Navigation

When map and compass skills are combined with fitness and foot travel, the result is navigation. Search and Rescue operations will not succeed if operators are unable to successfully navigate between two points. The following lesson will cover basic navigation skills.

*The following information relies heavily on personal experience and the National Association for Search and Rescue's (NASAR) Fundamentals of Search and Rescue 2nd Edition handbook.*

Image by Henk-Jan Geel

Using a Map with a Compass

When used in conjunction, the map and compass are powerful tools. It helps to orient the map when you are reading it. An important step you can take in the field to try to correlate what you see on the ground with what you are looking at on a map is to orient the map. This helps avoid confusion and will assist you in making sense of where you are trying to go. Orienting a map simply means you are lining up the magnetic north direction on the map, with the magnetic north of the compass. You can do this by lining up the orienteering lines on a compass with meridian lines on the map while ensuring the north arrow on the map is parallel with the compass needle. Watch the video below for a demonstration on how to orient a map:

 

 

Finding and transferring bearings, either from the field to the map or from the map to the field, will allow you to navigate more accurately. It will also make it easier for you to change directions, or communicate your location during SAR operations. If you are unsure of where you are located on the map, you can use a triangulation technique known as resection to discover your approximate location. By taking an azimuth reading to two (or more) known points from your location, you can subtract 180 degrees to calculate the back azimuth from those points and draw them on the map. Where the lines intersect from those known points is where you are on the map.

 

Alternatively, if you know where you are on the map, you can use a triangulation process known as an intersection to discover a known point. First, you must take an azimuth from a known point to an unknown point and transfer the bearing onto your map. You then must move to a second known point and take the azimuth to the same unknown point, again transferring the bearing by drawing a line on the map. Where these two lines intersect is where the unknown point is located on the map.

Using these two techniques may be important if it becomes necessary to coordinate the movement of assets during SAR operations. These concepts are tricky to explain, and watching the following videos will help clarify the process, but ultimately, getting out and practicing the techniques with someone knowledgeable about land navigation is the best way to develop these skills:

 

 

 

 

 

 

 

 

 

 

Navigating Obstacles

Nature rarely presents straight, clear paths to follow, and navigating around dangerous or impassible terrain requires creative and critical thinking. There is no singular right way to move around an obstacle, as long as the method used maximizes safety. A common method used is sometimes called the "box method." The box method is used when you come to an area that is thick with a brush or a body of water, and instead of crossing straight through it, you move at 90-degree angles around the object. This method sounds like a great idea to stay on your original heading, but you will rarely encounter scenarios in nature that will allow you to make a perfect box formation around an obstacle. Often, the best solution will be to study the map, study your surroundings, and plan a route of least resistance rather than a route that offers the shortest distance. Watch the video below to see navigating around difficult terrain in action:

 

 

 

 

 

 

 

Magnetic Declination

This has been covered in several videos up to this point, but it bears repeating. Magnetic north is different from the north that is depicted on a map, and if you are not compensating for this difference, you will not be traveling accurately. A good idea is to acquire a compass that allows you to make the adjustment mechanically, so you do not have to calculate the difference. You could also go through the trouble of drawing the difference on your map ahead of time, but in SAR operations, doing so could cost valuable time. Calculating the difference mathematically means you must know if the declination is east or west and either adding or subtracting depending on if you are making the conversion from the map to compass, or compass to map. If it is an east declination:

  • Map to compass: subtract the declination

  • Compass to map: add the declination

If it is a west declination:

  • Map to compass: add the declination

  • Compass to map: subtract declination

This video will help you see how these adjustments are made in real-time:

This may sound confusing, and it can be. You especially do not want to be thinking about which way to calculate the declination when time is a factor of whether or not a lost or missing person survives. Take the time to be familiar with your equipment, your operating location, and ensure when you arrive at an operation, you can take action with confidence.

Measuring Distance

Modern devices make it relatively easy to keep track of the distance that has been traveled. Unfortunately, modern devices are only as reliable as their power source. Not all batteries are created equal, and most experience a steep decline in longevity when the temperature gets too cold or too hot. Knowing how much ground can be covered by walking a given distance on a flat surface, usually referred to as pace count, can help estimate distance. The process of acquiring your pace count can be done by taking the following steps:

  • Measure a set distance. It doesn't matter if it's 20 yards, 50 meters, or 66 feet, as long as the distance you set is consistent and on as flat a surface as possible.

  • Walk naturally from one end of your set distance to the other, counting every other step. In other words, two steps are your pace.

  • When you get to the end of your set distance, keep a record of how many paces it took you to walk the entire length.

  • Turn around and repeat the process until your pace count is consistently the same.

  • Calculate your distance by keeping track of how many times you reached your pace count. For example, if your pace count is 50 paces to go100 meters, every time you count to 50, make a mark on your map (or by using some other system of keeping track). To check how far you traveled, count the number of marks. If there are five marks on the map, you have traveled approximately 500 meters.

As you can imagine, there are a lot of factors that affect pace count, such as the type and weight of the ready pack you wear, what type of footwear you have on, what season you are dressed for, what time of day it is, what type of terrain you are walking over, how fast you are moving, etc. No matter how perfectly you practice your pace count, or how many scenarios you practice your pace count in, there will always be some factor that throws it off. So bear that in mind as you are estimating your distance traveled, and realize you may be short or far from your desired destination. Watch the video below to learn more about pace count:

Sometimes it may be necessary to measure the distance of a road or trail on the map to calculate how far you will need to travel. Estimating travel distance will also allow you to estimate how much time it may take you to get from one point to another. An easy way to calculate distances like this is to use the straight edge of a piece of paper and slowly line it up along the road on the map. As you move the edge of the paper along the road on the map, make light pencil marks at regular intervals from the start point to the endpoint. You can then use the distance scale on the map to determine how far the distance will be. Watch the video below to see how this technique is performed:

Global Positioning System

The Global Positioning System (GPS), is a series of satellites in orbit around the Earth that is constantly sending a signal down to the Earth's surface. A GPS device then receives these signals, interprets the data, and can give you more precise data about your location. GPS devices need to detect at least four signals to accurately describe your location, and the satellites are orbiting in a way so that there should be at least six over the horizon at any given time. Some GPS systems use other land-based infrastructure features to be more precise, but GPS used during SAR operations will most likely only rely on the satellite network. Although GPS is very accurate and reliable in many cases, there are some challenges that anyone using these devices should be aware of:

  • The device requires line-of-sight to the satellites and does not work in all-terrain (e.g., deep canyons, heavy tree canopy, inclement weather, urban environments with tall buildings, etc.).

  • GPS should not be used as the sole navigation device; it should complement other conventional approaches to navigation.

  • The less-than-perfect accuracy is not always acceptable, especially for altitude.

  • Human error (input error) is always a possibility.

  • The position display can easily be misread, and the display can give the impression of far greater accuracy than the device is capable of producing.

  • Today's GPS technology requires greater energy consumption, and batteries can fail at any time. Pay attention to the time ratings on the batteries of any GPS devices you are using.

  • Many GPS units are not waterproof and require special protection during bad weather, or when operating near water sources.

  • Because of orbit paths, there may be times of the day when satellites do not offer the best line of sight to the GPS receiver. There are several websites that can help you determine the optimal time to use GPS devices in your specific region such as In-The-Sky.org.

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