (portability).
l   Difficult to respond to (short time of flight after launched).
l   Difficult to hard kill (requires shooting at an in-flight missile).
(3) Laser and directed energy weapons. Laser/DEW weapons really fit two distinct categories--laser
guided or aided weapons and pure laser/DEW weapons. Laser guided, or aided weapons, are those who use
FM 1-113 Appendix G
G-3
the laser to perform ranging, tracking, or guiding functions for conventional explosive missiles or
projectiles. Pure laser/DEW weapons use Laser and other forms of DEW to inflict damage to the aircraft or
its sensors, including the eyes of the aircrews. Pure laser/DEW weapons are not required to burn a hole in
the target to destroy it (although these weapons are reaching that capability). Simply igniting fuel vapor
near vents or burning through fuel lines are effective, as well as glazing the cockpit glass so the aircrew
cannot see out. Inherently, laser/DEW weapons are short duration, hard to detect, extremely hard to decoy
or jam, and hard to kill. Fortunately they must rely upon LOS, certain atmospheric conditions, and are
somewhat short range, at present.
(4) Optical/electro-optical. Optical/EO sensors are used as either the primary or secondary sensor for all
weapon systems. Although they rely upon LOS, they are, with very few exceptions, completely passive.
They are limited by human eyes, atmospheric conditions, distance, operator movement, and in many cases,
by darkness. The optical/EO sensors are most difficult to detect and seldom can be decoyed; however, they
can be jammed by obscurants, and when located, can be hard killed.
G-3. AIRCRAFT SURVIVABILITY EQUIPMENT SYSTEMS
a. Aircraft Signature Reduction. All cargo and utility helicopters are painted with nonreflecting IR absorbing
paint. UH-60 and EH-60 aircraft are equipped with HIRSS, which reduces the IR signature by suppressing hot
exhaust gases. HIRSS aids the effectiveness of the AN/ALQ-144A IR missile jammer. CH-47 aircraft do not
presently have exhaust suppression. The CH-47 aircraft are protected from IR missiles by the combination of the
AN/ALQ-156 countermeasures set and the M-130 flare dispenser. The radar and IR signature of utility and cargo
helicopters is least when viewed from the front. The maximum IR signature is from the rear quadrants, whereas
the maximum radar signature is from the side aspects. The aircrews have the ability of decreasing the signature
exposed to threats by changing the aspect of the aircraft. This is least effective in the CH-47 aircraft.
b. Aircraft Survivability Equipment Suites.
(1) EH-60 aircraft survivability equipment suite capabilities. The EH-60 ASE suite provides for PW radar
and CW radar signal detection, CW radar jamming, and decoying for radar directed threats. Additionally
the ASE suite provides omnidirectional IR jamming and decoying for IR directed threats. The aircraft
signature reduction capabilities includes both nonreflective IR absorbing paint and HIRSS, which
　
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