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Kp index for drone pilots: when a geomagnetic storm affects your flight
The Kp index shows how much the Earth's magnetic field is disturbed by solar activity. It runs from 0 to 9 and is worked out every three hours. For drone pilots it matters for two things: satellite navigation accuracy and the compass.
What the numbers mean
| Kp | What is happening | For your flight |
|---|---|---|
| 0–3 | Quiet | Normal conditions. |
| 4 | Raised activity | Small GPS fluctuations are possible, stay alert. |
| 5 | Minor geomagnetic storm (G1) | Fly carefully, close and within sight. |
| 6–7 | Moderate to strong storm (G2–G3) | Noticeable position errors and compass problems are possible. |
| 8–9 | Severe to extreme storm (G4–G5) | Consider putting flights off, especially precision work. |
How a geomagnetic storm affects a drone
- GPS accuracy. A storm disturbs the ionosphere that satellite signals pass through. The position can drift, and in strong storms errors reach several metres.
- Compass. Fluctuations in the magnetic field can throw off the drone's compass: while hovering it may sway or circle.
- Latitude. The further north, the stronger the effect, so in the Nordic and Baltic countries storms are felt more than in southern Europe.
What to do when Kp is high
- Kp 4 – fly as usual, but watch the satellite count and how the drone behaves.
- Kp 5 or more – fly close and within sight, keep a margin and be ready to fly without GPS.
- Put off work that needs a precise position: mapping, or inspections along a pre-planned route.
- Calibrate the compass only when the drone asks for it, and away from metal.
Kp is forecast a few days ahead, but less precisely than the weather: a storm can start earlier or later than expected.
Where to see the Kp forecast
Drone Wind shows the Kp index for every hour together with the wind, clouds and other conditions. During a geomagnetic storm the app warns you, and the answer is no better than Caution.
The app also helps you check drone zones anywhere in the world: in Lithuania, Estonia, Sweden, Norway and Austria the official drone zone map opens right at the place you choose, in 26 more European countries the official country map or information, and elsewhere a worldwide map. More about drone zones
Frequently asked questions
What Kp is fine for flying a drone?
Kp 0–3 means normal conditions and Kp 4 means stay alert. From Kp 5 there is a geomagnetic storm: fly carefully, close and within sight.
Does the Kp index only affect GPS?
No. Besides satellite navigation accuracy, fluctuations in the magnetic field can also affect the drone's compass.
How often does Kp change?
Kp is worked out every three hours, so there are eight values a day. It is forecast a few days ahead.