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Appendix A

RECONNAISSANCE: CATEGORIES, CAPABILITIES, AND LIMITATIONS

1. Background

a. This appendix provides an expanded discussion of the categories of reconnaissance, with specific emphasis on the capabilities and limitations of each category. Also included are samples of selected imagery reconnaissance products (photo and infrared) which are intended to familiarize the reader with the basic characteristics of the images.

b. Readers should note that the capabilities and limitations of the categories of reconnaissance described in this appendix are generic and are not associated with specific reconnaissance systems, vehicles, or sensors.

c. There are four general categories of reconnaissance: visual, imagery, electronic, and weather. Imagery reconnaissance is further subdivided into optical and non-optical imagery.

2. Visual Reconnaissance

a. Sources. Visual reconnaissance can come from a wide range of sources and simply entails an observer reporting on what is seen. At surface level, the source could be an individual, a reconnaissance unit, SOF team, naval surface or subsurface vessel. Aerial sources may be a variety of aircraft types and missions. A passing strike aircraft, airborne FAC, escort aircraft, or dedicated reconnaissance aircraft could provide visual recce information.

b. SOF

(1) SOF forces are a valuable reconnaissance asset. A special reconnaissance (SR) mission can benefit a wide range of users. SOF conduct SR missions when there is a need to obtain or verify information about enemy capabilities, intentions, and activities or to gather data about meteorological, hydrographic, or geographic characteristics of an area. SR missions complement national and theater assets through border reconnaissance and deep penetration missions to obtain specific, time-sensitive information of strategic and tactical significance. SR may complement other collection methods where there are constraints of weather, terrain-masking, hostile countermeasures, and/or other systems availability.

(2) SR is a HUMINT function that places US or US-controlled "eyes on target" in hostile, denied, or politically sensitive territory when authorized. SOF may conduct these missions unilaterally or in support of conventional non-SOF operations. SOF may use advanced reconnaissance and surveillance techniques and equipment. Sophisticated clandestine collection methods and indigenous assets may also be employed.

c. Advantages

(1) In addition to providing information about the enemy, visual reconnaissance can be useful for obtaining timely information on the terrain and weather. For example, an aircrew coming off target could pass timely tips on target area weather to an inbound flight, giving them time to adjust their tactics.

(2) Visual reconnaissance is well suited to answering "yes or no" or "true/false" questions about the general condition or presence of a force or structure. Reconnaissance teams can provide data on enemy activity in named areas of interest (NAI). Examples follow: "Are enemy armored forces moving in the vicinity of NAI 4?" or "Is the bridge at Remagen still standing?" Simple visual reports such as "the bridge span is in the river," or "there are many tanks in the downtown area moving south" are examples where visual reconnaissance can be quite effective in observing and reporting basic facts about easily-observed activity.

(3) Direct observation and reporting are very reliable and fast, especially when done by trained aircrews or reconnaissance teams. Air and reconnaissance teams can identify many types of military equipment. They are equipped with a variety of communications systems enabling them to report enemy activity quickly, and in some cases, directly to the requester.

d. Disadvantages

(1) Aircrews can provide very timely battle information, because they can transmit a report while literally still over the target. However, this advantage is significantly effected by the limitations of human vision. Because the aircrew must fly the aircraft and avoid lethal threats in a high threat environment, they can only concentrate on the reconnaissance "target" or objective for a short time. In addition, weather conditions (low clouds, rain, and fog) and terrain features (hills and trees) can obstruct the aircrew's view of the target. Finally, an enemy can use camouflage, concealment, and deception (CCD) techniques to avoid visual detection.

(2) Because of these limitations, visual reconnaissance by aircrews is not well suited to situations in which precise counts and/or precise details are required. Visual reconnaissance may not be able to provide users with precise counts of vehicles and/or soldiers on a battlefield and it is not the best way to make precise assessments such as the dimensions or construction of a structure. Ground-based visual reconnaissance by reconnaissance teams, on the other hand, may be able to provide accurate counts of troops or equipment. When considering a request for visual reconnaissance, its capabilities and limitations must be weighed against the value of the facts or data needed.

3. Imagery Reconnaissance

Note: Photos A-1, A-2, A-3, and A-4 are of the same bridge along a low level training route in the Appalachian Mountains. They were provided courtesy of Fighter Squadron 101, Naval Air Station Oceana, Virginia.

a. Optical

(1) In essence, optical sensors are similar to the commercial still or video cameras used to take personal pictures. In order to produce a photographic image, optical sensors require their targets to be illuminated to some extent by visible light. Further, optical sensors require a clear, unobstructed "look" at their target without interference from clouds or physical obstructions.

(2) Perhaps the most striking similarity between a commercial 35mm framing camera and an optical sensor is that both trade resolution (i.e., the ability to record fine detail) for lateral coverage, and vice versa. A telephoto lens on our personal cameras (or on an optical sensor) we can record more detail about an object by "zooming in" on it but does so at the expense of lateral coverage. By the same token, the same camera or optical sensor can widen its area of coverage by moving farther away from the target but loses detail (i.e., resolution) in the process.

(3) There are various optical imagery sensors available for military reconnaissance purposes. Each has its own distinct capabilities and each provides a different type of information to the reconnaissance interpreter and user.

(a) Vertical Imagery.
• Vertical Imagery provides a two-dimensional overhead view of the target (Figure A-1). This type of imagery allows the interpreter to see a map-like picture in which all objects are of the same scale. It allows the user to determine precise horizontal relationships (i.e., bunker "X" is exactly 100 meters from road intersection "Y" on a bearing of 127 degrees) and provides a view of objects on the ground unobstructed by vertical development (such as terrain, buildings, etc.). Vertical imagery is ideally suited to determining precise locations of objects on the surface and to counting and identifying these objects.

• Photo A-1 is an overhead image of a bridge. This is also an extreme example of "pinpoint" imagery. It "zooms in" on the detail of the bridge and very little of the surrounding area is visible in the image. In this view, two of the piers are visible, but it is unclear whether they are concrete, wood, or steel. The vertical perspective offers a good sense of scale. The shadow cast on the water gives an indication of the height of the bridge, and if the time the picture was taken is known an accurate estimate of the height can be made.

(b) Oblique Imagery.
• Oblique Imagery employs sensors which provide an angled, three-dimensional view of the reconnaissance target (Figure A-2). This perspective gives the interpreter/user a view of the sides of the objects "on film," permitting the interpreter/user to determine approximate heights of these objects and to make judgments concerning their identity and the materials used in their construction.

• Oblique imagery is ideally suited to the task of providing information about vertical structures for targeting and battle damage assessment purposes. An oblique image of a bridge, for example, will show the interpreter what support structures exist under the bridge, how many spans make up the bridge, and (perhaps) the kinds of materials used in the bridge's construction. Using this kind of information, the most appropriate weapon and delivery means to attack and destroy the bridge can be selected. An oblique image can also aid strike aircrews during mission planning, by showing what the bridge will look like during their attack run-in (see Photo A-2).

• Oblique imagery often eliminates the necessity for reconnaissance vehicles to fly directly over the target -the platform can instead stand off at a distance from the target. This offers the significant advantage of recording the desired images while keeping the reconnaissance vehicle outside sensitive borders/boundaries or out of range of hostile threats. The oblique perspective on the bridge offers a better look at the piers allowing determination that they are of concrete construction. Photo A-2 also reveals one pier is at the edge of the river, and the other is on a ridge of rocks.

• Photo A-3 depicts the same bridge as in photo A-1 but is taken from a different angle and at a greater standoff range. While, this image shows much more of the surrounding scene, the lower angle gives an idea of the height and thickness of the bridge piers.

(c) Panoramic Imagery. Panoramic imagery combines features of both vertical and oblique imagery. Panoramic sensors "scan" from side to side (often from horizon to horizon) providing a vertical pinpoint perspective of objects directly below the reconnaissance air vehicle along with an oblique perspective of objects to the sides of the vehicle (Figure A-3). As in the case of oblique imagery, objects on panoramic imagery will not be to scale--objects farther away will be smaller and distorted on the image, and closer objects will appear larger.

b. Non-Optical. The two basic, and widely-employed, types of non-optical imagery are infrared and radar. Unlike the optical sensors discussed previously, these non-optical sensors function regardless of the presence or absence of visible light and can be used at night as well as during the day. Imagery reconnaissance (other than visible spectrum) is summarized in a sensor/intelligence matrix included as table A-1.

(1) Infrared. Infrared (IR) sensors detect infrared (thermal or heat) radiation. This radiation is adjacent to visible light in the electromagnetic spectrum and has similar characteristics. IR sensors produce their images by detecting very small differences in the heat energy being radiated by various objects, parts of objects, and materials. IR sensor systems have become quite sophisticated and are now capable of producing imagery resolution virtually on a par with that of optical imagery. Like optics, IR shows objects in detail, but the energy is attenuated by atmospheric particles and moisture (clouds).

(a) In addition to their night reconnaissance capabilities, IR sensors (whether employed in daylight or darkness) can provide types of information which would be unavailable with optical sensors. Because they detect heat emissions, IR sensors can detect the difference between operating and nonoperating vehicles; between fueled and unfueled aircraft; between heated and unheated facilities; and often, between real and decoy objects.

(b) Photo A-4 is an oblique view of the same bridge as in photo A-2 and Photo A-3. It was taken from about the same angle as Photo A-2. On the IR print, the warmer the object, the darker it appears; the cooler the object, the lighter. The ice-covered river appears white because it is cold, while the sun-warmed bridge appears dark. This is the opposite of what appears on the original film negative, where white equates to hot and black equates to cold. IR video is normally the same as film negatives; however, some IR video can be electronically manipulated to appear like the print. "Gray scale" on most IR images (whether on video or film) are normally relative to the spectrum of temperatures in the scene being observed.

(2) Radar. Radar, the second type of non-optical imagery, uses recorded radar returns to produce images. Radar is independent of light conditions and is practically independent of weather conditions, making it a true all-weather sensor. Although some modern radar sensors are capable of producing imagery in which a trained interpreter can distinguish between wheeled and tracked vehicles, the significant advantage of radar imagery is that it is the only near all-weather sensor. However, even the most advanced radar imagery is incapable of producing the resolution quality associated with optical and IR imagery. Long-range sensing capability is available from a number of other sensors, but they all have limits imposed by weather which radar does not. Because radar is line-of-sight, placement of the antenna, such as on a highflying aircraft or on a mountain top, radar can produce imagery of targets at great distances from the sensor, and it can image vast stretches of territory from a single site or during a single mission.

4. Electronic Reconnaissance

a. Electronic reconnaissance supports both SIGINT and electronic warfare (EW) missions. Electronic reconnaissance involves intercepting, identifying, and locating enemy communications and radar emissions such as communication nets (both voice and data communications in encrypted and clear-text modes). Non-communication emitters are also targeted, including early warning, ground control intercept, target acquisition/target tracking, air traffic control, meteorological radars (associated with weapons systems), and digital data command and control radars.

b. By analyzing the enemy's communications and radar emissions, analysts identify an enemy's order of battle and critical nodes to include enemy command posts, high-threat weapon systems, force concentrations, and logistic bases. Commanders can subsequently target enemy critical nodes for destruction, neutralization, or exploitation by multiple lethal and nonlethal systems.

c. Electronic reconnaissance can be conducted by ground, air, sea, and space-based systems, from a friendly or a hostile environment, under all weather conditions, and during the day or at night. However, it is important to note that in order for electronic reconnaissance to successfully detect a target, the target must be emitting electromagnetic energy. If a communications or noncommunications emitter is inactive, the electronic reconnaissance system will be unable to locate, identify, or exploit the emitter. Additionally, an enemy can use electronic deception techniques not only to avoid detection but also to deceive friendly reconnaissance systems.

5. Weather Reconnaissance

a. Weather reconnaissance obtains weather data over areas where more conventional weather observations are not available. Methods for obtaining weather reconnaissance include visual observation and reporting by aircrews, specialized reconnaissance/scout teams, or data recording and reporting from atmospheric sensor equipment capable of obtaining meteorological data at selected altitudes.

b. If you are considering a request for weather reconnaissance, exhaust all other means for obtaining the weather data prior to making such a request. Weather reconnaissance is usually collected only during the course of normal operations, and data is obtained through such routine methods as aircrew debriefings.