Use this page to revise Wind Triangle & Drift for the DGCA Air Navigation paper. Below are the key ideas first, then 12 practice questions with answers and explanations, picked from the 286 questions in the TrueHeading bank for this topic.
In short: Heading and TAS, track and ground speed, wind direction and speed.
Open the full set in the student zone to answer every question, track your accuracy and take timed mock tests.
Key concepts: Wind Triangle & Drift
8 ideas to know cold.
What are the six quantities in the wind triangle?
Heading and TAS, track and ground speed, wind direction and speed.
The vectors close: heading + wind = track
Drift is the angle between heading and track
WCA (wind correction angle) is the heading change needed to hold track: WCA = −drift
Wind direction is always where it blows from
How do you calculate the wind correction angle?
Use the sine rule on the wind triangle.
sin(WCA)=TASWsin(angle between track and wind)
Small angles: WCA ≈ 60 × crosswind ÷ TAS (degrees)
Wind from the right means crab right, so heading is to the right of track
How do you find headwind and crosswind components?
Resolve the wind against the runway or track.
Crosswind=Vsinθ
Headwind=Vcosθ
θ is the angle between wind direction and runway heading (or track)
Q5TAS 160 kt, required true track 130°, wind 330°(T)/40 kt. The groundspeed is approximately:
197 kt
217 kt
227 kt
118 kt
Show answer
Answer: A. 197 kt
GS = TAS × cos WCA − W × cos(wind angle) ≈ 197 kt.
Q6True heading 310°, drift 10° right. The true track made good is:
317°
330°
320°
324°
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Answer: C. 320°
Drift right: track = heading + 10° = 320°.
Q7An aircraft is to make good a true track of 060°. TAS is 320 kt and the wind is 160°/55 kt. What are the true heading and ground speed?
050° / 325 kt
050° / 315 kt
070° / 325 kt
070° / 310 kt
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Answer: C. 070° / 325 kt
WCA = asin(55/320 × sin(100°)) = +9.7° (wind from the right, so turn right into it). Heading = 060° + 9.7° ≈ 070°. GS = TAS × cos WCA − wind component along track ≈ 325 kt.
Q8An aircraft is to make good a true track of 315°. TAS is 250 kt and the wind is 240°/15 kt. What are the true heading and ground speed?
318° / 254 kt
312° / 246 kt
312° / 254 kt
318° / 246 kt
Show answer
Answer: B. 312° / 246 kt
WCA = asin(15/250 × sin(75°)) = −3.3° (wind from the left, so turn left into it). Heading = 315° − 3.3° ≈ 312°. GS = TAS × cos WCA − wind component along track ≈ 246 kt.
Q9TAS 430 kt, true track 270°, wind 160°/70 kt. The ground speed is closest to:
461 kt
360 kt
449 kt
500 kt
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Answer: C. 449 kt
Wind angle to track = 110°. WCA ≈ −8.8°. GS = 430·cos(8.8°) − 70·cos(110°) ≈ 449 kt.
Q10You wish to fly a true track of 275° at TAS 280 kt. The wind is 000°/25 kt. The true heading to steer is:
275°
280°
270°
290°
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Answer: B. 280°
The wind comes from the right of the track, so the heading is to the right of the track by the WCA of 5.1°. Heading ≈ 280°.
Q11TAS 360 kt, track 255°, wind 210°/55 kt. To maintain the track the aircraft heading must be about:
6° to the right of track
12° to the left of track
2° to the right of track
6° to the left of track
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Answer: D. 6° to the left of track
sin WCA = (wind speed / TAS) × sin(wind angle) → WCA ≈ 6°. Steer into the wind, i.e. to the left of the track.
Q12Runway 28 (magnetic 280°). Wind 320°/25 kt. The component along the runway on take-off is:
16 kt headwind
16 kt tailwind
19 kt tailwind
19 kt headwind
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Answer: D. 19 kt headwind
Angle between runway heading and wind = 40°. Along-runway component = 25 × cos 40° ≈ 19 kt, a headwind.