Compass error forces ATTI mode, even though I had 12-16 satellites

[noooris]

I went flying next to my building today and a compass error forced ATTI mode. Luckily my spark wasn’t far or high so I spotted her in time before she slammed into my building. I’m surprised at how fast it drifted off considering it wasn’t windy at all. I’m also confused as to why it forced ATTI mode when it had a minimum of 12 satellites locked throughout the flight. It should remain in GPS mode and hover in place, even if it doesn’t know North from South.

Here’s the video:

 

[smith]

I went flying next to my building today and a compass error forced ATTI mode. Luckily my spark wasn’t far or high so I spotted her in time before she slammed into my building. I’m surprised at how fast it drifted off considering it wasn’t windy at all. I’m also confused as to why it forced ATTI mode when it had a minimum of 12 satellites locked throughout the flight. It should remain in GPS mode and hover in place, even if it doesn’t know North from South.

Here’s the video:

How did you manage to controll it?

 

[The Editor]

I went flying next to my building today and a compass error forced ATTI mode. Luckily my spark wasn’t far or high so I spotted her in time before she slammed into my building. I’m surprised at how fast it drifted off considering it wasn’t windy at all. I’m also confused as to why it forced ATTI mode when it had a minimum of 12 satellites locked throughout the flight. It should remain in GPS mode and hover in place, even if it doesn’t know North from South.

Here’s the video:

The number of satellites locked or received is pretty meaningless and people get hung up on the idea of "well I had 47 satellites on my display so it shouldn't have lost GPS"
This is wrong, the important thing is Horizontal and Vertical dilution of precision or HDOP/VDOP for short and this is shown as the small bar graph display next to the satellite numbers.
Since you will only really see maximum of 12 satellites above the horizon in any one constellation at any time seeing 7 or 8 sats could mean 3 from NAVSTAR (GPS) and 4 from Glonass constellations so your positional accuracy can not only be hindered by dilution of precision but also triangulation accuracy of the numbers of sats received from one constellation.

 

[noooris]

The number of satellites locked or received is pretty meaningless and people get hung up on the idea of "well I had 47 satellites on my display so it shouldn't have lost GPS"
This is wrong, the important thing is Horizontal and Vertical dilution of precision or HDOP/VDOP for short and this is shown as the small bar graph display next to the satellite numbers.
Since you will only really see maximum of 12 satellites above the horizon in any one constellation at any time seeing 7 or 8 sats could mean 3 from NAVSTAR (GPS) and 4 from Glonass constellations so your positional accuracy can not only be hindered by dilution of precision but also triangulation accuracy of the numbers of sats received from one constellation.

The last moment in GPS mode before it flipped to ATTI mode, exclusively due to a compass error and not anything to do with GPS signal, quality, dilution, or triangulation.

 

[noooris]

How did you manage to controll it?

I got lucky, I’m not an expert pilot by any means.

 

[The Editor]

The last moment in GPS mode before it flipped to ATTI mode, exclusively due to a compass error and not anything to do with GPS signal, quality, dilution, or triangulation.

Correct - compass error will cause the aircraft to switch to Atti mode.
That is the correct behavior as it is programmed to do.

 

[noooris]

Correct - compass error will cause the aircraft to switch to Atti mode.
That is the correct behavior as it is programmed to do.

I get that this is what its programmed to do, but its definitely a bug, not a feature. It has everything it needs to hover in place. It should not force switch to ATTI, and then drift with the wind, risk a collision with the building, and risk drifting out of range.

 

[The Editor]

I get that this is what its programmed to do, but its definitely a bug, not a feature. It has everything it needs to hover in place. It should not force switch to ATTI, and then drift with the wind, risk a collision with the building, and risk drifting out of range.

Yes it should.
Do some research as to why Atti is forced in the event of compass error.
If Atti wasn't forced at the point of error the aircraft would suffer TBE (toilet bowl effect) since the compass data would be at odds with the GPS data.
This is a well known phenomenon. Most pilots could not cope with controlling an aircraft that has gone into TBE since stick inputs do not correlate to aircraft attitude. Atti is the best option to give the operator control back.
In fact, your flight path shows classic signs of the beginnings of TBE so you were fortunate the aircraft went into Atti. If it hadn't I fear it would not have ended well for you.
Atti mode does not 'cause' crashes, only poor piloting when in Atti will result in a crash

 

[noooris]

Thanks for this info. I’m happy I controlled it and it didn’t crash or flyaway. I really want to learn to be a better pilot in ATTI mode.

 

[webvan]

Yep and too bad that mode can't be forced on the Spark to practice!

 

[Mako79]

@noooris
Did you do a compass dance before flight next to your car or near metal structures?

 

[noooris]

I hadn't calibrated the compass for over week. I think the problem is that I powered on and took off sandwiched between my metal car and that big corrugated sheet metal parking structure.

 

[noooris]

I would like to add that I now discovered, much like the other threads that I not only got a compass error, but a NFZ error (no where near NFZ), and a IMU error. Basically every smart system failed and it was just a flying fan.

 

[mlash]

I went flying next to my building today and a compass error forced ATTI mode. Luckily my spark wasn’t far or high so I spotted her in time before she slammed into my building. I’m surprised at how fast it drifted off considering it wasn’t windy at all. I’m also confused as to why it forced ATTI mode when it had a minimum of 12 satellites locked throughout the flight. It should remain in GPS mode and hover in place, even if it doesn’t know North from South.

Here’s the video:

That was a great recovery. You done just what you should have done! Stay calm, assess the situation and bring it back safely. Now you have experience and know that you will do what your supposed to do when it gets critical!

 

[Rick Morton]

Let me chime in! I bought my Spark specifically to take to the Maine coast on our road trip. A week after I got it, it took off in ATTI mode while flying only about 50 feet from me in the middle of nowhere. Luckily, I got GPS back and brought it home. I've been scared to death flying ever since. I got some nice footage in a few cemeteries this week, although nothing really high or far out. Then we went to a small inlet to get some shots. There was NOTHING around. This little village doesn't even have a traffic light. No wires, no buildings where I was. I took off and in about 15 seconds got a "Warning... interference. Turn off wifi or bluetooth devices..." Something like that. I immediately came down and turned off cell phone and Apple Watch. The App was all green, 12 satellites, and I took off. Went up about 30 feet and out about 50. Was turning at the Spark went into ATTI mode and took off at much faster speed than I was going, which was really slowly since I was scared to fly as it was. I'm not an experiences ATTI pilot, to say the least, and I couldn't control it. It hit the trees and crashed to the ground. Luckily not into the water. Physically it looks fine but turning it on gives me all kinds of error messages. I'll be sending it in.
I agree with Noooris... and I just don't understand... why DJI can't fix this issue. The drone is MADE to work based on GPS positioning. Why do they let it just "LOSE" GPS all of a sudden... then take off like a bat out of hell. Why not at least TRY to make it hover so those of us who aren't experts can at least try to gain some control? I don't get it. And why does it increase speed, making things even worse?
I didn't do a compass calibrate, I'll admit that, but why, if that were the problem, did it wait to get 50 ft. away before it crapped out? Why not let me know before I take off?
I'm so frustrated with this. A lot of money and I'm scared to fly the thing because it can choose to drop signal and fly away any time. A real bummer.

 

[Lastrexking]

What happens if you press the pause button whilst in ATTI?

 

[Dronason]

Let me chime in! I bought my Spark specifically to take to the Maine coast on our road trip. A week after I got it, it took off in ATTI mode while flying only about 50 feet from me in the middle of nowhere. Luckily, I got GPS back and brought it home. I've been scared to death flying ever since. I got some nice footage in a few cemeteries this week, although nothing really high or far out. Then we went to a small inlet to get some shots. There was NOTHING around. This little village doesn't even have a traffic light. No wires, no buildings where I was. I took off and in about 15 seconds got a "Warning... interference. Turn off wifi or bluetooth devices..." Something like that. I immediately came down and turned off cell phone and Apple Watch. The App was all green, 12 satellites, and I took off. Went up about 30 feet and out about 50. Was turning at the Spark went into ATTI mode and took off at much faster speed than I was going, which was really slowly since I was scared to fly as it was. I'm not an experiences ATTI pilot, to say the least, and I couldn't control it. It hit the trees and crashed to the ground. Luckily not into the water. Physically it looks fine but turning it on gives me all kinds of error messages. I'll be sending it in.
I agree with Noooris... and I just don't understand... why DJI can't fix this issue. The drone is MADE to work based on GPS positioning. Why do they let it just "LOSE" GPS all of a sudden... then take off like a bat out of hell. Why not at least TRY to make it hover so those of us who aren't experts can at least try to gain some control? I don't get it. And why does it increase speed, making things even worse?
I didn't do a compass calibrate, I'll admit that, but why, if that were the problem, did it wait to get 50 ft. away before it crapped out? Why not let me know before I take off?
I'm so frustrated with this. A lot of money and I'm scared to fly the thing because it can choose to drop signal and fly away any time. A real bummer.

The compass error can come from a divergence of the direction given by the compass the direction calculated by the flight controller (yaw value). This typically happen mid flight and not at take off. If the compass is totally wrong, then the Spark with not even turn-on. Here we are more in the grey zone between good and bad.

If you want to know real reasons you need to retrieve the DAT file (flight record stored in the Spark) as explained HERE. You can upload it to something like dropbox and post a link here.
Then it can be checked more in details. There is limited space for these flight records in the Spark, older are deleted to have space for new ones, so retrieval should be done as early as possible.
You can also do it yourself from the DAT file and plot flight parameters using the CsvView tools available HERE.

 

[Rick Morton]

The compass error can come from a divergence of the direction given by the compass the direction calculated by the flight controller (yaw value). This typically happen mid flight and not at take off. If the compass is totally wrong, then the Spark with not even turn-on. Here we are more in the grey zone between good and bad.

If you want to know real reasons you need to retrieve the DAT file (flight record stored in the Spark) as explained HERE. You can upload it to something like dropbox and post a link here.
Then it can be checked more in details. There is limited space for these flight records in the Spark, older are deleted to have space for new ones, so retrieval should be done as early as possible.
You can also do it yourself from the DAT file and plot flight parameters using the CsvView tools available HERE.

The compass error can come from a divergence of the direction given by the compass the direction calculated by the flight controller (yaw value). This typically happen mid flight and not at take off. If the compass is totally wrong, then the Spark with not even turn-on. Here we are more in the grey zone between good and bad.

If you want to know real reasons you need to retrieve the DAT file (flight record stored in the Spark) as explained HERE. You can upload it to something like dropbox and post a link here.
Then it can be checked more in details. There is limited space for these flight records in the Spark, older are deleted to have space for new ones, so retrieval should be done as early as possible.
You can also do it yourself from the DAT file and plot flight parameters using the CsvView tools available HERE.

Thanks. I spoke with DJI tech support and they sent me a label to send the Spark in for repair. I get all kinds of red errors when I turn it on so it definitely needs repair one way or the other. The guy said it might be a Spark problem, but they'll look at the flight records to determine. Either way, I've got the Refresh so I'm good. Just wish I could somehow guarantee this wouldn't happen so i won't be afraid to fly.

 

[andy_drew]

Q: What happens if you press the pause button whilst in ATTI
A: In atti mode neither pause button nor RTH will work.

Q: Why do they let it just "LOSE" GPS all of a sudden... then take off like a bat out of hell. Why not at least TRY to make it hover so those of us who aren't experts can at least try to gain some control? I don't get it. And why does it increase speed, making things even worse?
A: When GPS is lost and the drone goes into atti mode, the drone is able to maintain its altitude but unable to maintain is position (GPS is needed to keep the drone in one place) and will therefore drift with even the slightest breeze. This is why people assume the drone has 'flown away' by it's own accord but in actual fact it has just 'gone with the wind'. As the drone has no ability to break it is at the mercy of the wind and just gets faster and faster as it gathers pace. This is why it is never a good idea to fly on a windy day as if you go into atti mode for any period of time you can kiss goodbye to your drone. If ever you find yourself in atti mode, whack you RC into sport mode to give you a fighting chance of combating the any wind and get it back to an area where you can safely ground the aircraft and retrieve it.