This is not a one-off. The National Institute of Telecommunications (Instytut Łączności) has run a GNSS monitoring station in Gdańsk since January 2024. Its August 2026 analysis says that in May and June there was multi-hour interference across all GNSS bands on about 70% of days. Only 10% of days in May and 13% in June were completely clean. In the first 19 days of August, full-band interference showed up on 63% of days. The institute links it to electronic warfare in the Baltic region and expects it to last as long as that activity continues. According to the analysis, recreational and commercial drone flights in these conditions are extremely risky, because the link can drop suddenly and the drone can lose position stabilisation.
If you fly on the coast, you need a plan for the day your drone stops knowing where it is.
Jamming and spoofing are different problems
Satellite signals are very weak by the time they reach the ground, so they are easy to drown out or fake.
Jamming is noise on the GNSS frequencies. The receiver loses the satellites, takes a long time to get a fix or stops giving a position at all. It is the louder of the two: the drone usually knows it has no GPS and tells you.
Spoofing is a fake signal that looks like the real one. The receiver keeps producing a position, it is just the wrong position, and often nothing on screen warns you. Prof. Mariusz Figurski from the institute put it this way: jamming is like someone removing all the road signs, spoofing is like someone swapping them. EASA makes the same point in its safety bulletin SIB 2022-02R4 (July 2026): spoofing is harder to detect and carries more risk. The Baltic Sea is on its list of affected areas.
One more detail matters for drones. The institute says the interference hits all GNSS systems at once, not just GPS. A receiver that also uses Galileo, GLONASS and BeiDou does not get you out of trouble here.
What a GPS drone does when the satellites go
The DJI Mini 4 Pro manual describes it well, and other GPS drones follow a similar logic.
In Normal mode the drone holds position from GNSS. When GNSS is weak but there is enough light, the downward vision system takes over. When neither works, or the compass is disturbed, the drone switches to ATTI mode. In ATTI it cannot hover or brake on its own and drifts with the wind. The manual tells you to land as soon as possible. The aircraft status light blinks yellow slowly in this mode.
Three details from the same manual matter on the coast:
- Vision positioning works best between 0.5 and 30 m above the ground and may not work properly over water. Exactly the place where you most need it.
- With a weak signal from power-on, the drone limits altitude to 30 m above the takeoff point (in poor light, with the infrared sensor working, it can be just 2 m). The limit disappears once the drone has seen a GNSS signal strength of at least 2 since power-on.
- The home point is recorded the first time the signal is strong or moderately strong, and the drone does not update it while the signal is weak. In failsafe RTH the drone may enter ATTI and land automatically if positioning is abnormal. For the Mini 3 the manual says plainly that RTH is not possible with a weak GNSS signal, and in ATTI intelligent flight modes and RTH are unavailable.
Put this together for a flight over the beach. If the signal disappears 200 m out over the water, you get no hover, no vision positioning and no working return to home. You get wind and your thumbs. If someone spoofs the signal instead of jamming it, the drone may decide it is somewhere else entirely and "correct" its position by flying off.
FPV with GPS Rescue
An FPV quad flown in Acro mode does not use GPS to stay in the air, so losing satellites does not change how it flies. The trouble starts with GPS Rescue and position hold.
Betaflight protects you against jamming quite well. With GPS Rescue configured, the quad needs a minimum number of satellites and a 3D fix to set the home point and arm (the default is 8, the wiki prefers 10). During a rescue, if the count drops below half that minimum for a total of 10 seconds, the sanity check fails and the quad disarms instead of wandering off.
Spoofing is a different story. The wiki says it directly: false or erratic GPS data may send the craft the wrong way without any way of knowing. A spoofed receiver reports plenty of satellites and a tidy position, so the sanity checks have nothing to catch.
What you can do on a coastal day:
- Check before takeoff that the satellite count is stable, and that speed and altitude in the OSD are not jumping while the quad sits on the ground. The Betaflight wiki recommends this as a basic check and says it can take another 30-60 seconds for the values to settle. The PDOP readout (
osd_gps_sats_show_pdop) helps too. - After takeoff, watch the home arrow. If it points the wrong way while you are flying straight away from yourself, do not count on the rescue.
- Think about whether GPS Rescue still makes sense as the failsafe on days of heavy interference. Over water, GPS Rescue that flies the wrong way and a plain motor stop end the same. Over land, a quad wandering off on false data can be worse than a drop. There is no single right answer here, but you should choose consciously before the flight, not after.
- Over water, check the Stage 1 failsafe throttle. It should make the quad climb steadily. The wiki warns that with a value too low, the quad may descend into the water in the one second before GPS Rescue kicks in.
Check the conditions before you go
Two public maps are worth a look before a trip to the coast.
RTGMS (rtgms.pl) is the Polish real-time GNSS monitoring system, built by the National Institute of Telecommunications with the Head Office of Geodesy and Cartography as part of the ESA NAVISP programme. It has been running since November 2025 and uses ASG-EUPOS reference stations around the country. Detected anomalies are shown on maps and charts. Because the stations are on the ground, it gives a better picture of what your drone will see than an aircraft-based map.
GPSJAM (gpsjam.org) builds its map from navigation accuracy reports broadcast by aircraft via ADS-B. Each day covers 24 hours in UTC and updates after midnight UTC. Green means under 2% of aircraft reported low accuracy, yellow 2-10%, red over 10%. The FAQ lists the limits honestly. Aircraft fly high and see more jammers than you do on the ground. A short burst of interference can turn a hexagon red even if GPS worked fine most of the day. And the map is not proof of jamming. Treat it as a regional hint, not a forecast for your field.
A red hexagon over Gdańsk does not mean your drone will fall out of the sky, and a green one is not a guarantee either. On the coast, just assume the interference may show up at any moment.
Practical rules for coastal flying
- Wait for a proper fix before takeoff. With a DJI, wait for the home point to be recorded, then compare the drone's position on the map with where you are actually standing. A drone placed on the water or a few streets away is a sign of spoofing. Do not take off.
- Keep it close and low. Fly so that you can always land manually within sight. The Wylatani summary of the institute's warnings recommends limiting distance and altitude to keep the drone in visual line of sight.
- Do not fly over water when it is not needed. Over the sand you lose a drone. Over the sea you lose a drone you can never recover.
- Practise flying without position hold. If your drone has an option to disable vision positioning (on the Mini 4 Pro: System Settings > Safety > Advanced Safety Settings), learn on a calm day over a meadow what a drifting drone looks like and how much stick it takes to hold it. Do this high enough and away from obstacles, and re-enable the option afterwards.
- Do not set up automated flights near the coast. The Mini 4 Pro manual warns not to use QuickShots and MasterShots with a weak GNSS signal. The same goes for waypoints and anything that relies on position.
- If the drone starts drifting, take control immediately. Do not wait for it to return by itself. Fly it back by eye or by the camera image, and land.
- Report the loss. If you lose control of the drone, report it straight away. In an August 2026 notice PAŻP listed what to tell the tower or FIS: approximate time until the battery runs out, the last known speed and altitude, and the direction of flight. Note these down as soon as anything goes wrong.