Form, Direction And Distance On The Earth

Question 1

Define great circles and properties

Answer 1

Drawn on earths surfaces, plane passes through the centre of the earth. Splits the earth into two equal parts.

Properties:

• Largest circle that can be drawn on the surface of the earth.
• shortest distance between two points on earth
• each half circle from NP to SP is called meridian
• Meridian + Anti meridian = GC
  GC at 90º to earths axis is the equator.

Question 2

Define Small circles

Answer 2

Any circle on the surface of the earth that doesn’t have its plane passing through the centre of the earth.

Question 3

Define rhumb lines and characteristics

Answer 3

Line on the earth’s surface which cuts all meridians at constant angle

Meridians & equator are RL and GC

Flying on RL will following a constant TRK with reference to True North direction.

Question 4

Define parallels of latitude.

Answer 4

small circles that have their plane 90º to the earths axis, excluding the equator.

Question 5

Define meridians of latitude

Answer 5

Great circles which pass through both geographic poles.

Question 6

Define Greenwich (prime) meridian

Answer 6

The meridian passing through green which is set at 0º longitude.

Question 7

Define relative bearing

Answer 7

Measured from the nose of the aircraft clockwise.

Question 8

Define back bearing

Answer 8

Relative bearing +/- 180º. RB is from own ship to target, BB is from the target to own ship.

Question 9

Explain the processes, cautions and limitations when deriving track distances and bearings from a chart.

Answer 9

Variation east, magnetic least. Variation west, magnetic best.

Deviation east, compass least. Deviation west, compass best.

HDG + RB = BT

Question 10

Various units used?

Answer 10

Visibility - m or km
Speed - knot
1m - 3.281ft
Altitude - feet
Distance - nautical mile