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PPL · EASA 061 · Charts
Measuring distance with the chart scale
On a 1:500 000 chart you measure 18.52 cm between two turning points. What is the distance in nautical miles?
Explanation
A scale of 1:500 000 means one unit on the chart is 500 000 of the same units on the ground. Work in one unit all the way, then convert to nautical miles at the end: one nautical mile is exactly 1 852 m.
Step by step
- Chart distance times the scale denominator: 18.52 cm × 500 000 = 9 260 000 cm.
- In metres: 9 260 000 cm ÷ 100 = 92 600 m (92.6 km).
- In nautical miles: 92 600 m ÷ 1 852 m = 50 NM.
Why not the other answers
- 93 is the distance in kilometres (92.6 km). The conversion to nautical miles is missing.
- 5 NM reads 9 260 000 as millimetres instead of centimetres, so the result is ten times too small.
- 172 NM multiplies the kilometres by 1.852 instead of dividing: that turns nautical miles into kilometres, the other way round.
Tip. On a 1:500 000 chart, 1 cm is 5 km, so 10 NM is about 3.7 cm. In the cockpit the scale line on the chart edge or a navigation ruler is quicker than any arithmetic.
Original questions written by FlightDesk Aero and aligned with the EASA syllabus. They are not questions from the official EASA exam bank.