GCSAR Navigation -- Maps

Transcription

1 GCSAR Navigation -- Maps

2 From the GCSAR Certification Standards Identify and explain all the border information on a topographic map. Identify and explain the following aspects of maps: index and intermediate contour lines and intervals, grid north vs. magnetic north, common symbols. Determine an approximate distance between two points on any map.

3 Top left and top right corners of a topo map Why are 1:24,000 Topo Maps called 7.5 minute maps? What is the latitude at the bottom of this map?

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9 Index and Intermediate Contour Lines Contour interval (in this case 40 ft) will be indicated on map

10 New US Topo Maps Just as ICS is now a part of NIMS, US Topo is now a part of The National Map. New US Topo maps are delivered digitally and have several layers, including an Orthoimage layer.

11 New US Topo Maps WGS 84 Stripped down base map (Corrected!! Sorta) Incorporates layers for streets, waterways, satellite image, etc. Updated every 3 years (Utah in 2017) Free Digital PDF files, with paper maps available for $15 ea.

12 2014 US Topo Map Good ol USGS Topo Map

13 2017 US Topo Map Good ol USGS Topo Map

14 2014 US Topo Map Good ol USGS Topo Map

15 2017 US Topo Map Good ol USGS Topo Map What happened to Maloy Park? Upper Porcupine Slickrock?

16 Let s check out a US Topo map.

17 From the GCSAR Certification Standards Explain horizontal datum and how it can affect the transfer of data between a GPS and map.

18 Where is UTM X ? GCSAR Manual error: Page 45, #20

19 From the GCSAR Certification Standards Define and identify the following common grid systems on any map in the GCSAR map packet: Geographic Coordinate System (Lat-Long) Universal Transverse Mercator (UTM) United States Public Land Survey System (Township, Range, Section) When given coordinates in any of the 3 common grid systems, locate that position on a map. Determine coordinates for any point on a map in each of the 3 common grid systems

20 Geographic Coordinate System You are Here

21 Do it in your head or at least on your calculator. Since we get D.d coordinates from dispatch, it would be useful to know how to convert those coordinate to D.M.S. for easier use on a USGS 7.5 Minute topo map. Convert to D.M.S. Multiply X 60 to get Minutes = (for aircraft) Now multiply.03 X 60 to get Seconds = = Since 1 second of latitude equals about 100 feet, we can round off to 2 seconds and only be 20 feet off.

22 Dispatchers sometimes say negative 109. That is not really necessary. But the identical coordinates with a + sign before the 109 will put you in the Ordos Desert 22 miles northwest of Yulin, China. Never vacation there with your dog on the Summer Solstice!

23 From GCSAR s Standards: Explain the difference between the 3 formats within the Geographic Coordinate System and their common uses. Degrees, Minutes, Seconds: This can be the most cumbersome format with which to work. It's a lot like telling time. There are 60 seconds in a minute and 60 minutes in a degree. So one quarter (.25) of a minute is 15 seconds. The only decimal point in this format might appear as a fraction of a second. However, tenths of a second are seldom crucial since a full second is roughly feet. On most GPS units, this will appear as hddd mm'ss.s". Degrees and decimal degrees: This is the standard format for e911 systems, OnStar, SPOT and InReach, and now GCSAR. There are no minutes or seconds in this format, only decimal fractions of a full degree. The number of digits to the right of the decimal point varies. On most GPS units, this will appear as hddd.dddd. Degrees, Minutes and decimal minutes: This is the preferred format for aircraft. There are no seconds in this format, only degrees, minutes, and decimal fractions of a minute. On most GPS units, this will appear as hddd mm.mmm'.

24 UTM Zones NPSAR and SPSAR cannot use UTM because it only extends from 80 degrees South to 84 degrees North

25 11S 13S The Central Meridian in each zone is given a value of 500,000. Easting is in relation to that meridian. Northing refers to meters North of the Equator

26 It s much easier to read accurate UTM coordinates on a topo map than it is to read accurate lat-long coordinates. When might we want to use UTM?

27 Latitude 40º MOAB SINGLETRACK map Features UTM and Dº M.m 38º You should be able to recognize which coordinate systems appear on any map 38º 45

28 Townships are approximately 6 miles square with boundaries conforming to meridians (longitude) and parallels (latitude) as closely as possible. Each Township is typically divided into 36 one-square-mile sections In the above example, the general PLSS description for the La in Lake would be SW ¼, SW ¼, SW ¼, Sec. 14, T2S, R3W. In Utah, this is measured from the SE corner of Temple Square. (SL B&M)

29 Broken Arch NW ¼, NW ¼, Sec. 35, T 23S, R 21E

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31 U.S. National Grid Reference System Your government at work! A confusing alphanumeric referencing system derived from the Military Grid Reference System where the higher value UTM numbers in the map margin are replaced with letters. You are here: XH The 100,000 meter UTM grid numbers (05, 06, 42, 43 in Grand County) become letters. UTM x (EOC) becomes XH X is the 06, H is the 42, followed by easting of and northing of We won t use NGRS until we are forced to do so, but you need to be able to recognize NGRS coordinates.

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