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An aircraft departs a point 04°00’N, 030°00’W and flies 600 NM south, followed by 600 NM east, then 600 NM north, then 600 NM west.

What is its final position?

  • A
    03°58’N, 030°02’W
  • B
    04°00’N, 029°58’W
  • C
    04°00’N, 030°00’W
  • D
    04°00’N, 030°02’W

To solve this type of question, it is important to be familiar with:

  • Departure (NM) = Change of Longitude (min) x cos Lat
  • One minute of latitude equals one nautical mile and degrees of latitude are 60 nm apart.

(1) From 04°00’N, 030°00’W ⇒ Aircraft flies southwards for 600 NM

1º Latitude = 60 NM
Therefore, 600 NM / 60 NM = 10º S

- After the first leg (southwards), the aircraft will be at 04º00'N - 10ºS = 06º00' S

  • 06º00'S 030º00'W

(2) From 06º00' S 030º00' W ⇒ Aircraft flies eastwards for 600 NM

600 NM = Change of longitude (min) x cos (06º00')
Change of longitude (min) = 600 / cos (06º00')
Change of longitude (min) = 603 min
Change of longitude (º) = 603 / 60 = 10º3' E

- After the second leg (eastwards), the aircraft will be at 030º00'W - 10º3'E = 019º57'W

  • 06º00'S 019º57'W

(3) From 06°00’S, 020°00’W ⇒ Aircraft flies northwards for 600 NM

1º Latitude = 60 NM
Therefore, 600 NM / 60 NM = 10º N

- After the third leg (northwards), the aircraft will be at 06º00'S + 10ºN = 04º00' N

  • 04º00'N 019º57'W

(4) From 04º00' N 020º00'W => Aircraft flies westwards for 600 NM

Start by using the Departure formula to find the change of longitude:

600 NM = Change of longitude (min) x cos (04º00')
Change of longitude (min) = 600 / cos (04º00')
Change of longitude (min) = 601 min

Change of longitude (º) = 601 / 60 = 10º1' W

- After the forth leg (westwards), the aircraft will be at 019º57'W + 10º1' W = 029º58'W

  • 04º00'N 029º58'W

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