S. 114 land nav Flashcards
what is a map named after
most prominent cultural or geographical feature. largest city on the map where possible
where is the sheet name located
center of upper margin and either right/left side of lower margin
what is a sheet # used for
reference # for that map sheet
the sheet # is found in what 2 places
upper right and lower left margin
what representative fraction does a scale offer
ratio of a distance on the map to the corresponding distance on the earths surface
where is the scale located
upper left margin after the series name and center of the lower margin
what is the purpose of the elevation guide
helps you rapidly ID major land forms
where is the elevation guide located
lower right margin
what does the declination diagram indicate
the angular relationship of true north, grid north, and magnetic north (located in lower margin)
bar scales are used to convert what
map distance to ground distance
where are bar scales located
center of the lower margin
the legend helps ID what
topographic symbols
where is the legend located
lower left margin
what are grid lines
straight lines intersected at right angles forming a series of squares
how do grid squares measure on the most common military map
1,000x1,000 meters
what is the basic map reading rule
read right the up
a four digit grid coordinate locates a point within how many square meters
1,000
a six digit grid coordinate locates a point within how many square meters
100
a 8 digit grid coordinate locates a point within how many square meters
10
what is true north
a line from any point on the earths surface to the north pole
how can true north be located at night
north star
when is true north utilized
when traveling without a compass
how is true north represented on the declination diagram
a line ending with a star
how is magnetic north indicated
north seeking arrow of lensatic compass
how is magnetic north symbolized on the declination diagram
a line ending with a half arrowhead
how is grid north indicated on the declination diagram
GN
what must be used to work with an azimuth measured from grid north
protractor
define hill
an area of high ground
how is a hill depicted on a map
contour lines forming concentric circles
define ridge
series of hills that are connected to each other near the top
define saddle
a dip or low point between two areas of higher ground
how is a saddle depicted on a map
hourglass or figure-eight shaped contour lines
define finger/spur
short, continuous sloping line of higher ground, normally jutting out from the side of a ridge or hill
how is a finger depicted on a map
U or V pointing AWAY from high ground (ground slopes down in 3 directions)
define DRAW
short, continuous sloping line of LOW ground normally cut in the side of a ridge or hill
how is a draw depicted on a map
U or V pointing TOWARD high ground
define depression
low point in the ground or a sink hole. surrounded by higher ground in all directions
how is a depression indicated on a map
closed contour lines that have tick marks pointing toward low ground
what does the cover contain on a lensatic compass
sighting wire and two luminous sighting dots for night navigation
how is the floating dial mounted
on a pivot
what does the floating dial consist of
magnetic needle, luminous arrow and the letters E (90º) and WEST (270º) printed on the dial
what are 2 scales on the floating dial
outer denotes MILS (black) inner denoted (degrees) red
MILS are normally used by what
arty, tank, mortar gunnery
what does a MIL express
size of an angle formed when a circle is divided into 6,400 angles with the vertex at the center
what formula is used to convert degrees to mills
multiply degrees by 17.78
6,400 ÷ 360 = 17.78
what is the purpose of the glass encasemnent
houses the floating dials and contains a fixed black index line
what is a bezel ring
device that clicks when turned. 120 clicks when rotated fully. 1 click 3º
where is the thumb loop attached
the base
what is the rear sight used for
lock the floating dial
why must the rear sight be opened greater than 45º
allow the floating dial to float free
what is the lens used for
read the floating dial
what is the angular difference between grid north and magnetic north called
G-M angle
how should G-M angle be rounded
nearest whole degree
how does location by inspection work
estimating your relation to several prominent features
why is it better to use two-point resection vs one-point
doesn’t rely on ability to accurately estimate
how far apart should two prominent features be when using two point resection
at least 30º but no more than 150º
