Navigation
Note: The following information is based on recommendations from the National Association for Search and Rescue's (NASAR) Fundamentals of Search and Rescue 2nd Edition handbook.
Learning Objectives
Upon completing this module, responders should be able to:
Field Navigation Techniques: Demonstrate taking a field bearing, working around obstacles (aiming off), and executing a dead reckoning navigation plan.
Position Fixes & Triangulation: Perform intersection and resection (triangulation) using a map and compass to locate unknown points or fix a responder's position.
Pace Counting & Distance Estimation: Establish an accurate personal pace count to measure ground distance across varied terrain.
GPS Operation & Satellite Factors: Utilize handheld GPS units alongside traditional map/compass skills while managing power reserves in cold environments.
1. Field Navigation & Bearing Operations
Executing a search line or traveling to an assigned grid requires integrating map measurements with physical ground movement.
Core Field Techniques
Taking a Bearing from a Map: Lay the compass edge along your current location and target destination. Rotate the bezel until the orienting lines align with the map’s grid/true north lines. Read your target azimuth at the index mark.
Following an Azimuth ("Red in the Shed"): Hold the compass flat and level in front of your chest. Turn your entire body until the magnetized red needle sits directly inside the orienting arrow ("put the red in the shed"). Your direction-of-travel arrow now points toward your destination.
Aiming Off: Intentionally setting a bearing slightly to the left or right of a specific target (such as a trail junction or stream confluence). When you reach the linear feature (e.g., a river), you know with certainty which way to turn to reach your target.
Bypassing Obstacles: When encountering an impassable hazard (e.g., a swamp, cliff, or thicket):
Turn 90° away from your original path and count your paces until clear of the obstacle.
Turn back 90° to your original azimuth and walk past the obstacle.
Turn 90° back toward your original line and walk the exact same pace count recorded in step 1.
Turn 90° back onto your original azimuth to resume your path seamlessly.
2. Fixing Positions & Triangulation
When terrain features obscure landmarks or team coordinates are requested, map-and-compass plotting techniques allow searchers to pinpoint exact locations.
Key Plotting Methods
Resection (Triangulation): A method used to locate your own unknown position on a map:
Identify two or three prominent, visible landforms in the field that can also be located on your map (e.g., a distinct mountain peak, water tower, or bridge).
Take a magnetic compass bearing to each landmark and convert them to grid bearings.
Calculate the back azimuth (opposite direction) for each bearing:
If the bearing is less than 180°, add 180°.
If the bearing is greater than 180°, subtract 180°.
Draw lines along those back-azimuth angles on the map from each landmark. Your location is at the intersection point of the lines.
Intersection: A method used to locate an unknown distant object or target:
Take a bearing to the target from your current known position and plot a line on the map.
Move a known distance to a second location and take a second bearing to the same target.
Draw the second line on the map. The target is located where the two lines cross.
3. Pace Counting & Distance Estimation
Estimating distance traveled on foot is critical when navigating in low visibility, dense timber, or night operations.
Establishing Your Pace Count
Pace Definition: One pace equals two steps (every time your dominant foot hits the ground).
The 100-Meter Standard: Measure a 100-meter flat course. Walk the course at a natural stride and count your double-steps (e.g., 62 paces per 100 meters).
Terrain Adjustments: Pace counts increase (shorter strides) when moving uphill, through thick brush, or in deep snow. Pace counts decrease on steep downhill stretches.
Tracking Paces: Use pace beads (tally beads) attached to your pack strap or move a small rock from one pocket to another for every 100 meters traveled to avoid losing count over long distances.
4. GPS Operation & Electronic Navigation
Global Positioning System (GPS) receivers provide precise location data, but they must complement—never replace—traditional map and compass mastery.
Operational Principles
Datum Alignment: Always verify that your GPS Map Datum matches the datum printed on your paper topographic map (most commonly NAD83 or WGS84). Mismatched datums create significant position errors.
Coordinate Displays: Ensure your GPS unit is set to display coordinates in the operational format requested by Incident Command (e.g., USNG, UTM, or Lat/Long).
Power Management: Cold weather rapidly degrades lithium and alkaline battery performance. Store backup batteries and handheld GPS units inside an inner jacket pocket close to body heat when not actively taking a reading.
Satellite Line-of-Sight: Deep canyons, dense tree canopies, and heavy rock walls can degrade satellite signal strength or cause multipath errors. Always cross-check GPS readouts against visual terrain features and your compass.
5. Magnetic Declination & Bearing Conversions
Maps are oriented to True North (or Grid North), but a compass needle always points to Magnetic North. The angular difference between True North and Magnetic North at any given location is called Magnetic Declination. Failing to adjust for declination will cause field responders to drift significantly off course over long distances.
Types of Declination
East Declination: Occurs when Magnetic North lies to the east (right) of True North.
West Declination: Occurs when Magnetic North lies to the west (left) of True North.
Field Rule of Thumb: Declination values change over time and vary by location. Always check the declination diagram in the margin of your topographic map for the target search area.
Converting Bearings
If your compass does not have a tool-adjustable declination scale built into the bezel, you must perform manual mathematical adjustments when transferring bearings between a map and the field:
Map to Field (True to Magnetic):
West Declination:Add declination degrees to your map bearing (Mag = True + West).
East Declination:Subtract declination degrees from your map bearing (Mag = True - East).
Field to Map (Magnetic to True):
West Declination:Subtract declination degrees from your field bearing (True = Mag - West).
East Declination:Add declination degrees to your field bearing (True = Mag + East).
(Memory Aid: "Mag to Grid, Add West" / "Grid to Mag, Subtract West")