MapDrill

① Find the 1 km square containing the target. Read the easting on its left edge and the northing on its bottom edge. These give the first two digits of each coordinate.
② Place the grid reader’s red zero corner (top right) on the target. Read its top scale at the left grid line for the third easting digit. Read its right scale at the bottom grid line for the third northing digit. Each division is 100 m.
③ Estimate tenths of a division for the fourth digit (10 m).
④ Write 4 easting digits, then 4 northing digits. Read right, then up.

Use the first two easting and northing digits to find the 1 km square. Use the remaining digits to locate the point within it: 100 m, then 10 m. Answers within about 50 m are accepted.

1. For this map: magnetic bearing − westerly G–M angle = grid bearing.
2. Add or subtract 180° (3,200 mils) to get the back bearing.
3. Draw a line from each landmark along its back bearing.
4. The lines intersect at your position. Read the grid reference.

1. Align the compass sight line with landmark ① and read the magnetic bearing.
2. Subtract the westerly G–M angle to get the grid bearing. Add or subtract 180° (3,200 mils) for the back bearing.
3. Plot the back bearing from ①. Repeat for ②.
4. Read and enter the grid reference where the lines intersect.