GPS interference risks

[Tsun]

Hi everyone,
I live in an area with warnings of possible GPS interference. I don't think situation is very serious, as the warnings have been ongoing for at least a few months, and I haven't seen any issues with navigation on my phone or heard about such from any of my friends, but I'm wondering what risks they may pose to a DJI drones. I understand that if GPS signal is lost mid air automatic RTH very likely won't work, but could the interference cause drone to crash or fly away in a random direction, or would I be able to bring it back manually? I have a Mavic 4 Pro with RC2 controller in case it's relevant.

 

[Meta4]

I understand that if GPS signal is lost mid air automatic RTH very likely won't work, but could the interference cause drone to crash or fly away in a random direction, or would I be able to bring it back manually?

If GPS is lost, your drone won't crash or fly off.
It would still be completely controllable, but won't have horizontal position holding ability.
It will hold altitude, but can drift with wind and it won't have any "brakes".

If you encounter GPS spoofing, that is quite different.
That transmits false GPS location data and there are cases of drones flying off because they suddenly think they are hundreds of miles from the home point.
Maps of areas where GPS jamming is happening are available.
Here's one GPSJAM GPS/GNSS Interference Map

 

[Tsun]

I think outside of Ukraine, it's mostly GPS jamming going on, not spoofing, right? ATC warnings for my area only talk about 'interference'.
Also, if drone thinks it's very far away from home, why would it fly away? I get it could try to initiate RTH/landing if battery level is considered insufficient, but it still should be controllable.

 

[Droning on and on...]

As meta4 says, you will lose positioning capability (which includes position hold) if above the VPS sensing range, usually above 30-45ft. This means the drone will drift with the wind, and will fly like a hockey puck on ice -- momentum will continue to carry it in the direction of travel when you center the sticks.

You will still be able to fly it just fine, but you will have to navigate strictly by visual information from the camera. Assuming you're VLOS compliant, it should be very easy to get back to the Home Point. If there is sufficient clearance around the HP (like a parking lot, field, etc.) you an descend to VPS range as soon as practical and regain position hold functionality, which will aid in bring it over to you for the final stretch, and more easily landing.

If you DO lose GPS don't wait... get it back to you and land as soon as possible. It will be blowing with the wind, and can quickly get out of sight, and hard to navigate back if you're not pretty familiar with the area you're flying in.

 

[Meta4]

I think outside of Ukraine, it's mostly GPS jamming going on, not spoofing, right? ATC warnings for my area only talk about 'interference'.

I don't know ... what area are you talking about?

Also, if drone thinks it's very far away from home, why would it fly away? I get it could try to initiate RTH/landing if battery level is considered insufficient, but it still should be controllable.

Low battery RTH happens when the drone has just enough battery power remaining to make it back to the home point.
Users in Cyprus reported their drones flying off when they were getting fake GPS signals putting their location in Lebanon.
I heard of similar reports from Poland, but haven't seen the flight data to get a better idea of what was happening.

 

[JoeShmoe]

Hi everyone,
I live in an area with warnings of possible GPS interference.

Could be GPS spoofing. If that's the case, the drone will fly away. Suggested remediations are: switch the drone into ATTI mode (if drone has one); lower altitude; monitor spoofing before taking off.

 

[jaja6009]

If you have an Enterprise drone, it's a good idea to switch into Atti (Attitude) mode to practice flying without GPS. We do this as part of our training and prefer to do so on windy days. With some practice it is possible to learn to hover somewhat reasonably and to land.

This conversation has reinforced this training for me and we will probably do this more often and also emphasize trying to recognize GPS loss or spoofing making the RPIC enter Atti mode to stop a possible GPS spoofed flyaway. We are in an area with these situations being a low risk, but it is better to start this knowledge earlier than later.

 

[Tsun]

I don't think Mavic 4 Pro has ATTI mode, but I agree it would be a good idea to have it just for such cases. I hope DJI enables it in consumer drones given the growing probability of GPS issues.
In any case, I have some experience from 'dumb' drones without GPS in the first place, I'm no stranger to compensating for wind and momentum. I'm mostly concerned about DJI software going haywire if the drone suddenly thinks it's in the middle of Siberia or has GPS reports completely different position than GNSS, but I guess there's no way to know until it happens.