38.30 Relative Velocity

38.30.2 Calculate the closing/opening speeds of two aircraft on the same track.

To calculate the closing or opening speeds of two aircraft on the same track, you need to know their respective groundspeeds and whether they are moving towards or away from each other.

1. Identify the Groundspeeds:

Let's say Aircraft A has a groundspeed of V1 knots and Aircraft B has a groundspeed of V2 knots.

2. Determine the Direction:

- If both aircraft are moving towards each other, the closing speed is the sum of their groundspeeds.

- If both aircraft are moving in the same direction, the opening speed is the difference between their groundspeeds.

3. Calculate the Speeds:

- Closing Speed = V1 + V2 (if moving towards each other)

- Opening Speed = |V1 - V2| (if moving in the same direction)

For example,

if Aircraft A has a groundspeed of 150 knots and Aircraft B has a groundspeed of 120 knots:

- If they are moving towards each other, the closing speed would be:

Closing Speed = 150 + 120 = 270 knots

- If they are moving in the same direction, the opening speed would be:

Opening Speed = |150 - 120| = 30 knots

38.30.4 Calculate the distance between two aircraft when they are 10 minutes apart on the same track.