Was out Saturday afternoon flying my new Spark getting some cool footage of graffiti under a train bridge but things ended very badly.

* Started the flight with good GPS and home position. Took off and did a 'dronie' of the bridge without incident. Drone was behaving fine for all of this.

* Lined the drone up north of the bridge and started to slowly pan across some cool graffiti. Drone was still behaving as expected.

* As I flew under the bridge (about 100' away from my position, maybe 50' off the ground, 20' under the bridge deck) I received this warning: "Warning In Flight, working compass encounters magnetic-field interference please switch to ATTI mode if craft behave abnormally"

* At that point I lost control of the drone - it did a little hitch, then took of in a long parabolic arc which ended with a crash into a tree and dropping into the river.

* Reviewing the flight long it really looks like it lost compass as it passed under the bridge but then quickly stopped responding to control inputs.

I have flight logs but I'm not sure how to export them and attach them here but it looks to me like as soon as the drone passes under the bridge it loses compass. At that point it throws up the ATTI warning and takes off. If I did something wrong I'd love to know what it was - perhaps I should have been flying in ATTI mode all along or something?

I really don't think that this was my fault - drone was within LOS, good connection, fully charged, flown safely - I just can't figure out what I might have done differently.

Can anyone here give me any advice on how to approach this with DJI - If I'm responsible I'd like to know what I did wrong. If I'm not I'm hoping for some warranty support on my 2 month old drone.

Bridges are full of concrete and metal which will interfere with the WiFi connection that the Spark uses to communicate. It's possible this is the reason for the disconnect.

sorry for the incident.
you can take the logs out of the phone (connect the phone to the computer and look for the DJI folder. you will find the logs). then upload them here: http://www.phantomhelp.com/LogViewer/Upload/
i would say the main issue here was the bridge. metal, steel, concrete affected the compass of your drone. but the logs may show something different

After reading the a lot of crash posts on this forum, it seems that one common thread is flying near structures or power lines. The metal bridge probably interfered with the compass and possibly caused the GPS to loose connection.

A couple of comments based on feedback thus far:

I can understand how the bridge would interfere with compass & GPS, but it seems unlikely that I lost connection with it from the remote because I have telemetry information for the drone right up until impact.

Assuming that to be the case, wouldn't the expected behavior be for the drone to drop into ATTI mode and require me to manually fly it back home? I completely understand how a structure could block GPS etc, but I don't understand why this would cause it to fly away on its own - especially if I still had a connection with it as demonstrated by the flight log.

JoeCec Posted at 2018-2-20 06:04
Bridges are full of concrete and metal which will interfere with the WiFi connection that the Spark uses to communicate. It's possible this is the reason for the disconnect.

Is this accurate? I thought magnetic interference only affected the compass, and fly aways were mostly due to pilots not being used to flying in atti?

This statement (and I've read cases of such, but thought they were rare) is saying if a pilot starts getting compass interference, they should also be prepared to have zero control over the aircraft. Am I reading this correctly?

Spark is especially sensitive to metals: even the metal in landing pads trigger the "calibrate compass". Try not to try fly it anywhere near any metal structure.

Remember: NEVER EVER FLY IT UNDER A BRIDGE

Marc Davis Posted at 2018-2-20 06:35
A couple of comments based on feedback thus far:

I can understand how the bridge would interfere with compass & GPS, but it seems unlikely that I lost connection with it from the remote because I have telemetry information for the drone right up until impact.

It would drop into ATTI mode and require you to manually fly it back home.  How many months have you been flying drone in ATTI (Attitude mode) and in RATE mode?  It takes great skills to fly an unstabilized RC drone.  Most drone pilots can't fly a drone and rely on autopilot to keep the flight under control.

Attitude mode will limit how tilted the drone can get and will bring it to roughly horizontal when sticks are released.  It will not stop the drone racing in one direction or another.  The pilot would have to input opposite thrust to stop the drone once it is moving.  And it will constantly try to fly off because its horizontal isn't perfect and it is slow to return to that horizontal position.  Rate mode allows you to fully flip the drone inverted, fly in any tilt you want, and stay in that tilt or invert until you give opposite stick.  Sadly, the Spark doesn't have Rate mode.

Beginners in ATTI mode gives you a drone acting like it is drunk as the nut on the control sticks over compensates, gives wrong inputs, gets disorientated, and panics.  I bet Hallmark's drone that the flight record shows the stick inputs match the actions of the drone as it accelerated away.   Matched the stick inputs even if the drone didn't stop and hover like the owner expects when he centered the sticks.

Gunship9 Posted at 2018-2-20 10:00
It would drop into ATTI mode and require you to manually fly it back home.  How many months have you been flying drone in ATTI (Attitude mode) and in RATE mode?  It takes great skills to fly an unstabilized RC drone.  Most drone pilots can't fly a drone and rely on autopilot to keep the flight under control.

Attitude mode will limit how tilted the drone can get and will bring it to roughly horizontal when sticks are released.  It will not stop the drone racing in one direction or another.  The pilot would have to input opposite thrust to stop the drone once it is moving.  And it will constantly try to fly off because its horizontal isn't perfect and it is slow to return to that horizontal position.  Rate mode allows you to fully flip the drone inverted, fly in any tilt you want, and stay in that tilt or invert until you give opposite stick.  Sadly, the Spark doesn't have Rate mode.

You may be right - but when I replay the flight within the app the drone takes a very smooth course out across the river in a gentle but fast parabola. Stick inputs, however, are what you describe - over-compensation in an attempt to regain control. The drone's path is smooth, the control sticks are all over the place.

In the past flying in ATTI mode - as recommend here for practice - I've found it to be extremely sensitive to control inputs and would expect, based on the log, a janky course to disaster. You may be right, but it doesn't look that way to me.

please dji sort a bloody function out so we can select flight modes.
we've seen through the go 4 app mod what the spark can do, but dji have chosen to turn features off even though they work.
its bad enough that the claims in advertising of gesture control / selfie drown are so far from the truth as well as the poor range, rc or not in any eu country.
i plea, manual  flight select please.

Marc Davis Posted at 2018-2-20 10:58
You may be right - but when I replay the flight within the app the drone takes a very smooth course out across the river in a gentle but fast parabola. Stick inputs, however, are what you describe - over-compensation in an attempt to regain control. The drone's path is smooth, the control sticks are all over the place.

In the past flying in ATTI mode - as recommend here for practice - I've found it to be extremely sensitive to control inputs and would expect, based on the log, a janky course to disaster. You may be right, but it doesn't look that way to me.

Then I may owe you Hallmark's drone.  I would never bet my own drone but his drone, or anyone else's drone, I feel more free to waste.

I would have expected the sticks to cause the drone's roll data, pitch data, or yaw data to move wildly as it followed the controller.  However, its path could be sorta constant but the changing attitude of the drone would have to impact the path.  Yes, a janky course somewhat depending on how long the opposite tilt is input and how much momentum the course already has.  

I wonder if the drone is chasing failed GPS data in that parabola before it decides things are wrong, so it drops into ATTI mode when it is already racing off course.  Autopilot saying, "I'm crashing!  Here, you take the controls."  Then the Autopilot taking a few secondes to give you the controls.

Marc Davis Posted at 2018-2-20 10:58
You may be right - but when I replay the flight within the app the drone takes a very smooth course out across the river in a gentle but fast parabola. Stick inputs, however, are what you describe - over-compensation in an attempt to regain control. The drone's path is smooth, the control sticks are all over the place.

In the past flying in ATTI mode - as recommend here for practice - I've found it to be extremely sensitive to control inputs and would expect, based on the log, a janky course to disaster. You may be right, but it doesn't look that way to me.

Marc, sorry to hear of your loss.  I would suggest uploading your logs to the following site (instructions on the upload page) and pasting the link to the resulting page here.

http://www.phantomhelp.com/LogViewer/Upload/

Quite a lot can be learned by looking at the details.  I'd certainly be interested in learning from your experience.

fansa6d9d300 Posted at 2018-2-20 12:22
please dji sort a bloody function out so we can select flight modes.
we've seen through the go 4 app mod what the spark can do, but dji have chosen to turn features off even though they work.
its bad enough that the claims in advertising of gesture control / selfie drown are so far from the truth as well as the poor range, rc or not in any eu country.

All dji drones act the same way when loosing gps whether through compass problem or just gps being blocked, a switch will make no difference.
Inspire 2 P4Pro both of these Aircraft have an Atti switch, but when there is a problem with compass gps etc they do exactly the same as spark Mavic and now MavAir. They go automatically into Atti mode and this is a built in failsafe to allow user to still have aircraft in P mode (gps mode) so if gps returns compass corrects itself then gps will be automatic.
If you had to switch to Atti mode how would you know if compass corrected itself and gps returned unless you keep flicking back and forth while trying to control aircraft in Atti mode.

The only reason for having Atti switch on aircraft is operator can practice or fly in Atti mode by choice. It won’t make one bit of difference when you lose gps or have compass problems.

Gunship9 Posted at 2018-2-20 10:00
It would drop into ATTI mode and require you to manually fly it back home.  How many months have you been flying drone in ATTI (Attitude mode) and in RATE mode?  It takes great skills to fly an unstabilized RC drone.  Most drone pilots can't fly a drone and rely on autopilot to keep the flight under control.

Attitude mode will limit how tilted the drone can get and will bring it to roughly horizontal when sticks are released.  It will not stop the drone racing in one direction or another.  The pilot would have to input opposite thrust to stop the drone once it is moving.  And it will constantly try to fly off because its horizontal isn't perfect and it is slow to return to that horizontal position.  Rate mode allows you to fully flip the drone inverted, fly in any tilt you want, and stay in that tilt or invert until you give opposite stick.  Sadly, the Spark doesn't have Rate mode.

I have 6 drones, which one you auctioning off ?
You will find you will almost certainly be correct and I will still have all my drones, Atti mode becomes very difficult in tight spaces and it’s easy to get disoriented, it is a lot easier if your in full VLOS and your drone is 20 metres in the air with no obstacles including wind, include obstacles wind and tight quarters and Houdini would have great difficulty escaping this situation.

Check out UAVFlyaways.com

It's a new site keeping track of fly away issues.

That's interesting, I think there have been several other Spark owners who lost their aircraft in a similar manner. If you wanna have a look at my opening post here (https://forum.dji.com/forum.php? ... p;page=1#pid1212151), you'll see that I almost lost mine as well. Fortunately, in my case, the Spark was in a much more favorable (=open) environment and I managed to land it safely, but there was a moment when I didn't really have control over it, despite having a very good connection. It was as if it had a mind of its own, and went off in a random direction at full speed, unless I applied full throttle in the other direction (I've been piloting quads and RC-helicopters for over 10 years, which helped me keep my cool). Eventually it stopped doing doing that and I immediately brought it down, that's when it gave a me GPS error and compass error.

I'll never know with certainty what had happened that day, but I got advised that I had to calibrate the IMU more often, and stay away from large metal structures, and it hasn't happened since. But I do know that the Spark can do some weird stuff in the air, that was not just normal ATTI mode behaviour.

hallmark007 Posted at 2018-2-20 15:08
I have 6 drones, which one you auctioning off ?
You will find you will almost certainly be correct and I will still have all my drones, Atti mode becomes very difficult in tight spaces and it’s easy to get disoriented, it is a lot easier if your in full VLOS and your drone is 20 metres in the air with no obstacles including wind, include obstacles wind and tight quarters and Houdini would have great difficulty escaping this situation.

"I have 6 drones, which one you auctioning off ?"  

I am not sure I could accurately fly the Spark in ATTI on my first effort.  My plan is to arrest its escape and try for a soft crash landing near me or where I can find it.  It is why I don't fly over or near, water.

I have flown unstabilized RC helicopters but you had to slowly acquire a feel for how much stick input did what.  It made my first Spark flight initially rough as I kept adding reverse thrust and throttle to stop its forward momentum.  It was too much since the Spark would self brake its forward motion when the stick was centered.

I find it interesting that the OP Spark did a smooth parabola while the owner worked the sticks.  Momentum keeping it going when the pilot didn't give it enough, or long enough, reverse thrust or throttle?

hallmark007 Posted at 2018-2-20 14:56
All dji drones act the same way when loosing gps whether through compass problem or just gps being blocked, a switch will make no difference.
Inspire 2 P4Pro both of these Aircraft have an Atti switch, but when there is a problem with compass gps etc they do exactly the same as spark Mavic and now MavAir. They go automatically into Atti mode and this is a built in failsafe to allow user to still have aircraft in P mode (gps mode) so if gps returns compass corrects itself then gps will be automatic.
If you had to switch to Atti mode how would you know if compass corrected itself and gps returned unless you keep flicking back and forth while trying to control aircraft in Atti mode.

then we need to be able to turn both off then, simple.

fansa6d9d300 Posted at 2018-2-21 01:13
then we need to be able to turn both off then, simple.

Doesn’t make sense turn both what off?

People just need to realize what they are doing .

i for one would like to make shots going throw lake tunnels, bridges ect. if we could turn off the gps, downward vison senors and switching to atti from launch we would have full control from start with at least a hope of getting out the other side.
by what i've seen there seems to be some sort of time laps were the spark is confused before responding to controls when the gps is lost, for some by then its to late.
try flying indoors in poor to no lighting and see what happens then, its mainly using the vision sensors for positioning.

El Diablo Posted at 2018-2-21 06:38
This whole ATI - fly way issue is plain stupid and people should stop justifying it. When I flew indoors, there was 0 GPS signal and the Spark obviously was in ATI mode (at least it was written on the screen). The drone never 'flew' away out of a window on its own and every time I released the sticks it just hoovered (very accurately I must admit) in place. Why DJI is not programming the thing to stay in place when connexion is lost I do not understand, or auto RTH... why the drone engage in these weird fly paths is a mistery...

The Spark is advertized as an entry level, family drone for God sake! IMO very few of the owners have experience flying in ATI mode under bridges, it is not written anywhere in the manual that when and if the drone loses conexion it will keep it's previous direction or fly away. Period.

El Diablo,

Your situation inside is much different than outside.  Firstly, inside there is no wind.  The wind plays a HUGE factor when the aircraft is in ATTI mode.  Also, when you were inside, I would guess that the downward visual sensors (VPS) were very likely engaged and able to assist with locating it.  Outside in most flying conditions, the aircraft will very likely be too high (DJI documents up to 8 meters) for the visual positioning system to function.  

Once you throw in the wind and take away the VPS system, it is a whole different situation when in ATTI mode.  If you've ever flown another quad-copter that does NOT have GPS position hold functionality in even a light breeze, you will understand.

The problem for the Spark has really been compass/yaw errors.  When those happen, it dumps out of GPS mode into ATTI mode because it doesn't know what to trust in terms of its heading.  The Mavic Air has implemented a new "Vision Compass".  This quote is from the their marketing materials:


"The Vision Compass will assist the navigation system to estimate flight direction when the compass experiences interference. When only one direction of the front, bottom, or rear vision systems is functioning normally, the aircraft will still position itself "


This obviously doesn't help the Spark that doesn't have this new technology, but its obviously something DJI is looking to resolve with future drones.


The best recommendation I have for Spark flyers is to make sure to get a good compass calibration, then leave it alone and make sure to stay away from objects and locations that would interfere with the compass.  I think too many people are doing too many calibrations in locations that aren't great or near objects that affect the compass.  


-KlooGee

The vision system seems to put paid to the much vaunted 'dual compass' on other drones.
I don't fly much, but have never experienced any of these 'errors' .
Only today someone complained of 'navigation' errors, and electra asked if they'd crashed, and it had fallen off the table.
At least they were honest.
Why ask why DJI don't program it to stay put when gps is lost? How do you think it stays put?

Oh well, there we go.

Marc Davis Posted at 2018-2-20 06:35
A couple of comments based on feedback thus far:

I can understand how the bridge would interfere with compass & GPS, but it seems unlikely that I lost connection with it from the remote because I have telemetry information for the drone right up until impact.

Marc, sorry for you loss. In you situation, please contact our support and start a case: http://www.dji.com/support You can provide them the flight records for further check and locate the problem. Thanks for your support.