Map Systems
30 October 1996
Instructor: Jason Dalton

[Training Synopsis by Jessica Bonnett]

TYPES OF MAPS

• What you have seen us use at training/on searches are USGS topo maps, but there are many other types of maps.
• There are three ways to get the earth (round) onto a flat surface (map)- these are called projections- cylindrical,azimuthal, and conical

Latitude/Longitude coordinates

• Latitude lines run east/west. A good example of a latitude line is the equator, the rest continue above and below it
• Longitude lines run north/south. Think of the Prime Meridian which is at 0 degrees
• Lat/Long coordinates are given in DMS (degrees, minutes, seconds) notation. One degree of a lat/long coordinate can be further broken down into minutes, 1 degree=60 minutes. Then, the minutes can be further broken down into seconds, 1 minute=60 seconds

Other Coordinate Systems

• ASRC Grid
  
  • Used on ASRC search and training maps.
  • Based on a grid overlay with an X & Y axis. Coordinates are assinged in the format: (map letter)(two digit horizontal component)(two digit vertical component). For example, point Alpha 2545 is 2.5 marks over and 4.5 marks up on map Alpha
  • Major tick marks are 1 kilometer apart<
  • ASRC coordinates are arbitrarily assigned based on how the overlay is positioned on a map. Without the original overlaid map, coordinates carry no information. (This allows secure transmission of location information over the radio.)
• LORAN-C
  
  • System used for marine & aeronautical maps. Very similar to lat/long.
  • Minutes and Seconds are converted into their comparable decimal value.
  • Examples:15 min 30 sec = 15.5 min, 3 min 40 sec = 3.666 minutes
• UTM Coordinates (Universal Transverse Mercatur)
  • these are blue tick marks on the edges of the topo maps
  • You must have the entire map (not an ASRC xerox) to be able to see these marks.

BRMRG/ASRC Maps

• 1 page of the Gazeteer equals 4 of our map folders in the locker
• Our acetate ASRC grid overlays are yellow because it allows us to see the forests (ie green areas) on the map easier after it has been copied.
• The map is always alligned to TRUE north
• Aeronautical Charts (for working with CAP). Take bearing off a designated site (signal tower, airport, etc) and then determine distance. Be sure to note whether the bearing is true or magnetic -- most aeronautical navigation is done with magnetic bearings.