Wind, Groundspeed, Time and Distance

Unless the wind blows straight down the course, it pushes the airplane sideways off track. To hold the desired ground track you turn slightly into the wind by a wind correction angle. That same wind also changes how fast you cross the ground: a headwind component reduces groundspeed and a tailwind component increases it. You solve the wind correction angle and groundspeed together, using a flight computer or by drawing the wind triangle. Once you know groundspeed, time-speed-distance falls out: time equals distance divided by groundspeed, so a 60-nautical-mile leg at a 120-knot groundspeed takes 30 minutes. These leg times feed directly into fuel planning, because fuel required is flight time multiplied by the burn rate from the performance charts. Drill the arithmetic until it is automatic, because the exam asks it plainly: at 90 knots groundspeed, 45 nautical miles takes 30 minutes (distance divided by groundspeed, times 60 for minutes); a 10 gallon-per-hour burn over 2.5 hours needs 25 gallons before reserves; and a diversion is the same problem started fresh — estimate the new heading toward the alternate, then compute time and fuel from the measured distance and current groundspeed. Testing Supplement wind-triangle and plotter tasks are the same computation with the numbers read from a figure. A wind estimate that is too optimistic makes every downstream number — time and fuel — wrong.