Wind Triangle Calculator
Calculate groundspeed using the wind triangle — accounting for TAS, wind direction, and wind speed to find your actual groundspeed.
Results
What is it?
The wind triangle is a vector diagram that relates true course, true airspeed (TAS), wind direction/speed, and groundspeed. By resolving these vectors, pilots can compute their actual groundspeed for fuel and ETE calculations. A positive headwind component reduces groundspeed; a tailwind increases it.
How to use
1. Enter your desired True Course in degrees. 2. Enter your aircraft True Airspeed in knots. 3. Enter the forecast wind direction (the direction FROM which the wind blows) in degrees. 4. Enter the wind speed in knots. 5. Read off groundspeed and ETE per 100 NM.
Example scenario
Flying true course 090 (eastbound) at TAS 120 kts. Wind from 270 at 20 kts (direct tailwind). Groundspeed = sqrt(120^2 + 20^2 - 2 x 120 x 20 x cos(180)) = sqrt(14400 + 400 + 4800) = sqrt(19600) = 140 kts. ETE for 100 NM = 100/140 x 60 = 43 minutes.
Pro tip
A direct headwind or tailwind gives the pure wind component. Any crosswind angle reduces the effective groundspeed change but adds a wind correction angle. The maximum headwind effect occurs at 0/180 degrees; the maximum crosswind effect occurs at 90 degrees. Use the 1-in-60 rule: 1 degree of heading error results in 1 NM off track for every 60 NM flown.