Calculate aircraft ground speed (GS = TAS·cos(WCA) - WS·cos(WD - TC)), wind correction angle (WCA), true heading (TH), headwind/tailwind components, and flight time with the free Ground Speed Calculator.
592.6 mph • 953.8 km/h • WCA: 0.0° • True Heading: 090° • Tailwind: +65.0 kts
No drift correction
Steer heading
Tailwind assist
Direct inline wind
600 NM leg
954 km/h (265 m/s)
In aeronautical navigation and kinematics, Ground Speed (GS) is the actual horizontal velocity of an aircraft across the Earth's surface. Unlike airspeed (which measures movement relative to the moving airmass), ground speed is the vector resultant of the aircraft's True Airspeed (TAS) and the surrounding Wind Velocity (WS & WD):
The direction the nose points (True Heading) and the speed at which the aircraft moves through the air column.
The motion of the airmass over the ground, defined by the direction the wind blows from.
The true geometric ground path over the Earth (True Course) and the resulting ground traversal speed.
Summary of foundational trigonometric formulas governing the E6B flight computer:
| Aviation Metric | Trigonometric Formula | Units & Description |
|---|---|---|
| Wind Correction Angle (\(\text{WCA}\)) | $$\text{WCA} = \arcsin\left(\frac{\text{WS} \sin(\text{WD} - \text{TC})}{\text{TAS}}\right)$$ | \(\text{degrees } (^\circ)\) Crab angle |
| True Heading (\(\text{TH}\)) | $$\text{TH} = \text{TC} + \text{WCA}$$ | \(\text{degrees } (0^\circ - 360^\circ)\) |
| Ground Speed (\(\text{GS}\)) | $$\text{GS} = \text{TAS} \cos(\text{WCA}) - \text{WS} \cos(\text{WD} - \text{TC})$$ | \(\text{knots, mph, km/h}\) |
| Headwind Component (\(\text{HW}\)) | $$\text{HW} = \text{WS} \cos(\text{WD} - \text{TH})$$ | \(+\text{Headwind} / -\text{Tailwind}\) |
| Crosswind Component (\(\text{XW}\)) | $$\text{XW} = \text{WS} \sin(\text{WD} - \text{TH})$$ | \(\text{knots Left / Right}\) |
| Estimated Time Enroute (\(\text{ETE}\)) | $$\text{ETE} = \frac{\text{Leg Distance}}{\text{GS}}$$ | \(\text{hours, minutes}\) |
Choose between Wind Triangle Navigation, Distance & Time solver, or Indicated Airspeed (IAS) altitude conversion.
Input aircraft True Airspeed (in \(\text{knots}\), \(\text{mph}\), or \(\text{km/h}\)) and planned True Course (\(0^\circ - 360^\circ\)).
Enter winds aloft forecast data: the direction the wind blows from (\(^\circ\)) and wind velocity (\(\text{kts}\)).
Inspect calculated Ground Speed, Wind Correction Angle, True Heading to steer, headwind/crosswind splits, and live math proofs.
Understanding the 5 distinct speeds used in modern aviation:
Uncorrected dynamic pressure read directly from the pitot tube. Governs aerodynamic stall and flap limits.
IAS corrected for pitot-static position and instrument calibration error.
Actual speed relative to the undisturbed air column: \(\text{TAS} = \text{CAS} \sqrt{\rho_0 / \rho}\). Increases \(\approx +2\%\) per \(1,000\text{ ft}\).
Actual rate of horizontal movement across the Earth's surface: \(\vec{\text{GS}} = \vec{\text{TAS}} + \vec{\text{Wind}}\).
CAS corrected for high-speed adiabatic compressibility at transonic Mach numbers.
Ratio of True Airspeed to the local speed of sound: \(M = \text{TAS} / a\).
How prevailing jetstreams alter commercial flight schedules:
Polar and subtropical jetstreams routinely exceed \(100\text{ to }180\text{ knots}\) at cruising altitudes (\(\text{FL300-FL400}\)). When flying eastward from New York (JFK) to London (LHR) along course \(080^\circ\) with a \(120\text{-knot}\) tailwind, a Boeing 777 cruising at \(\text{TAS} = 490\text{ kts}\) achieves a blistering ground speed of \(\text{GS} = 610\text{ kts}\) (\(702\text{ mph} \approx 1,130\text{ km/h}\)), cutting flight time by over an hour. Conversely, westward return flights must navigate around headwind cores to avoid ground speeds dropping below \(370\text{ kts}\).
Solves exact law-of-sines and law-of-cosines flight computer navigation vectors.
Instantly isolates inline headwind/tailwind speed and lateral crosswind drift components.
Computes exact estimated time enroute in hours and minutes for flight planning logs.
Converts indicated cockpit airspeed to True Airspeed using pressure altitude and OAT.
Simultaneously reports outputs in knots (\(\text{kts}\)), miles per hour (\(\text{mph}\)), and \(\text{km/h}\).
Runs instantly on mobile, tablet, and desktop with zero server lag and complete calculation privacy.
Why drone operators must calculate ground speed before outbound flights:
Commercial quadcopters and survey fixed-wings have maximum airspeed limits (\(\text{TAS} \approx 30\text{ to }45\text{ kts}\)). If a drone flies outbound downwind at \(\text{GS} = 55\text{ kts}\), its return leg into a \(20\text{-knot}\) headwind drops ground speed to \(\text{GS} = 15\text{ kts}\), requiring \(3.6\times\) more flight time and battery capacity to return home. The Ground Speed Calculator prevents lost-link battery exhaustion.
How flight dispatchers calculate statutory legal fuel minimums:
Aviation regulations mandate that every flight carry sufficient fuel for the route plus reserve margins (FAA FAR 91.151: \(30\text{ min}\) VFR day / \(45\text{ min}\) VFR night; FAR 91.167: \(45\text{ min}\) IFR + alternate). Flight leg fuel is calculated directly from ground speed:
Calculating lateral drift forces during final approach and landing:
Pilots align the aircraft velocity vector along the runway centerline by maintaining wind correction heading: \(\text{TH} = \text{Runway Heading} + \text{WCA}\).
Prior to touchdown, ailerons bank the upwind wing into the wind while opposite rudder aligns the fuselage with the centerline to prevent side loading on the landing gear.
Why hot-and-high mountain airports dramatically lengthen takeoff and landing ground rolls:
Wings generate aerodynamic lift based on Indicated Airspeed (\(\text{IAS}\)). At high density altitude (e.g., Aspen at \(8,000\text{ ft}\) on a hot \(30^\circ\text{C}\) day), an aircraft must achieve a substantially higher True Airspeed (\(\text{TAS} = \text{IAS} \sqrt{\rho_0 / \rho}\)) to generate the same lift. In calm winds, this elevates the liftoff Ground Speed by over \(25\%\), increasing the required takeoff ground roll distance by more than \(56\%\) (\(\text{Distance} \propto \text{GS}^2\)).
Calculating the inflight emergency turnaround decision boundary:
The Point of Equal Time (PET) is the position along a route where flight time to continue to the destination equals flight time to return to departure. In zero wind, PET is at route midpoint; with wind, it shifts toward the into-wind airport:
Determining maximum outbound flight distance with mandatory fuel reserves:
For safe fuel endurance \(T_{\text{safe}}\): \(t_{\text{out}} = \frac{T_{\text{safe}} \times \text{GS}_{\text{return}}}{\text{GS}_{\text{out}} + \text{GS}_{\text{return}}}\).
The maximum radius of action is \(D_{\text{PSR}} = t_{\text{out}} \times \text{GS}_{\text{out}}\). Beyond this point, the aircraft cannot return to the departure airport without exhausting reserves.
How pilots chain waypoint leg calculations into ATC flight plans:
A cross-country flight consists of multiple waypoints with varying winds aloft forecasts. By solving the wind triangle on each discrete flight leg, pilots determine the exact True Heading (\(\text{TH} = \text{TC} + \text{WCA}\)), apply magnetic variation to obtain Magnetic Heading (\(\text{MH} = \text{TH} \pm \text{Var}\)), and calculate accurate waypoint Estimated Times of Arrival (\(\text{ETAs}\)).
Comprehensive answers to common questions about aviation ground speed, wind correction angle, true airspeed, and flight planning.
