Aircraft Speed Test — Ground Speed & Flight Data via GPS
Measure aircraft ground speed using your phone's GPS. Works for GA, ultralights, gliders, and experimental aviation.
Shows: Ground speed · Max speed · Avg speed · Altitude · Heading · Distance
Works on iPhone, Android, and tablets. Place near window for best signal.
What This Tool Does
Turns your phone into a GPS flight speed meter. No app store. No pairing with avionics.
- ✓Ground speed via GNSS satellites
- ✓Heading in degrees
- ✓GPS altitude (not pressure altitude)
- ✓Distance traveled in nautical miles
- ✓Works offline after initial load
This measures ground speed. Not indicated airspeed. GPS can't read a pitot tube.
IAS vs TAS vs Ground Speed
Aviation uses different speed definitions. Know what you're looking at:
| Term | What It Means |
|---|---|
| IAS | Indicated Airspeed. What your airspeed indicator shows. Comes from the pitot tube. |
| TAS | True Airspeed. IAS corrected for altitude and temperature. Your actual speed through the air. |
| GS | Ground Speed. Speed over the ground. What GPS measures. Affected by wind. |
At 10,000 feet, 100 knots IAS is about 115 knots TAS. Add a 20-knot tailwind and your GS is 135 knots.
Who Uses This
- Student pilots
Learning to correlate ground speed vs indicated airspeed. Seeing wind effects in real time.
- Ultralight and LSA operators
Verifying true cruise performance. Marketing specs vs what you actually get.
- Glider pilots
Tracking glide efficiency. Comparing sink rates and distance covered in different conditions.
- Experimental builders
Validating performance claims. Testing modifications. Building a flight log.
- Drone operators
Checking FPV quad speeds. Verifying fixed-wing drone performance.
Typical Aircraft Ground Speeds
Reference values to check your readings (no wind, standard conditions):
| Aircraft Type | Cruise GS | Max GS |
|---|---|---|
| Paramotor | 35–50 km/h | ~60 km/h |
| Ultralight | 65–95 km/h | 110–120 km/h |
| Light Sport Aircraft | 90–130 km/h | 160 km/h |
| Cessna 172 | 180–200 km/h | ~230 km/h |
| Cirrus SR22 | 280–310 km/h | ~340 km/h |
| King Air (Turboprop) | 480–540 km/h | ~600 km/h |
| Regional Jet | 750–820 km/h | ~850 km/h |
| Airliner (B737/A320) | 850–900 km/h | ~945 km/h |
| FPV Racing Drone | 120–180 km/h | 250–300 km/h |
Wind Changes Everything
The basic formula every pilot knows:
Ground Speed = True Airspeed + Wind Component
| Condition | TAS | Wind | GS |
|---|---|---|---|
| No wind | 120 kts | 0 | 120 kts |
| Tailwind | 120 kts | +25 kts | 145 kts |
| Headwind | 120 kts | −25 kts | 95 kts |
This is why London to New York takes 8 hours but the return is only 6. Same airplane, same TAS. Jet stream makes the difference.
Where GPS Speed Works
- GA aircraft (Cessna, Piper, Diamond)
- Ultralights and LSAs
- Gliders and sailplanes
- Paramotors and trikes
- Drones and RC planes
- Helicopters
- Airliners (window seat)
- Fighter jets (too fast for phone GPS)
- Pressurized cabins without window
- Faraday-shielded military aircraft
- Aisle seats deep in cabin
GPS Accuracy in Flight
Accuracy depends on where you put the phone and how you're flying:
- Straight and level cruise
Best accuracy. Stable satellite lock. Doppler velocity is reliable at 300+ km/h.
- Phone near window
Essential. Glass passes GPS signals. Metal fuselage blocks them.
- Steep turns and maneuvers
May lose satellites briefly. Readings stabilize after rollout.
- Turbulence
Minor signal instability. Smoothing filter handles most of it.
Typical accuracy: ±1–3 km/h at cruise. Phone GPS uses Doppler shift at speed, which is more reliable than position sampling.
About GPS Altitude
GPS altitude is not the same as pressure altitude:
- 📡GPS altitude: Height above WGS84 ellipsoid. Derived from satellite geometry.
- 🌡️Pressure altitude: Height from barometric pressure. What your altimeter shows.
The difference can be 50–100 meters depending on location and atmospheric conditions. For terrain clearance and ATC, always use certified instruments. GPS altitude here is informational only.
Device Support
- iPhone
Excellent GPS. Multi-constellation GNSS works at altitude.
- Android
Strong performance. Qualcomm GNSS chips are reliable.
- iPad / Android Tablets
Works well. Larger screen is easier to read in cockpit.
- Laptops / Desktops
No GPS hardware. Won't work.
Frequently Asked Questions
Does this show indicated airspeed?+
Does altitude affect GPS speed readings?+
Does this work offline?+
Can drones use it?+
Does it work on commercial flights?+
Why is my ground speed different from what the captain announced?+
Safety and Legal
- ⚠️Do not operate your phone while acting as PIC. Mount it or have a passenger monitor.
- ⚠️GPS does not replace certified instruments. This is for reference and curiosity only.
- 📱Phone mounts must be secure. Loose phones become projectiles in turbulence.
- 📋Phone usage may be restricted during certain flight phases. Know the rules.
Coming Soon
Technical Notes
- •GNSS refresh ≥ 1 Hz required
- •Speed via Doppler at cruise velocities
- •Altitude via GPS ellipsoid model (not pressure)
- •Distance via Haversine formula
- •Constellations: GPS, Galileo, GLONASS, BeiDou
- •Works offline after initial page load