6.22 Properties and Principles

6.22.2 Define scale and the relationship between chart and earth distances. 

Scale

Scale is the ratio between a distance on a chart (map) and the corresponding distance on the Earth’s surface. It tells you how much the real world has been reduced to fit on the chart.

Example:

• A scale of 1:500,000 means 1 unit on the chart represents 500,000 of the same units on the ground.

  • 1 cm on the chart = 500,000 cm (5 km) on Earth

  • 1 inch on the chart = 500,000 inches (~7.9 miles) on Earth

Key point: The larger the second number in the ratio, the bigger the area on the chart, meaning less detail is shown.

(You can fit the whole North Island on a 1:1,000,000 scale chart, and the Bay of Plenty on a 1:250,000)

Relationship Between Chart Distance and Earth Distance

Formula:

• Earth distance = Chart distance × Scale factor

Example Calculation:

• If two towns are 4 cm apart on a 1:250,000 chart:
  • Earth distance = 4 cm × 250,000 = 1,000,000 cm = 10 km
   

6.22.4 Describe the appropriate use of: 

(a) NZ Aeronautical Charts; 

NZ Aeronautical Charts are official maps produced by the Civil Aviation Authority (CAA) or other approved agencies, showing airspace, navigation aids, terrain, obstacles, and other features relevant to flight in New Zealand.