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sets, and infrared missile warning systems.
(4) Step 4. Jamming and decoying (electronic attack). When aircrews must stay on station despite
warnings, there is a requirement for countermeasures capable of jamming, and/or decoying the fire control
or guidance systems of threat weapons. Chaff, flares, and radar and IR jammers provide this type of
protection.
(5) Step 5. Aircraft hardening (vulnerability reduction). This step provides for ballistic tolerance,
redundant critical flight systems, and crashworthy features, to assist in minimizing the damage to an aircraft
after it has been hit.
G-2. THREAT CONSIDERATIONS
This section is not designed to be system specific in nature, rather to provide a general knowledge of threat systems,
which can be applied to specific threats on a case by case basis.
a. Threat Engagement Sequence. All weapon systems must complete a series of events, called an engagement
sequence, to actually have an effect on the target (aircraft). Missing any step in the engagement sequence forces
the threat engagement sequence to be started over again. Weapon systems sensors must--
l   Detect.
l   Acquire.
l   Track.
l   Launch and guide (or fire and ballistics).
l   Assess damage.
b. Example Threat System. Five elements required to a compute an AAA fire control solution are range, azimuth,
elevation, velocity, and time of flight. If one of the fire elements is incorrect, the AAA system will not hit the
target.
c. Target Acquisition. The threat must detect, acquire, track (establish fire control solution), and fire at the
aircraft. The time of flight of the projectile must be determined. The threat must predict where the aircraft target
will be (within a few meters) as the ordinance travels to a point in space and time.
d. Threat Avoidance. Tactics, signature reduction, warning, jamming and decoys are the tools available to
preclude a successful threat engagement. If hit, you may have to rely on aircraft hardening.
e. Detection, Acquisition, and Tracking. The difference between detection and acquisition, versus tracking is
FM 1-113 Appendix G
G-2
very important. In detection and acquisition, the threat weapon system does not have enough refined data to
facilitate firing at the aircraft. The threat weapon system must track the aircraft long enough to acquire range,
azimuth, elevation, and velocity, to determine the time and position of firing. Indications of search or acquisition
activity may provide the aircrew time to initiate a response. Tracking indications alert the aircrew to an immediate
action requirement, such as masking, employing ASE decoys, or executing evasive maneuvers.
f. Engagement Envelope. All threat systems are confined by physics. Each threat system has a minimum and
maximum effective altitude and range. These numbers are computed against a cooperative engagement
(nonmaneuvering aircraft, blue sky background, flat terrain, steady velocity, etc.). The effective envelope for a
threat system is based upon a 50 percentile. That is, at the maximum (or minimum) effective range (or altitude),
the weapon system is able to hit the target one out of two times. As the target progresses further into the threat
envelope, the probability of a first shot kill increases. As the target progresses further outside the threat envelope,
the probability of being hit decreases, until the target has reached a point where it is impossible to be hit.
g. Decreasing the Probability of Hit. The aircrew has the ability to make the engagement more difficult for the
threat. A stationary target allows the threat to adjust each shot from the previous shot, until it hits the aircraft. A
moving, constant velocity target provides a more difficult engagement procedure. A prediction can be made from
the previous shot and adjustments imposed to enhance accuracy. The most difficult engagement is the moving
target that varies range, altitude, elevation, and velocity. This makes prediction nearly impossible, since four
factors are changing at differing rates.
h. Threat Weapon Sensors. There are generally four major types of threat weapon sensors. These may be
man-portable or transported by land, sea, or aerial platforms. It is important to determine the actual sensor type,
and guidance package, for each threat and understand their inherent capabilities and limitations. (For in-depth
information concerning particular threat systems, contact your unit electronic warfare officer or tactical operations
officer.) The four major types of threat weapon sensors are radar, IR, laser and DEW, and optical/EO.
(1) Radar. Direct threat radar weapons require LOS to hit the target. Direct threat radar weapons are either
fire controlled AAA or for missile systems command, semiactive radar homing, active radar homing, track
　
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