Lost Drones

[Meta4]

Hi, the area I used for take-off was just an area of bitumen, away from nearby buildings, although relatively close to the power lines. I charge the drone battery near a speaker, but not adjacent.The take-off went as planned and I managed to take a shot I was after. The drone just then decided it was a question of seeing how fast it could crash.

After a previous incident, I am now really concerned about the risk of my drone hitting someone. I always aim to take off with no one within 50m, but if the drone does something erratic and - more worryingly ignores collision risk - it seems a threat to personal safety.

The problem was almost certainly due to launching from a magnetically compromised spot and not a fault in the drone.
You can prevent such things by avoiding launching from reinforced concrete surfaces or locations that might have steel pipes etc buried just below the surface, or locations very close to cars, steelwork etc.
You can also check the red arrow icon in the radar or map display is properly aligned with respect to compass directions ie, icon pointing west and the drone is pointing west.
If the icon is pointing in a different direction than the drone is, that's warning of a problem like what you saw in that flight.

I found another flight record (with a Mavic Pro) that was one where I lost control of the drone during RTH where the drone repeatedly went away from the RTH point.

The reason for this issue is clearly shown in the flight data: DJI Flight Log Viewer - PhantomHelp.com
Without GPS, your drone has no horizontal position holding ability and will drift on the wind.
It is unable to RTH without GPS.
You had a situation where GPS was lost a number of times during the flight, leaving the drone drifting in atti mode.
You still had full control but left the drone to drift each time.

5:27 - signal lost, drone is 410 feet away
5:43 signal regained, drone is in RTH and 226 ft away
5:45.3 GPS sats drop to zero for three seconds
5:52.1 GPS sats drop out again, drone defaults to atti mode 37 ft from home and 200 feet up.
Without GPS, the drone lacks horizontal positioning ability and has no brakes.
It drifts on the breeze 200 ft up.
GPS recovers at 6:18.8, drone has drifted to 98 feet away
You leave the drone there until 6:46 when you initiate RTH again.
6:48.1 GPS drops out again, drone drifts in atti mode
7:14.2 GPS regained, but GPS health is very poor (0), drone is 180 ft away
Full GPS regained at 7:32, RTH initiated at 7:35, GPS lost again at 7:39.3
Full GPS regained at 8:27.6, RTH at 8:32.6
Drone returns and starts descending, loses GPS again at 8:46.3

The reason for the repeated GPS loss is puzzling and it's not a common issue.
You don't seem to have flown under cover that would block satellite reception and GPS was perfect until 5:27.
I'll look a little more into a possibility and report back.

 

[Dr. Bill 1969]

I have had three bad experiences with Mavic drones in three weeks and am a bit baffled, and nervous about continuing with drones.

All three experiences happened in Switzerland. I have flown Mavic drones all over the world, but all three bad experiences happened in Switzerland.

First was with a Mavic Pro in Basel. I was trying to manually land the drone when it decided to fly off in another direction and hit somebody. Thankfully they were sanguine about the experience, but I wasn't. What if it had them in the head?

Second time was in Vevey with RTH. It didn't return to home, it flew off in a random direction and last i saw of it looked like it hit a stairwell on top of a block of flats. $1000 dollars of drone gone.

So I bought a Mavic 2 Zoom. Fabulous drone, great footage. Went to Ventoux to take video lost with the last drone and after hovering for me to take a pic, the drone just shot off randomly and hit a building a few hundred metres away - so much for collision detection. I couldn't control it at all, just had to watch as it totalled itself. Landed on a balcony and haven't been able to retrieve it, so that's another $1200 down the toilet.

Am I just unlucky or what? Is there something in the air in Switzerland? I am totally giving up on flying drones for a while, not just the expense but the feeling that I can't control my drones and - frankly - it seems they represent a risk to public safety.

The world's largest and most powerful particle accelerator is located just outside of Geneva Switzerland . The Hadron Collider creates magnetic pulses(although heavily shielded) which are easily measured as far South as Rome and West as Paris. You could have had the unfortunate "luck" of flying when the accelerator was operating. It's a long shot; but as the times of operation aren't classified you might inquire as to any correlation of your "misfortunes" and the accelerator's operation.

Bonne chance!



Their address:

• CERN
• Esplanade des Particules 1
• P.O. Box
• 1211 Geneva 23
• Switzerland

 

[Meta4]

The points where GPS satellites dropped out were as shown here:

Losing GPS satellite reception like this is very unusual.
I can only think of two possibilities (but maybe someone else has a different idea):

1. an intermittent hardware issue
2. a mysterious local GPS interference

Did the drone/GPS work properly before and after at other locations?
If so that probably eliminates #1
#2 would be very rare but I have seen reports of similar at a location in Moscow and another from somewhere else in Russia.

 

[sar104]

Here is the flight log. The drone ascended vertically fine then just took over control and flew off without me doing anything, crashing a few hundred feet away. I managed to retrieve the drone, but nervous about flying it again unless I can work out what happened.

Flight time	Altitude​	Home Dist	Type	Notification
	00m 00s	0.0 ft	0 ft	Mode	Mode changed to P-GPS
	00m 00s	0.0 ft	0 ft	Warning	Compass Error
	00m 00s	0.0 ft	0 ft	Mode	Mode changed to Motors_Started
	00m 00s	0.0 ft	0 ft	Tip	Setting new Return-To-Home altitude to 30m (98 ft). Data Recorder File Index is 7. Setting new Maximum Flight Altitude to 30m (98 ft)
	00m 01s	0.0 ft	0 ft	Mode	Mode changed to Assisted_Takeoff
	00m 04s	0.0 ft	0 ft	Mode	Mode changed to P-GPS
	00m 04s	0.0 ft	0 ft	Warning	Braking now. Return sticks to midpoints, then continue flying.
	00m 07s	15.1 ft	0 ft	Warning	Maximum Flight Altitude Reached. Adjust altitude in MC Settings if required.
	00m 08s	16.7 ft	0 ft	Tip	Setting new Maximum Flight Altitude to 120m (394 ft)
A	00m 13s	62.7 ft	0 ft	Mode	Mode changed to P-GPS
B	00m 17s	71.5 ft	3 ft	Tip	Home Point recorded. Return-to-Home Altitude:30M
C	00m 23s	78.1 ft	276 ft	Warning	Not Enough Force/ESC Error (repeated 34 times)
	00m 27s	65.6 ft	499 ft		97% Battery at maximum distance

It looks like a case of taking off from a magnetically distorted location causing an incorrectly initialized IMU yaw value. As I mentioned earlier, you can infer that error from the comparison of IMU velocity, compared to the time derivate of position computed from the sensor fusion algorithm:



Those are large discrepancies. This really needs the mobile device DAT file (FLY007.DAT) with the raw sensor data to confirm what happened.

Mobile device DAT file: How to retrieve a V3.DAT from the tablet

 

[AMann]

The world's largest and most powerful particle accelerator is located just outside of Geneva Switzerland . The Hadron Collider creates magnetic pulses(although heavily shielded) which are easily measured as far South as Rome and West as Paris. You could have had the unfortunate "luck" of flying when the accelerator was operating. It's a long shot; but as the times of operation aren't classified you might inquire as to any correlation of your "misfortunes" and the accelerator's operation.

Bonne chance!



Their address:

• CERN
• Esplanade des Particules 1
• P.O. Box
• 1211 Geneva 23
• Switzerland

That’s an intriguing theory, but he was more than 150 miles from Cern while in Basel, and Ventoux is in France.

 

[RickinWaST]

As a soon to be first time drone owner (Either refurbished M2Pro, M2Zoom, it new Platinum) this discussion had been enlightening!

 

[nicoatridge]

Hi, thank you for your really enlightening information. I am pretty certain that the problems were not caused by malfunctions in the drone(s) as they have both flown before and since quite predictably. I have to say I was quite spooked by these incidents. I am intrigued by the possibility that some sort of jamming device may have been deployed - is this physically possible? I cannot envisage what strong magnetic forces might be present in sleepy Ventoux, just outside Montreux, or how GPS could fail in somewhere as cosmopolitan as Vevey and Basel. Just to mention, after many hours of drone flying in North America and Europe, all my bad experiences happened in Switzerland. Incidentally, the flight were I lost GPS the local police arrived as I was landing and asked me some questions about my drone flight, which they said they had monitored. As far as I know I had not broken any ordinances or best practices in drone operation but the Swiss police are quite thorough in investigating anything that everything.

Incidentally, good news, the drone that I lost has been handed in to the police and I can pick it up. The other drone I managed to retrieve from a vineyard using the flight data and it looks fine even though it crashed at 60mph, - although I need to replace a couple of propellers.

I attach the DAT file from the flight where the drone just went and did it's own thing. Still intrigued why obstacle detection failed even allowing for magnetic forces being at play.

 

[Meta4]

I am intrigued by the possibility that some sort of jamming device may have been deployed - is this physically possible?

GPS jamming is possible, but it's very rarely imposed legally.
I'm not keen to suggest that was what caused the incident, but mentioned it as one possibility since I couldn't come up with a more likely cause.

I cannot envisage what strong magnetic forces might be present in sleepy Ventoux, just outside Montreux, or how GPS could fail in somewhere as cosmopolitan as Vevey and Basel.

The magnetic forces don't have to be particularly strong to cause a runaway flight like you saw.
It can be caused by relatively small-sized steel items, if they are very close to the compass when the drone is initialising.
Launching from reinforced concrete surfaces is the most common cause.
Did you have GPS loss issues on another flight?

The other drone I managed to retrieve from a vineyard using the flight data and it looks fine even though it crashed at 60mph, - although I need to replace a couple of propellers.

It would be interesting to see the data from that flight too.
Every incident helps contribute to collective knowledge.

Still intrigued why obstacle detection failed even allowing for magnetic forces being at play.

Sar104 could explain better but once the drone started running away, it was not capable of stopping or hovering in place.
Even if it could stop, at a speed of 56 mph the obstacle avoidance system could not give enough warning for the drone to stop before crashing.

 

[Dr. Bill 1969]

That’s an intriguing theory, but he was more than 150 miles from Cern while in Basel, and Ventoux is in France.

Remember, the Cern's electro-magnetic pulse can be easily read as far South as Rome and West to Paris. Given the Mavic's "black box" reveals a strong magnetic deviation our flyer may have been in exactly the wrong place at the wrong time. Rome is 541 "driving miles" from Cern...but then again it's only a theory.

 

[Meta4]

Given the Mavic's "black box" reveals a strong magnetic deviation our flyer may have been in exactly the wrong place at the wrong time.

The compass related issue in the first flight record posted is easily explainable by launching from close to a bit of steel.
It's unlikely to be related to any electro-magnetic pulse.
The second flight showed no compass issues and was a failure of GPS reception.

 

[sar104]

Hi, thank you for your really enlightening information. I am pretty certain that the problems were not caused by malfunctions in the drone(s) as they have both flown before and since quite predictably. I have to say I was quite spooked by these incidents. I am intrigued by the possibility that some sort of jamming device may have been deployed - is this physically possible? I cannot envisage what strong magnetic forces might be present in sleepy Ventoux, just outside Montreux, or how GPS could fail in somewhere as cosmopolitan as Vevey and Basel. Just to mention, after many hours of drone flying in North America and Europe, all my bad experiences happened in Switzerland. Incidentally, the flight were I lost GPS the local police arrived as I was landing and asked me some questions about my drone flight, which they said they had monitored. As far as I know I had not broken any ordinances or best practices in drone operation but the Swiss police are quite thorough in investigating anything that everything.

Incidentally, good news, the drone that I lost has been handed in to the police and I can pick it up. The other drone I managed to retrieve from a vineyard using the flight data and it looks fine even though it crashed at 60mph, - although I need to replace a couple of propellers.

I attach the DAT file from the flight where the drone just went and did it's own thing. Still intrigued why obstacle detection failed even allowing for magnetic forces being at play.

Well that's an interesting lesson, and the first example I've seen of defeating the M2 compass error correction algorithm by powering up the aircraft in a location with significant magnetic distortion and then moving it to an undistorted location before taking off. The M2 detects IMU yaw / compass yaw divergence on takeoff and resets the IMU yaw to match the new compass yaw but, in this case, the divergence happened 40 seconds before takeoff. By the time it took off there was already a disagreement of 145°, which completely accounts for that uncontrolled flight trajectory.




Other than that the IMU was working correctly. The M2 is far more robust at correcting for magnetic errors but this one it cannot deal with. In my opinion the aircraft should not be moved after power up unless absolutely necessary; that risks various problems but also, in particular, defeats this protection. @BudWalker - have you seen this with an M2?

I would be a little concerned about the GPS module though. While it worked okay tracking this flight, it was slow to acquire:



It did not have a position lock and P-GPS mode until 8.5 seconds after takeoff, not that it had anything to do with the uncontrolled flight.

And in the other log that you posted, as noted above, the GPS was behaving strangely:

 

[JohnC]

GPS jamming is carried out quiet regularly in Northern England due to a large tactical electronic warfare range occupying a large chunk of land between Newcastle and Carlisle. These trials are always in a NOTAM. Similar activities would be notified in Switzerland. It should also be noted that during times of tension Uncle Sam will degrade the GPS or disable it all together, it is not a guaranteed service but we have all come to expect it to be.

 

[wsteele]

GPS jamming is carried out quiet regularly in Northern England due to a large tactical electronic warfare range occupying a large chunk of land between Newcastle and Carlisle. These trials are always in a NOTAM. Similar activities would be notified in Switzerland. It should also be noted that during times of tension Uncle Sam will degrade the GPS or disable it all together, it is not a guaranteed service but we have all come to expect it to be.

Your last sentence is incorrect and misinformed. Yes, GPS is operated by the US Department of Defense and yes, when designed, the civilian signal could be intentionally degraded. However, with the implementation of WAAS which provided precise location corrections and the world wide adoption of GPS for safe commercial aircraft navigation, Selective Availability (SA) was turned off around the year 2000 and the US DOD has never since degraded or disabled the GPS signals. Essentnially the only degradations come from temporary satellite geometry errors {PDOP), loss of signals due to localized intentional or unintentional interference or physical blockage of signals by buildings etc. In 2007 the US formally adopted a policy that SA would never be used again and the current generation of GPS satellites were designed and deployed without the technology.

 

[stiller_paul]

I have had three bad experiences with Mavic drones in three weeks and am a bit baffled, and nervous about continuing with drones.

All three experiences happened in Switzerland. I have flown Mavic drones all over the world, but all three bad experiences happened in Switzerland.

First was with a Mavic Pro in Basel. I was trying to manually land the drone when it decided to fly off in another direction and hit somebody. Thankfully they were sanguine about the experience, but I wasn't. What if it had them in the head?

Second time was in Vevey with RTH. It didn't return to home, it flew off in a random direction and last i saw of it looked like it hit a stairwell on top of a block of flats. $1000 dollars of drone gone.

So I bought a Mavic 2 Zoom. Fabulous drone, great footage. Went to Ventoux to take video lost with the last drone and after hovering for me to take a pic, the drone just shot off randomly and hit a building a few hundred metres away - so much for collision detection. I couldn't control it at all, just had to watch as it totalled itself. Landed on a balcony and haven't been able to retrieve it, so that's another $1200 down the toilet.

Am I just unlucky or what? Is there something in the air in Switzerland? I am totally giving up on flying drones for a while, not just the expense but the feeling that I can't control my drones and - frankly - it seems they represent a risk to public safety.

You have been very unlucky. My Mavic never goes rogue. I used to have range issues. But, then I sent it out to have a post market antenna installed. It has done well since then. I still crash it. But, it's my fault. I never fly around people though.

 

[JohnC]

Your last sentence is incorrect and misinformed. Yes, GPS is operated by the US Department of Defense and yes, when designed, the civilian signal could be intentionally degraded. However, with the implementation of WAAS which provided precise location corrections and the world wide adoption of GPS for safe commercial aircraft navigation, Selective Availability (SA) was turned off around the year 2000 and the US DOD has never since degraded or disabled the GPS signals. Essentnially the only degradations come from temporary satellite geometry errors {PDOP), loss of signals due to localized intentional or unintentional interference or physical blockage of signals by buildings etc. In 2007 the US formally adopted a policy that SA would never be used again and the current generation of GPS satellites were designed and deployed without the technology.

Thanks for the clarification, however the WAAS is not available outside of USA/Mexico area, the European system of an augmentation system is still being developed.

 

[Racin8de]

It's never been a daily occurrence.
There's no such thing as a "flyaway".

You have to be very impatient to launch before recording a home point.
But if you did, the drone would acquire GPS very soon after launching and record a home point when it gets good GPS location data.
And that would not cause anything like what the OP described.

LOl, here we go... Yeah there USED to be things called flyaways and YES it was a daily occurence not with just the Phantoms back in 2013 but with the Blade 350 QX's, The Walkera QRX350 or whatever it was... Bud this ain't my first day!

 

[Racin8de]

Here's the story of the crash. It's a new drone. Worked fine on Saturday. Became possessed on Sunday...View attachment 79466

worked fine on Saturday became possessed on Sunday.. LMBO.... sorry, but that was funny when I first read it.

 

[Meta4]

Bud this ain't my first day!

That you suggested this drones "just flew away" and a likely cause was not recording a home point before launch suggests you still have a few things to learn

 

[Bigbird48]

My Mavic Air will notr even take off if theres any kind of magnetic interference. Is this not true with other mavic's?????

 

[msinger]

The aircraft is not always able to detect when the compass is being negatively affected by interference. That's why so many people manage to successfully take off before realizing things aren't working as expected.