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Two aircraft depart from the same location and at the same time. Both follow a rhumb line track on latitude 83°N but they are flying opposite directions. One aircraft is flying to the east and its speed is 160 kts, and the other one is flying to the west with a speed of 120 kts. Time of departure is 10:20 UTC. At what time they will meet again?
  • A
    14:22 UTC
  • B
    13:52 UTC
  • C
    15:02 UTC
  • D
    19:44 UTC

The aircrafts are flying along the small circle at 83°N. Let’s start by finding the distance they will cover:

Departure = Change in Longitude (degrees) × 60 × cos latitude
Departure = 360 × 60 × cos 83
Departure = 2632 NM

The next step is to find the time it takes to cover the distance of 2 632 NM. Since we have two aircraft we can simply add their speeds: 120 kt + 160 kt = 280 kt.

Total speed: 280 kt
Distance: 2 632 NM
2 632 NM will be covered after 9 h 24 minutes (2 632 / 280)

  • If both aircraft depart at 1020 UTC they will meet again after 9 hours and 24 minutes which is at 19:44 UTC.

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