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Part N
LIMITED VISIBILITY TECHNIQUES
1. General. The infantry fights at night to take advantage of limited visibility. The use of NVDs and scanning techniques aids the infantryman in operating during all limited visibility conditions. This section provides techniques for improving and maintaining night vision, and techniques for attacks during limited visibility.
2. Night Vision. Darkness affects the senses of sight, hearing, and smell. Sharpening these senses requires training. Soldiers must know how their eyes function at night to best use them.
a. Night Vision Scanning. Dark adaptation is only the first step toward making the greatest use of night vision. Scanning enables soldiers to overcome many of the physiological limitations of their eyes(Figure 2-96). It can also reduce confusing visual illusions. This technique involves looking from right to left or left to right using a slow, regular scanning movement . At night, it is essential to avoid looking directly at a faintly visible object when trying to confirm its presence.
Figure 2-96. Typical Scanning Pattern.
b. Use of Off-Center Vision. The technique of viewing an object using central vision is ineffective at night. This is due to the night blind spot that exists during low illumination. Soldiers must learn to use off-center vision. This technique requires viewing an object by looking 10 degrees above, below, or to either side of it rather than directly at it( Figure 2-97).
Figure 2-97. Off-Center Viewing Technique.
c. Countering of the Bleach-Out Effect. Even when soldiers practice off-center viewing, the image of an object bleaches out and becomes a solid tone when viewed longer than two to three seconds. By shifting his eyes from one off-center point to another, the soldier can continue to pick up the object in his peripheral field of vision.
d. Shape or Silhouette. Visual sharpness is greatly reduced at night; therefore, objects must be recognized by their shape or outline. Knowing the design of structures common to the area of operations enhances success with this technique.
3. Dark Adaptation. Dark adaptation is the process by which the human body increases the eyes' sensitivity to low levels of light.
a. Soldiers adapt to darkness at varying degrees and rates. During the first 30 minutes in the dark, eye sensitivity increases about 10,000 times, but not much after that.
b. Dark adaptation is affected by exposure to bright light such as matches, flashlights, flares, or vehicle headlights. Full recovery from these exposures can take up to 45 minutes.
c. Using night vision goggles impedes adaptation. However, if a soldier adapts to the dark before donning the goggles, he gains full dark adaptation within two minutes when they are removed.
d. Soldiers must know that color perception decreases at night. They may be able to distinguish light and dark colors depending on the intensity of reflected light.
e. Visual acuity is also reduced. Since visual sharpness at night is one-seventh of what it is during the day, soldiers can see only large, bulky objects. This means that object identification at night is based on generalized contours and outlines. Depth perception is also affected.
Although night vision devices can help the soldier see at night, they degrade the other senses. Ability to hear, smell, and feel decreases because of the concentration required to use nvds effectively. Leaders should prepare for night operations by using all the senses. On certain operations, this may require that some soldiers not use NVDS. |
4. Planning the use of Night Vision/Sensor Assets. Leaders must develop a night vision plan that interlocks sectors of NVD employment much like that planned for interlocking weapon fire sectors. Often, using NVDs requires repositioning to ensure full coverage of an area. Thermal sights should be kept on a wide field of view until engagement or sector coverage will have gaps. To best use weapons with image intensification nightsights, some NVDs should be used forward of the firing positions to aid in target identification. Night OPs using NVDs can provide target identification for direct-fire weapons and then, with the use of tracers, quickly direct fire onto targets. Use of a three-soldier element at squad level during movement can enhance enemy detection and destruction.
a. One soldier uses unsupported night-adapted vision.
b. One soldier uses the AN/PVS-7.
c. One soldier uses the AN/PVS-4 mounted on the M16 rifle.
5. Night Operation Tips and Techniques. To the infantryman, the dark of night is a helper. It offers advantages to the soldier familiar with operating during darkness, but to those not familiar with darkness, the known appears to become the unknown.
a. Land Navigation.
(1) Routes may be marked with chemical lights, flashlights, or cans filled with diesel-soaked dirt and set alight. Special precautions must be taken to ensure that markers are shielded from enemy observation.
(2) Luminous panels can be used to identify vehicles, road guards, and turning points. Panels are arranged in various patterns for different unit identification.
b. Equipment.
(1) The first rule of night operations: do not ignore the night capability of devices not usually considered night operations equipment; for example:
(a) Binoculars, direct-fire scope, or any image magnifying optical equipment will also enhance night vision because they focus more light in the eye than the unaided eye can gather.
(b) The lensatic compass has luminous markings and detents that allow it to be set for night navigation without using a light.
(2) Ground surveillance radars are effective when oriented along the direction of attack to report and correct deviations for the attacking force. GSRs are also effective when employed in combination with thermal sight equipment to overwatch movement of attacking forces.
(3) At ranges of less than 800 meters, operators tend to underestimate range by as much as 25 percent. Range estimation errors can be reduced by teaching operators to relate targets to terrain features at ranges determined by daylight reconnaissance and map study.
(4) Rough triangulation from two or more night observation posts is useful in reducing range estimation errors.
(5) For moving targets, a ground surveillance radar can provide effective target location information.
(6) Seismic, magnetic, and electromagnetic sensors can detect the presence of personnel or vehicles; however, these systems cannot discriminate between types of vehicles or between civilians and enemy. For this reason, night observation devices must be used in combination with sensors.
(7) Long-range systems and devices are employed at the maximum range that terrain and operator expertise will allow to permit early identification of advancing targets.
(8) Proper use of infrared aiming devices, such as the AN/PQ-4(A), can greatly enhance a platoon's night fighting capability. Care must be taken to ensure that the devices are properly mounted and zeroed to the weapon. Indiscriminate or unsupervised use can result in compromising the platoon's position, whether in offense or defense. Proper use of scatter shields can significantly reduce this risk of early detection. These devices are very effective in a MOUT environment.
c. Illumination.
(1) Flares should be dropped at irregular intervals beyond and on line with the objective to provide orientation. This technique compromises surprise, however, and should be used only in emergency situations or when a subunit becomes so disoriented it hampers mission success.
(2) Areas other than the attack areas may be illuminated to mislead the enemy.
d. Smoke Obscurants.
(1) White phosphorus smoke can be fired on the objective as a heading reference.
(2) Smoke is as effective at night as in the day in reducing visibility. Except for thermal imagery devices, electro-optical night observation devices cannot penetrate heavy smoke.
e. Security.
(1) Noise signatures are reduced as much as possible.
(2) Rock-filled cans suspended on barrier wire or across approach routes into defensive positions can provide intrusion warning.
(3) Blue light is much more difficult to see at night than red light. However, it does hamper night vision more than red light.
(4) Command posts and trains have problems with security at night because of their high noise signature from generators. The noise may be masked by placing generators in pits and surrounding them with bales of hay or vehicles. Placing generators in wooded or built-up areas not only helps dampen the noise, but scatters it as well, making it harder to pinpoint the noise source.
f. Engineer. Engineer missions do not change during darkness, but employment may. For a night attack, the engineers move forward with infantry to begin breaching operations under cover of darkness; they must mark their breaches, however, so the main body can find them with a minimum of trouble. Chemical lights or fluorescent tape on stakes is a good technique. The first unit to move through the breach sends back guides to meet other units and guide them through the enemy obstacle system.
g. Maneuver.
(1) All night maneuvers are kept simple. Complex operations at night may not work.
(2) Animals of all types--cows, monkeys, wild boars, horses, dogs, buffalos have been used successfully by other armies throughout history to probe enemy defenses and cause the defender to reveal gun positions, minefields, barriers, and wire.
(3) Commanders should consider occupying alternate or supplementary positions after dark so that the attacker's artillery fires and assault will be directed against an unoccupied area.
(4) Consideration should be given to relocating reserves after dark, since the enemy may prefer to use artillery rather than maneuver to breakup counterattacks.
(5) Reserve units whose position has been detected in the daytime should be moved, if at all possible.
h. Personnel.
(1) Apprehension rises significantly during darkness and it becomes more difficult to get soldiers to eat, especially if combat is anticipated. They must then contend with the natural "low" that occurs between 0300 and 0600 hours.
(2) Sleep deprivation has numerous effects on the body, and commanders should be aware of this during planning.
(3) When planning night operations, consideration must be given to the method that will be used to mark locations where casualties are to be collected so they can be found by medical personnel and evacuated. Collecting casualties at the assault position or objective rally point is a technique that can speed evacuation.
(4) The commander of a unit that is to conduct a night attack must give thought to his litter teams, especially how he will man them.
(5) Aidmen must reconnoiter the routes from casualty collection points to the battalion aid station during daylight and again during darkness. This is especially critical during a night defense.
i. Combat Service Support.
(1) Leaders should plan for a significant increase in consumption of batteries, flashlights, and illumination rounds (including tracers) when planning for night operations.
(2) If aerial resupply is to be used, a method to guide the aircraft into position is required. A directional light source, such as a strobe light or a chemical light on a helmet, may be used.
(3) Ammunition prestock efforts require careful planning if they are to be effective. Prestock locations must be clearly identified and marked so they can be found during darkness, even by a unit other than the one that installed the prestock.
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