Map Reading and Field Craft
Map reading basics
Scale is map distance to ground distance. On 1:50,000, 1 cm on the map = 500 m on the ground. Know representative fraction, statement of scale and graphical scale, and conventional signs for roads, railways, rivers, bridges, temples, wells and contours.
The three norths are true, magnetic and grid, and magnetic variation is the angle between true and magnetic north. Grid references are four-figure (1 km square) or six-figure (100 m). Bearings are measured clockwise from north with a protractor or prismatic compass; the back bearing is the bearing ± 180°. On contours, closely spaced lines mean steep ground, widely spaced lines mean gentle ground, and the V of a contour points upstream in a valley.
Field craft
Camouflage and concealment defeat the seven recognisable signs: shape, shine, shadow, silhouette, smell, sound and movement - plus spacing. Field signals may be hand, whistle or radio. Judging distance uses appearance (a man's features at about 100 m), a unit of measure, or the average of the section. Section formations include single file, file, arrowhead, diamond and extended line. Also learn fire discipline, patrols, ambush and use of ground.
Worked example
A road measures 6 cm on a 1:50,000 map. Ground distance = 6 × 50,000 = 3,00,000 cm = 3 km (divide cm by 1,00,000). If the bearing to a temple is 060°, the back bearing is 060 + 180 = 240°. If the bearing were 300°, the back bearing is 300 − 180 = 120°.
Traps
Reading 1:50,000 as 1 cm = 50 m instead of 500 m. Adding 180° when the bearing already exceeds 180°. Believing widely spaced contours mean steep ground.