Infantry Drills

FM 3-21.8 – Chapter 3 – Section IV – Route Selection and Navigation

Section IV – Route Selection and Navigation

3-89.     During planning and preparation for tactical movement, platoon leaders analyze the terrain from two perspectives. First, they analyze the terrain to see how it can provide tactical advantage, both to friendly and enemy forces. Second, they look at the terrain to determine how it can aid navigation. Leaders identify any areas or terrain features that dominate their avenue of approach. These areas are almost always  considered key terrain and provide the unit possible intermediate and final objectives.

3-90.     Ideally, the leader identifies along his route not only ground that is good for navigation, but also ground that facilitates destroying the enemy should contact occur. If the leader wants to avoid contact, he chooses terrain that will hide the unit. If he wants to make contact, he chooses terrain from where he can more easily scan and observe the enemy. On other occasions, the leader may require terrain that allows stealth or speed. Regardless of the requirement, the leader must ensure that most of the terrain along his route provides some tactical advantage.

3-91.     Route Selection and Navigation are made easier with the aid of technology. Global Positioning System (GPS) devices or Force XXI Battle Command Brigade and Below Systems (FBCB2) enhance the Infantry platoon’s ability to ensure they are in the right place at the right time and to determine the location of adjacent units.

Navigation Aids

3-92.     There are two categories of navigational aids: linear; and point. Linear navigational aids are terrain features such as trails, streams, ridgelines, woodlines, power lines, streets, and contour lines. Point terrain features include hilltops, and prominent buildings. Navigation aids are usually assigned control measures to facilitate communication during the movement. Typically, linear features are labeled as phase lines while point features are labeled as checkpoints (or rally points). There are three primary categories of navigation aids: catching features; handrails; and navigational attack points.

Catching Features

3-93.     Catching features are obvious terrain features that go beyond a waypoint or control measure and can be either linear or point. The general idea is that if the unit moves past its objective, limit of advance, or checkpoint, the catching feature will alert them that they have traveled too far.

The Offset-Compass Method

3-94.     If there is the possibility of missing a particular point along the route (such as the endpoint or a navigational attack point), it is sometimes preferable to deliberately aim the leg to the left or right of the end point toward a prominent catching feature. Once reached, the unit simply turns the appropriate direction and moves to the desired endpoint. This method is especially helpful when the catching feature is linear.

Boxing-In the Route

3-95.     One of the techniques leaders can use to prevent themselves from making navigational errors is to “box in” the leg or the entire route. This method uses catching features, handrails, and navigational attack points to form boundaries. Creating a box around the leg or route assists in more easily recognizing and correcting deviation from the planned leg or route.

Handrails

3-96.     Handrails are linear features parallel to the proposed route. The general idea is to use the handrail to keep the unit oriented in the right direction. Guiding off of a handrail can increase the unit’s speed while also acting as a catching feature.

Navigational Attack Points

3-97.     Navigational attack points are an obvious landmark near the objective, limit of advance, or checkpoint that can be easily found. Upon arriving at the navigational attack point, the unit transitions from rough navigation (terrain association or general azimuth navigation) to point navigation (dead reckoning). Navigational attack points are typically labeled as checkpoints.

Route Planning

3-98.     Route planning must take into account enabling tasks specific to tactical movement. These tasks facilitate the overall operation. Tactical movement normally contains some or all of the following enabling tasks:

– Planning movement with GPS waypoints.

– Movement to and passage of friendly lines.

– Movement to an objective rally point (ORP).

– Movement to a phase line of deployment.

– Movement to a limit of advance.

– Linkup with another unit.

– Movement to a patrol base or assembly area.

– Movement back to and reentry of friendly lines.

3-99.     Leaders first identify where they want to end up (the objective or limit of advance). Then, working back to their current location, they identify all of the critical information and actions required as they relate to the route. For example, navigational aids, tactical positions, known and templated enemy positions, and friendly control measures. Using this information, they break up their route in manageable parts called legs. Finally, they capture their information and draw a sketch on a route chart. There are three decisions that leaders make during route planning:

(1)     The type of (or combination of) navigation to use.

(2)     The type of route during each leg.

(3)     The start point and end point of each leg.

3-100.  The leader assesses the terrain in his proposed area of operation. In addition to the standard Army map, the leader may have aerial photographs and terrain analysis overlays from the parent unit, or he may talk with someone familiar with the area.

3-101.  To control movement, leaders use axes of advance, directions of attack, infiltration lanes, phase lines, probable lines of deployment, checkpoints (waypoints), final coordination lines, rally points, assembly areas, and routes.

Types of Navigation

3-102.  There are three types of navigation: terrain association; general azimuth method; and point navigation. Leaders use whichever type or combination best suits the situation.

Terrain Association

3-103.  Terrain association is the ability to identify terrain features on the ground by the contour intervals depicted on the map. The leader analyzes the terrain using the factors of OAKOC and identifies major terrain features, contour changes, and man-made structures along his axis of advance. As the unit moves, he uses these features to orient the unit and to associate ground positions with map locations. The major advantage of terrain association is that it forces the leader to continually assess the terrain. This leads to identifying tactically-advantageous terrain and using terrain to the unit’s advantage.

General Azimuth Method

3-104.  For this method, the leader selects linear terrain features; then while maintaining map orientation and a general azimuth, he guides on the terrain feature. Advantages of the general azimuth method are that it speeds movement, avoids fatigue, and often simplifies navigation because the unit follows the terrain feature. The disadvantage is that it usually puts the unit on a natural line of drift. This method should end like terrain association, with the unit reaching a catching feature or a navigational attack point, then switching to point navigation.

Point Navigation

3-105.  Point navigation, also called dead reckoning, is done by starting from a known point and then strictly following a predetermined azimuth and distance. This form of navigation requires a high level of leader control because even a slight deviation over the course of a movement can cause navigation errors. This method uses the dismounted compass and a distance from the pace man (or a vehicle’s odometer when mounted) to follow a prescribed route. Point navigation requires the leader to follow these steps:

– Use the compass to maintain direction.

– Use the pace man’s pace or a vehicle odometer to measure the distance traveled for each leg or part.

– Review the written description of the route plan to help prevent navigational errors.

3-106.  When performed correctly, point navigation is very reliable, but time consuming. It is best used when the need for navigational accuracy outweighs the importance of using terrain. Point navigation is particularly useful when recognizable terrain features do not exist or are too far away to be helpful. For example, deserts, swamps, and thick forest make terrain association difficult. Using point navigation early on in a long movement can stress the compass man and it may be advisable to switch him. One of the problems with point navigation is negotiating severely restrictive terrain or danger areas.

Combinations

3-107.  Leaders can benefit from combining the three types of navigation. Terrain association and the general azimuth method enable leaders to set a rough compass bearing and move as quickly as the situation allows toward a catching feature or a navigational attack point. Once reached, leaders switch to point navigation by paying extremely close attention to detail, taking as much time as necessary to analyze the situation and find their point. Terrain association and the general azimuth method allow for some flexibility in the movement, and therefore do not require the same level of control as point navigation. Point navigation, on the other hand, enables leaders to precisely locate their objective or point.

Route Types

3-108.  There are three types of routes leaders can choose from: those that follow linear terrain features; those that follow a designated contour interval; and those that go cross compartment. Terrain association can be used with all three route types. The general azimuth method is used with the contour and terrain feature method. Point navigation is used primarily with cross compartment.

Terrain Feature

3-109.  Following a terrain feature is nothing more than moving along linear features such as ridges, valleys, and streets. The advantage of this method is that the unit is moving with the terrain. This is normally the least physically taxing of the methods. The disadvantage is that following terrain features also means following natural lines of drift, which leads to a higher probability of chance contact with the enemy.

Contouring

3-110.  Contouring (remaining at the same height for the entire leg) follows the imaginary contour line around a hill or along a ridgeline. Contouring has two advantages. First, it prevents undue climbing or descending. Second, following the contour acts as handrail or catching feature. The disadvantage of contouring is that it can be physically taxing.

Cross Compartment

3-111.  Cross compartment means following a predetermined azimuth and usually means moving against the terrain. The advantage of this method is that it provides the most direct route from the start point to the end point of the leg or route. There are two primary disadvantages to this type of route. First, this method can be physically taxing. Second, the unit might expose itself to enemy observation.

Develop a Leg

3-112.  The best way to manage a route is to divide it into segments called “legs.” By breaking the overall route into several smaller segments, the leader is able to plan in detail. Legs typically have only one distance and direction. A change in direction usually ends the leg and begins a new one.

3-113.  A leg must have a definite beginning and ending, marked with a control measure such as a checkpoint or phase line. (When using GPS, these are captured as waypoints.) When possible, the start point and end point should correspond to a navigational aid (catching feature or navigational attack point).

3-114.  To develop a leg, leaders first determine the type of navigation and route that best suits the situation. Once these two decisions are made, the leader determines the distance and direction from the start point to the end point. He then identifies critical METT-TC information as it relates to that specific leg. Finally, leaders capture this information and draw a sketch on a route chart (Figure 3-23).

 

Figure 3-23. Sketch of legs example.

Execute the Route

3-115.  Using decisions about the route and navigation made during planning and preparation, leaders execute their route and direct their subordinates. In addition to executing the plan, leaders—

– Determine and maintain accurate location.

– Designate rally points.

Determine Location

3-116.  Leaders must always know their units location during movement. Without accurate location, the unit cannot expect to receive help from supporting arms, integrate reserve forces, or accomplish their mission. To ensure accurate location, leaders use many techniques, including:

– Executing common skills.

– Designating a compass man and pace man.

– Using GPS / FBCB2.

Common Skills

3-117.  All Infantrymen, particularly leaders, must be experts in land navigation. Important navigation tasks common to all include—

– Locating a point using grid coordinates. Using a compass (day/night).

– Determining location using resection, intersection, or modified resection.

– Interpreting terrain features.

– Measuring distance and elevation.

– Employing a GPS / FBCB2.

Compass Man

3-118.  The compass man assists in navigation by ensuring the lead fire team leader remains on course at all times. The compass man should be thoroughly briefed. His instructions must include an initial azimuth with subsequent azimuths provided as necessary. The platoon or squad leader also should designate an alternate compass man. The leader should validate the patrol’s navigation with GPS devices.

Pace Man

3-119.  The pace man maintains an accurate pace at all times. The platoon or squad leader should designate how often the pace man is to report the pace. The pace man should also report the pace at the end of each leg. The platoon or squad leader should designate an alternate pace man.

Global Positioning Systems

3-120.  GPSs receive signals from satellites or land-based transmitters. They calculate and display the position of the user in military grid coordinates as well as in degrees of latitude and longitude. During planning, leaders enter their waypoints into the GPS. Once entered, the GPS can display information such as distance and direction from waypoint to waypoint. During execution, leaders use the GPS to establish their exact location.

 

NOTE: Leaders need to remember that GPS and digital displays are not the only navigational tools they can use. The best use of GPS or digital displays is for confirming the unit’s location during movement. Terrain association and map-reading skills are still necessary skills, especially for point navigation. Over reliance on GPS and digital displays can cause leaders to ignore the effects of terrain, travel faster than conditions allow, miss opportunities, or fail to modify routes when necessary.

Designate Rally Points

3-121.  A rally point is a place designated by the leader where the unit moves to reassemble and reorganize if it becomes dispersed. It can also be a place for a temporarily halt to reorganize and prepare for actions at the objective, to depart from friendly lines, or to reenter friendly lines (FM 1-02). Planned and unplanned rally points are common control measures used during tactical movement. Planned rally points include objective rally point(s) (ORP), initial rally point(s) (IRP), and reentry rally point(s) (RRP). Unplanned rally points are enroute rally points, near side rally points, and far side rally points. Despite the different types of rally points, the actions that occur there are generally the same.

3-122.  Prior to departing, leaders designate tentative rally points and determine what actions will occur there. When occupying a rally point, leaders use a perimeter defense to ensure all-around security. Those rally points used to reassemble the unit after an event are likely to be chaotic scenes and will require immediate actions by whatever Soldiers happen to arrive. These actions and other considerations are listed in Table 3-6.

Table 3-6. Actions at rally point.

Rally Points

Soldier Actions at an RP

Other Considerations

Select a rally point that—

·      Is easily recognized.

·      Is large enough for the unit to assemble.

·      Offers cover and concealment.

·      Is defensible for a short time.

·      Is away from normal movement routes and natural lines of drift.

Designate a rally point by one of the following three ways:

·      Physically occupy it for a short period.

·      Use hand-and-arm signals (either pass by at a distance or walk through).

·      Radio communication.

·      Establish security.

·      Reestablish the chain of command.

·      Account for personnel and equipment status.

·      Determine how long to wait until continuing the unit’s mission or linkup at a follow-on RP.

·      Complete last instructions.

 

·     Travel time and distance.

·     Maneuver room needed.

·     Adjacent unit coordination requirements.

·     Line of sight and range requirements for communication equipment.

·     Trafficability and load bearing capacity of the soil (especially when mounted).

·     Ability to surprise the enemy.

·     Ability to prevent being surprised by the enemy.

·     Energy expenditure of Soldiers and condition they will be in at the end of the movement.

 


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