Hikers: Know your grid!!!
(Rev 2: 09–14–2019)
The idea for this article stems from reading, ‘Help — I’m Lost’ in the June 2014 edition of the New York State Conservationist. Author & Forest Ranger Scott VanLaer tells the story of a search and the importance of signing in at a trail register. Readers are encouraged to read the linked article as a background.
The trapped hikers had a GPS but apparently did not advise any coordinates during their 9–1–1 call. This seems other than wise. Coordinates are long and require a lot of air time, correct? There is no time for that! Well, this may be partially true if using any one of the three(3) versions of Latitude and Longitude.
N 44° 8.640' W 73° 57.917' or N 44° 8' 38" W 73° 57' 55" or 44.143999, -73.965282 are the three versions, the first being the ‘standard’ version. Ponder how long it would take to say and copy one of those over a static filled 9–1–1 call.
What if there was an alternative that was shorter & easier? Full coordinate options exist, by US National Grid as: 18T WP 8275 8838 & UTM as: 18N 582757, 4888387
Finally, what if just WP 827 883 was a solution? Just eight characters. Well, that is the strong suggestion here; hikers should know their 100 meter or 1 Km grid square. In many cases, just six digits 827 883 as in this example would be all that is need. Six digits!!
What is all this about? Well, US National Grid is the nation’s grid system and it is a federal standard: FGDC-STD-011–2001. The power of it though is when grid lines are placed on map thereby making those maps tools. US National Grid is also the land search & rescue coordinate system as of 2011. So, hikers, would it not be logical to have your smart phones and GPS receivers configured for the same coordinate system that search & rescue responders are supposed to use?
The meaning of 18T visually. It is the Grid Zone Designator.
The meaning of 18T WP visually. It is the 100 Km ID.
827 883 represents a 100m x 100m square area. That is 330' x 330'. Inside of 100 Km ID WP, it is plotted 82.7 % right and 88.3% up.
The graphic from VanLaer’s ‘Help — I’m Lost’ article shows a typical map paradigm; a non-gridded map. Yet, if you went to any convenience store or office supply store to purchase a map, each & every one would have some form of index grid in the margins, usually A-Z, 1–9, etc, typically known as a “bingo” grid. These grids make finding a location easy. However, those bingo grids are non-interoperable, non-transferable to any other map. USGS topographic maps have had UTM grids in margins since inception. What is needed is interoperable, easy to use grid lines on maps. Now, in 2014, due to multiple advancements we can have a USGS topo map with grids overlayed with GIS data of the trail locations (yellow lines).
Tying this all together, we will assume that the lost hikers were not in grid 83 89, the grid closest to Marcy Dam. Then, from a 1 Km grid standpoint, they were trapped and requesting help from either 82 87, 82 88, or 83 88. Obviously, 1 Km square is a pretty large area when you need help, so more precision should be used. But on the night of that attempted rescue, how many thousands of acres were the rangers potentially looking at?
So, as a base-10 system, the user adds digits to the right side for increase precision. 827 883 then means in words, 70% right and 30% up in 1 Km grid 82 88. Use the link and observe the red cross hair at the location.
The minimum information that could be used locally to identify position is 100 meter square USNG (827 883). Regionally, if the location was near another 100 Km ID, then reference the proper 100 Km ID such as WP 827 883. Finally, worldwide, just add the GZD for 18T WP 827 883.
All potential users of US National Grid coordinates need to know some priority facts as follows;
> USNG is functionally same as US Military and NATO Military Grid Reference System (MGRS) in use since 1949!
> Despite being the land SAR standard coordinate system since 2011, the 9–1–1 operator may not be familiar with it, yet. Articles like this are working to change that. So be familiar with web tools GMap4 or Mission Manager to talk any dispatcher through it. Be responsible for your own rescue at some level; might as well start with a good geo-position report. As long as you clearly communicate “US National Grid” and the coordinates, they will get it figured out.
> When entering 827 883 back into a GPS to route to it, the user will just add zeros to the end of the easting and northing. GPS entry would be 18T WP 82700 88300. The fifth digit is 1 meter precision. Be aware that typical GPS devices are only accurate to 3–5 meters. So, while 8 digits (10 meter precision) is fine, 10 digits for 1 meter precision is not more accurate.
> If someone does not like the 100 meter concept as a first pass, ‘good enough’, Geo-position, then merely add a 5,5 which puts the position in the center of the 100 meter grid square. Thus, 827 883 becomes 8275 8835. In many cases the GPS will display its accuracy. As long as accuracy shows less than 10 meters, then an 8 digit coordinate is valid. With tree cover, valleys, etc, it could be possible to see GPS accuracy of 75 meters, as example. In that case the six digit coordinate would be valid but an eight digit coordinate would not be. Certainly the specific 10 meter grid (eight digit coordinate) shall be used and transmitted when known. For this example the 10 meter grid square is already determined as 8275 8838.
> In your app store for your smart phone numerous apps exist that display MGRS/USNG. Just search for “MGRS”
> A 1 Km grid square is ~250 acres
> A 100 meter grid square is ~ 2.5 acres
> Map & compass are the minimum land navigation tools. Always have them with in the field. With the links provided in this article, you can now make your own gridded maps
> Gridded maps and USNG may be used for routine meeting locations and multiple non-emergency functions. They are a tool for the toolbox.
> GMap4 works without internet connection if maps are loaded prior to loss of connectivity
In summary, it is recommended that hikers routinely know their 1 Km, 100 meter or 10 meter grid square as applicable for task at hand. When breaking for water or lunch plot your position or at least look it over on your device(s). If the need arises, then when calling for help, advise your position early & quickly in case the call terminates early. If the call holds, then get more detailed as the call proceeds. Never hang up on a dispatcher / call-taker, they may have multiple questions for you. The following is offered for consideration, “ This is John Smith, I am located in grid WP (whiskey papa) 827 883, I have a person with a broken lower leg, we need help. We have food and shelter but need extrication off this mountain. Again my specific location is US National Grid coordinate eighteen tango whiskey papa eight two seven five eight eight three eight”
Note: position 18T WP 8275 8838 was selected based upon terrain for this article and does not represent the actual position of the hikers in the VanLaer article.
Note: some links updated 12–9–2016. Since this article was first written, two FREE websites now exist that function without internet connectivity after first use. They are USNGAPP.org and FindMeSAR.com Any hiker carrying a smart phone in the woods should have these websites pre-loaded and at-the-ready. These sites are fully vetted.
Auxiliary information & links:
Hasty Map creation and other USNG Medium articles
Appalachian Trail GISsurfer map
…a map without a grid is just a picture !!!
Rev 2: 09–14–2019
