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NAV 13

# Notes:

• 1)

Visibility may be reduced by factors such as cloud cover, high terrain to the east (affecting first light) or the west (last light), dust, haze, fog, etc. Do not assume it is automatically OK to take off at first light, or keep flying till last light – you must also have the minimum legal visibility (see VMC in the FRP section of this manual).

• 2)

Sunrise, sunset and civil twilight times for any date and any location are calculated for you on www.ga.gov.au/geodesy/astro, but you cannot use this in the exam!

# Conversions

You must know these conversions which are useful for ballooning: 1kg = 2.2 lbs 1NM = 1.85km Metres multiplied by 10 and divided by 3 gives feet.

Also useful: 5 statute miles = 8km Temperature in F minus 32, then divided by 9 and multiplied by 5, gives C See AIP or VFG for other conversions.

# Calculations

The calculations required in the NAV exam are fairly straightforward, however if you are one of the many people who do not find calculations easy, it may help to use the following ‘square’ system.

• 1.

Put each step of the question into simple terms, to be clear what you are trying to find out. Eg, ‘the balloon descends at 700 feet in 3 minutes, so how many feet will it descend in 11 minutes?’

• 2.

Write the figures into four corners of a square, putting an ‘A’ in place of the answer you want to find, as shown below. Make sure the units (eg feet and minutes) are the same in each line – don’t put minutes in one and hours in the other!

(feet)

(minutes)

700

3

A

11

3. Starting at A, move around the square (in either direction, it makes no difference). Take the first figure you come to, divide it by the next figure and multiply it by the third (you can use a calculator). So in this example,