Insane out of control crash

[AJButterfield]

Made three really short flights yesterday. I was on top of a parking structure. Just wanted to go straight up and down for a shot for a short film.

TLDR: Compass and IMUencountersheadingexception cause(?) Mavic to fly off and crash at full speed. How do I avoid this? Why did it happen? Is there a safe way to go up and down without risk of flying away like this?



Details:

1. I took off and the Mavic went up to 49m, hovering perfectly. The test footage was perfect so I wanted to go again, but with all the mess of equipment cleared up and the crew out of shot. Landed perfectly.

2. Needed compass calibration. I performed this (first time I ever had to, only owned it 3 days). Did this twice. Then when I took off, without me using the controller at all, it hovered at 4m, and then flew sideways, I managed to land it with a few seconds. According to flight record I had no GPS the whole flight.

3. I repositioned the drone in the position I wanted. When I took off I encountered a couple of warnings that stopped me. I turned everything off an started over. This time it took off and immediately started flying sideways at full speed, I received a compass error and 'working IMU encounters heading exception' error. As it left the parking structure it arced around the corner of the structure, losing altitude rapidly and crashed into a field, where it bounced back into the air and flew a little further before it either landed on its own, or because I was trying to land it. (I was using the down control and had hit the landing button in the app).

It was scary. It took off so fast with no control whatsoever.

 

[Mr. Salty]

My first thought is that you're not supposed to do a compass calibration standing on concrete or near metal, both of which a parking structure would have in abundance because of the steel support beams and rebar.

 

[flightmike]

Not knowing details about the structure you were on I would say you have a lot of interference there.
It gave you a compass and IMU warning because of interference.
Then you did the worst thing and calibrated with all that interference. Twice!
Please look up about calibrations. Always do in an open field with no metal around. The parking structure probably has a ton of rebar in the concrete.
Hopefully you didn't trash your MP.

 

[AJButterfield]

Thats a really piece of info to know.

Is there a simple way to limit flight to up and down?

 

[AJButterfield]

Not knowing details about the structure you were on I would say you have a lot of interference there.
It gave you a compass and IMU warning because of interference.
Then you did the worst thing and calibrated with all that interference. Twice!
Please look up about calibrations. Always do in an open field with no metal around. The parking structure probably has a ton of rebar in the concrete.
Hopefully you didn't trash your MP.

Thank you. I did calibrate on the structure. And will never do this again. Luckily no damage occurred. It could very easily have crashed into a building, road or tree. But got super lucky.

 

[AJButterfield]

It seems strange to me that it would take off at such a high speed because of something like this. What I'm after is just a slow steady movement that I control. Is there a way to prevent it from doing any of its own movements?

 

[flightmike]

No. There are limits in the app but not to go just up and down.
The compass's are what keep it steady.
I would really recommend reading the manual and watching some basic you tube videos before you fly again. May save you $1,000.
Not trying to sound harsh but there is a lot of technical settings and procedures to know to get the most out of your MP and to save you from loss or crash.
Had mine since April and only went into a tree once (pilot error). I read, watched and stayed on this forum for a couple weeks while waiting for my MP to learn everything I could.
This things amazing once you get to know it and can be great fun and less frustrating.
Read up and enjoy.

 

[AJButterfield]

No. There are limits in the app but not to go just up and down.
The compass's are what keep it steady.
I would really recommend reading the manual and watching some basic you tube videos before you fly again. May save you $1,000.
Not trying to sound harsh but there is a lot of technical settings and procedures to know to get the most out of your MP and to save you from loss or crash.
Had mine since April and only went into a tree once (pilot error). I read, watched and stayed on this forum for a couple weeks while waiting for my MP to learn everything I could.
This things amazing once you get to know it and can be great fun and less frustrating.
Read up and enjoy.

I didnt have that wait time. Bought it at a store, and its just so tempting to dive in and try it out. Also without encountering things its hard to know what to look up. I'll definitely be researching a lot more before taking it out again. I (incredibly naively) didnt anticipate such a violently out of control issue, especially after my first few flights were perfect.

Can you recommend any good beginner tutorial videos. There are so many out there and most are terrible, and not time efficient.


btw. Not 'harsh' at all. Much appreciated slap on the hand.

 

[StanTGM]

there is a channel called "51drones" on youtube. Very informative stuff there. Take your time taking it all in...

 

[Kilrah]

Is there a way to prevent it from doing any of its own movements?

These movements are not intended, the aircraft still tries to stay in place but since it has no more way of knowing what it's doing stuff becomes erratic. You obviously can't prevent that in any other way than not putting it in a situation where it can't keep its bearings.

 

[Rnl]

Don't forget to recalibrate compass in an open area before next flight..

 

[Blacksails]

On top of a parking structure? There's going to be absolutely tons of steel and iron support in that structure and you're standing directly on top of it. All drones that use a compass would have issue with this in gps / position hold mode.


The compass is used along with the GPS receivers to help the aircraft determine its position in 3D space. When you calibrate it, it takes a snapshot of the current magnetic field around it to use as a base for its readings. Calibrating in a field away from any structures allows the drone to take a clean snapshot of the earths magnetic field in that location. This changes all over the world, hence the need for recalibration if you travel far from the original calibration point, like to another country.


When you calibrated on top of that car park you gave the mavic a really bad snapshot, with tons of interference and noise created by the huge amount of metal in the parking structure. Not good. The moment the mavic starts moving, that field is changing drastically which will completely confuse the poor thing and cause it to freak out.
The same happens if flying indoors at some locations. With the mavic, it isn't a great idea.

With other DJI drones you can swap manually to Atti mode, which turns off gps and compass. If you could do that with the mavic then you could safely fly indoors or in areas of high magnetic interference, like on top of that structure. The only difference is that Atti mode doesn't try to hold the crafts position and so it has to be piloted manually. Difficult if you haven't flown before.

I'll never quite understand why DJI didn't include Atti mode on the mavic. It's a small drone, perfectly sized for indoor flight, but can't be trusted indoors as you can't activate Atti mode manually.

Really old DJI drones used to have full manual mode too, which was like flying the old gas helicopters. That was wonderful. I managed to flip our old, retired heavy lift octocopter once in that mode. Lots of fun!

Just a little side note and probably what happened to your mavic -The dreaded toilet bowl effect. Normally caused by magnetic interference - causes the drone to start spiralling uncontrollably, gaining speed, like it is being flushed down a gigantic toilet.

I recently got back from filming with an Inspire in Iceland. There's tons of magnetic interference over there due to the high metal content in the volcanic rock that makes up huge parts of the island. I witnessed somebody flying a phantom 4 over Godafoss waterfall. It started toilet bowling aggressively and plunged into the river. Magnetic interference. I popped the Inspire up in attitude mode an all was fine, except for having to battle the wind. I flicked into GPS very briefly to double check and the moment I did she started the slow spiral into a full on toilet bowl effect, then stopped immediately when switched again. Things like this are handy to know and can save your *** from a silly and expensive mistake. Really read up on stuff. Unfortunately with the mavic we just have to avoid these situations entirely.

Entirely too long of a reply with unnecessary information, I realise... but it's late and I can't sleep

 

[StanTGM]

Entirely too long of a reply with unnecessary information, I realise... but it's late and I can't sleep

fun to read anyways

 

[AJButterfield]

On top of a parking structure? There's going to be absolutely tons of steel and iron support in that structure and you're standing directly on top of it. All drones that use a compass would have issue with this in gps / position hold mode.


The compass is used along with the GPS receivers to help the aircraft determine its position in 3D space. When you calibrate it, it takes a snapshot of the current magnetic field around it to use as a base for its readings. Calibrating in a field away from any structures allows the drone to take a clean snapshot of the earths magnetic field in that location. This changes all over the world, hence the need for recalibration if you travel far from the original calibration point, like to another country.


When you calibrated on top of that car park you gave the mavic a really bad snapshot, with tons of interference and noise created by the huge amount of metal in the parking structure. Not good. The moment the mavic starts moving, that field is changing drastically which will completely confuse the poor thing and cause it to freak out.
The same happens if flying indoors at some locations. With the mavic, it isn't a great idea.

With other DJI drones you can swap manually to Atti mode, which turns off gps and compass. If you could do that with the mavic then you could safely fly indoors or in areas of high magnetic interference, like on top of that structure. The only difference is that Atti mode doesn't try to hold the crafts position and so it has to be piloted manually. Difficult if you haven't flown before.

I'll never quite understand why DJI didn't include Atti mode on the mavic. It's a small drone, perfectly sized for indoor flight, but can't be trusted indoors as you can't activate Atti mode manually.

Really old DJI drones used to have full manual mode too, which was like flying the old gas helicopters. That was wonderful. I managed to flip our old, retired heavy lift octocopter once in that mode. Lots of fun!

Just a little side note and probably what happened to your mavic -The dreaded toilet bowl effect. Normally caused by magnetic interference - causes the drone to start spiralling uncontrollably, gaining speed, like it is being flushed down a gigantic toilet.

I recently got back from filming with an Inspire in Iceland. There's tons of magnetic interference over there due to the high metal content in the volcanic rock that makes up huge parts of the island. I witnessed somebody flying a phantom 4 over Godafoss waterfall. It started toilet bowling aggressively and plunged into the river. Magnetic interference. I popped the Inspire up in attitude mode an all was fine, except for having to battle the wind. I flicked into GPS very briefly to double check and the moment I did she started the slow spiral into a full on toilet bowl effect, then stopped immediately when switched again. Things like this are handy to know and can save your *** from a silly and expensive mistake. Really read up on stuff. Unfortunately with the mavic we just have to avoid these situations entirely.

Entirely too long of a reply with unnecessary information, I realise... but it's late and I can't sleep

Not at all. I appreciate the lessons. I've noticed that the Mavic enters ATTI mode on a regular basis (when starting up for example, and other times that I started the motors inside and stuff). Is it for sure not possible to do this manually. Seems like that could be a good way to use it if I ever get caught out again.

 

[Robbyg]

The first thing I think you did wrong was the compass calibration in an area like that. You should calibrate the compass out in an open field, no buildings or metal nearby.
Once calibrated you should not need to do it again unless you travel a thousand miles or more from the original calibration location or you do a firmware update. Also Ignore warnings that it needs calibration if your trying to take off in an area that has buildings, electronics or metal nearby. You will be calibrating it to an incorrect magnetic field and that can cause the results you had.

The second problem I see is that it seems like your taking off before the IMU has warmed up and the GPS has had time to lock onto the needed satellites. On power up the Mavic is in ATTI mode, it needs about 45 seconds to get into GPS mode and warm up its systems. Look at the screen and make sure it has at least 9 satellites locked and is in GPS mode before you lift off.

The other question is did you wait until it said "The Home Point is recorded, check it on the map" If not the Mavic had no home position. Also for precise landing after the position has been recorded you need to slowly climb up to about 33 ft and let the bottom cameras take photos of the landing area.

Rob

 

[Blacksails]

Not at all. I appreciate the lessons. I've noticed that the Mavic enters ATTI mode on a regular basis (when starting up for example, and other times that I started the motors inside and stuff). Is it for sure not possible to do this manually. Seems like that could be a good way to use it if I ever get caught out again.

Happy to help.

Definitely not possible. On the mavic you have a selection between sport and GPS mode, both of which use the compass.

On drones like the phantom/Inspire/etc you have a 3 position switch with attitude mode in the middle.

There is a way (through hacking) of swapping the sports mode switch to go between gps mode and Atti mode, but I wouldn't recommend that. I tried it and although Atti became switchable, it still seemed to be attempting use compass data, as it behaved erratically indoors, exactly as it does in gps mode with interference.

 

[Gerry65]

Good and informative responses from the crew here. I know when I try to calibrate and I'm too close to my car, or any vehicles, I get a calibration error. I have to move at least 20 or so yards away. Surprised there wasn't a calibration error given before the your attempt to take off. Or, maybe there was but you didn't notice it when calibrating.

 

[ml92760]

I had a very strange issue happen today with a Mavic pro about 4 weeks old . I have flown it at my home may times very country area upon ( auto take ) off the aircraft climbed past 4 feet and when I put the rotor power down it said landing. I canceled the landing and tried hover the aircraft kept climbing( slowly which i though odd with no stick control. I then put the power down and it landed I landed the aircraft and then I got the "compass redundancies switch error" Never seen this before?
. Immediately powered the aircraft down also powered down the remote control. Remove the battery. Reinstall the battery powered on both the aircraft and remote control. At this point I forced calibration it was successful, no errors However before take off I was still getting the compass redundancy switch error? I powered off the aircraft and looked online for info on this error, the only thing I could find was to check the difference between compass #1 and #2 ( they should be close under sensors) I went back outside and started the Mavic I then began to received the compass redundancy error. I re-calibrated the aircraft successfully. I then went to sensors and looked at the difference between compass number one encompass number two they were within three or four points of each other. I then did an auto takeoff in the aircraft continued ascending again past 4 feet very slowly, then the aircraft despite downward on left stick it kept climbing at about 200 feet it ascended very quickly ( full stick down ) no reply I figured at 380 - 400 it will stop, not a chance ( said Max altitude reach but she kept going !!) The Maviic report an altitude of 680 feet I hit return home, and still no reply and then at about just under 700 feet it started to down and said " return home " the problem was it was dropping very very fast . I attempted to assure it was over my property then all power cut and the thing went into free fall I did manage to restart the props at about 50' but it again gut out an slammed on my drive way... I must say the Carbon fiber guard I installed took the brunt of the impact but it still trashed the drone ..Its an odd feeling to not have control ,, I fly professionally and have had it happen on the Swell Pro Splash drone, we call it the "Crash drone," very bad flight controller!! as well as another UAV and it is not a good feeling. This is the first time with any of my DJI products, other than when we filled the sinking of a ship 26 miles off shore .. we lost a Phantom 3 advanced to some odd flight interference.... So being a new UAV makes it even more troubling... so the Firmware was up to date on the craft and controller as well as the I-pad... I am sending it back to DJI for evaluation and repair... the odd thing is the one I had before this out of the box would go into Auto landing mode non stoop landing Mode 9 out of 10 flights and not allow me to cancel the landing so we could not fly it ... We love the Mavic when she is running smooth but I am beside myself with 2 bad drone in a row.... just wanted to share this with you all in the event you had any like issues... with Compass error... be carefull of the dreaded fly-away..

 

[kidroc]

that carbon thing you installed caused all of your pain they mess with the senors very badly never put anything under there unless DJI makes it..

 

[ml92760]

Really that is odd as the night before I also flew it with CF guard and without issue ...I have never heard of this on any threads. Thanks for the input for sure ...