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Determine the wind direction (ºM) and velocity, given:

OAT: +10ºC
Time overhead VOR 1: 12:10 UTC
Time overhead VOR 2: 12:18 UTC
Distance VOR 1 - VOR 2: 25 NM
Track VOR 1 - VOR 2: 355º(M)
CAS: 140 kt
Altitude: FL55

• A
135°M and 41 kt
• B
139°M and 49 kt
• C
139°M and 45 kt
• D
142°M and 43 kt

Refer to figures.

Convert CAS into TAS (CRP5 method):

(1) In the "Airspeed" window, align 5 500 ft with OAT = +10ºC;
(2) On the inner arc, look for CAS 140 kt and read a result of approximately 154 kt TAS.

Calculate the Ground Speed:

Ground Speed = Distance / Time
Ground Speed = 25 NM / 8 min = approx. 188 kt

Determine Drift:

There is a 10º difference between the track and the heading, which means that drift = 10º. Track is lower than heading, meaning it's a left drift (10ºL).

Determine W/V (CRP5 method):

1. Set Magnetic Heading (005ºM) under "True Index"
2. Place centre dot over TAS (154 kts)
3. Mark the point where drift (10ºL) and GS (188 kt) meet.
4. Rotate the wind computer until mark is below TAS.
5. Check wind direction under "True Index" (139º)
6. Count down from TAS to obtain wind speed (154 - 109 = 45 kt)

=> W/V = 139(ºM)/45 kt

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