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Mavic Pro 1 takeoff (flyaway) crash

DroneFilmmaker

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I was taking the MP for a second flight to film the snowfall this morning and had a crash at takeoff. I was hand launching it about 10 feet from our house (which I do all the time) and as I started the props and let go of the drone it took off quite fast to the side and crashed into the side of the house. It hit hard enough to make a couple holes in the vinyl siding and even made a small hole in the aluminum downspout. Folded both of the front arms back against the body and shredded 3 of the props.

It looked like everything else was good, but on a more thorough inspection it seems like it messed up the gimbal. Visually it looks fine, but on the phone it shows a gimbal overload error and there is no video feed. It also doesn't go through the "gimbal dance" on startup.

So my questions are:
#1 What would have caused it to fly into the side of the house on its own? It wasn't wind since there wasn't much wind and it definitely was not moving that fast. It wasn't accidentally moving the sticks because I only had my hand on the left stick and the other one was holding the drone. I can't imagine it was compass interference because I've taken off from this spot dozens of times with no issues, and I had actually flown from there about an hour earlier. The only thing I can think of is that it was in VISION mode (hadn't gotten GPS yet) but I take off in Vision mode all the time without any problems. Could the snow have been messing something up?

#2 What is going on with the gimbal? Is it the ribbon cable or possibly something else?

Thanks everyone!
 

old man mavic

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@DroneFilmmaker you should not have taken off in vision mode ,you should always make sure you have a GPS lock
the reason it crashed was because it had nothing for the downwards sensors to relate to till it got a GPS lock ,probably because the ground was completely white from the snow,so it just had nothing to reference to know where it was
 

DroneFilmmaker

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@DroneFilmmaker you should not have taken off in vision mode ,you should always make sure you have a GPS lock
the reason it crashed was because it had nothing for the downwards sensors to relate to till it got a GPS lock ,probably because the ground was completely white from the snow,so it just had nothing to reference to know where it was
I've done it many times without a single issue. Vision mode IS supposed to work AFAIK. I use it many times to get a higher point to get GPS satellites.

Anyhow, even if there was nothing for the sensors to relate to it should not start flying in one direction at the speed it was going before even completely leaving my hand. There are gyros and accelerometers inside these things that should be able to (and can) hold it fairly steady given to wind. I've flown non GPS quads (only 6 axis gyro) and they don't just go randomly flying off in some direction like this unless there is a serious problem with the gyros. If it had simply been in "ATTI mode" (or something like it) I would have had no problem compensating for any drift caused by wind etc. When it took off it flew so fast that it hit the house before I had time to react and try to compensate with the controls.

The only thing that I can think of is that the vision system was actually confused by the snow, not just no useful data, but something in the data made it think it needed to move, and move FAST, in one direction.

Has anyone else had weird issues with the VPS when flying over snow?
 

SkyeHigh

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I’d strongly recommend using a landing pad when taking off in snow for several reasons:

1. It keeps the aircraft clear from moisture (as does a hand launch)
2. It gives a clear visual reference for the downward facing vision system
3. It gives a flat and ideally level surface so the aircraft isn’t fighting to correct it’s level immediately on takeoff (and landing)

If the sun is out and reflecting strongly on the snow it can affect the obstacle avoidance system.
 

Meta4

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Anyhow, even if there was nothing for the sensors to relate to it should not start flying in one direction at the speed it was going before even completely leaving my hand.
The manual for your drone lists the conditions that create problems for the VPS system.

The performance of the Forward and Downward Vision Systems are affected by the surface being flown over.
Operate the aircraft with great caution in the following situations:
  • Flying over monochrome surfaces (e.g. pure black, pure white, pure red, pure green).
  • Flying over a highly reflective surfaces.
  • Flying at high speeds of over 22mph (36kph) at 2 meters or over 11mph (18kph) 1 meter.
  • Flying over water or transparent surfaces.
  • Flying over moving surfaces or objects.
  • Flying over inclined surfaces that will deflect sound waves away from the aircraft.
  • Flying over small and fine objects (e.g. tree branches and power lines). Flying in an area where the lighting changes frequently or drastically.
  • Flying over extremely dark (lux < 10) or bright (lux > 100,000) surfaces.
  • Flying over surfaces that can absorb sound waves (e.g. thick carpet).
  • Flying over surfaces without clear patterns or texture. Flying over surfaces with identical repeating patterns or textures (e.g. tiling).

Flying over snow ticks several of those boxes and if the VPS is getting patchy data, the drone won't stay still as it attempts to lock onto something.
But the VPS and snow is only one possible cause for what you described.
It would be necessary to see the recorded flight data to work out if it was the one that caused the issue in this incident.

If you want to find out ...
Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report on the flight data.
Come back and post a link to the report it provides.

Or just post the .txt file.
 
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DroneFilmmaker

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I’d strongly recommend using a landing pad when taking off in snow for several reasons:

1. It keeps the aircraft clear from moisture (as does a hand launch)
2. It gives a clear visual reference for the downward facing vision system
3. It gives a flat and ideally level surface so the aircraft isn’t fighting to correct it’s level immediately on takeoff (and landing)

If the sun is out and reflecting strongly on the snow it can affect the obstacle avoidance system.
That's probably a good idea. I almost always hand launch, snow or no snow, because I'm often flying from places where that's the only good option, even with a landing pad.

The sun actually wasn't out, it was cloudy. Still could have caused a problem though.
 

DroneFilmmaker

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The manual for your drone lists the conditions that create problems for the VPS system.

The performance of the Forward and Downward Vision Systems are affected by the surface being flown over.
Operate the aircraft with great caution in the following situations:
  • Flying over monochrome surfaces (e.g. pure black, pure white, pure red, pure green).
  • Flying over a highly reflective surfaces.
  • Flying at high speeds of over 22mph (36kph) at 2 meters or over 11mph (18kph) 1 meter.
  • Flying over water or transparent surfaces.
  • Flying over moving surfaces or objects.
  • Flying over inclined surfaces that will deflect sound waves away from the aircraft.
  • Flying over small and fine objects (e.g. tree branches and power lines). Flying in an area where the lighting changes frequently or drastically.
  • Flying over extremely dark (lux < 10) or bright (lux > 100,000) surfaces.
  • Flying over surfaces that can absorb sound waves (e.g. thick carpet).
  • Flying over surfaces without clear patterns or texture. Flying over surfaces with identical repeating patterns or textures (e.g. tiling).

Flying over snow ticks several of those boxes and if the VPS is getting patchy data, the drone won't stay still as it attempts to lock onto something.
But the VPS and snow is only one possible cause for what you described.
It would be necessary to see the recorded flight data to work out if it was the one that caused the issue in this incident.

If you want to find out ...
Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report on the flight data.
Come back and post a link to the report it provides.

Or just post the .txt file.
I can definetly see how snow could cause a problem. I should have mentioned however, that the snow was not covering the ground completely. I am starting to suspect it is something other than the VPS. Anyhow... I'll post the flight logs. I can also get the .DAT files if those are helpful.
 

boblui

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drone it took off quite fast to the side and crashed into the side of the house.
Even when the GPS and vision sensors are not usable, there is always the IMU which, if functioning normally, should keep the craft from moving too much on it's own. I would suggest you to post the .DAT flight log file which contains raw sensor data. The .TXT file may not tell much in such circumstance.
 
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DroneFilmmaker

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Here is the Phantom Help link and .TXT file. DJI Flight Log Viewer - PhantomHelp.com

One thing I noticed looking at it is that it shows a 100% stick input in the direction it crashed (which I do not remember doing), but there are none of the crash errors and such that I would expect.
 

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Meta4

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Here is the Phantom Help link and .TXT file. DJI Flight Log Viewer - PhantomHelp.com

One thing I noticed looking at it is that it shows a 100% stick input in the direction it crashed (which I do not remember doing), but there are none of the crash errors and such that I would expect.
Looking a little deeper into the flight data, there's a lot of joystick input in all 4 axes.
The stick inputs are more than enough to cause the incident as described.

The green indicates when the stick was centred
Yellow = stick pulled down or pushed left
Red = sticked pushed up or pushed right.

 
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boblui

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After starting the motors only the elevator input was released but not the aileron. Since you were hand launching, I would imagine that you held the craft with the right hand and the controller with the left hand so that you could manipulate the throttle stick. That means you were probably pushing the elevator/ aileron stick with your body. Is it possible that the stick was still being pressed against after the motors were started ? Otherwise, there may be some problems with the stick modules of the RC.

1606875182116.png
 
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DroneFilmmaker

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After starting the motors only the elevator input was released but not the aileron. Since you were hand launching, I would imagine that you held the craft with the right hand and the controller with the left hand so that you could manipulate the throttle stick. That means you were probably pushing the elevator/ aileron stick with your body. Is it possible that the stick was still being pressed against after the motors were started ? Otherwise, there may be some problems with the stick modules of the RC.

View attachment 118267
I think this is it. Just replaying what could have happened I think that is the most likely scenario. I was wearing thin gloves and I think that they may have caught on the right stick when I thought I had released it and pulled it toward the left. I'll have to keep a sharp eye on this in the future!

Thanks everyone for your help figuring out what happened.
 
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DroneFilmmaker

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I also gave the gimbal a closer inspection and one of the ribbon cables in completely broken off. Now to fix or replace....
 

pdipasquale

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I was taking the MP for a second flight to film the snowfall this morning and had a crash at takeoff. I was hand launching it about 10 feet from our house (which I do all the time) and as I started the props and let go of the drone it took off quite fast to the side and crashed into the side of the house. It hit hard enough to make a couple holes in the vinyl siding and even made a small hole in the aluminum downspout. Folded both of the front arms back against the body and shredded 3 of the props.

It looked like everything else was good, but on a more thorough inspection it seems like it messed up the gimbal. Visually it looks fine, but on the phone it shows a gimbal overload error and there is no video feed. It also doesn't go through the "gimbal dance" on startup.

So my questions are:
#1 What would have caused it to fly into the side of the house on its own? It wasn't wind since there wasn't much wind and it definitely was not moving that fast. It wasn't accidentally moving the sticks because I only had my hand on the left stick and the other one was holding the drone. I can't imagine it was compass interference because I've taken off from this spot dozens of times with no issues, and I had actually flown from there about an hour earlier. The only thing I can think of is that it was in VISION mode (hadn't gotten GPS yet) but I take off in Vision mode all the time without any problems. Could the snow have been messing something up?

#2 What is going on with the gimbal? Is it the ribbon cable or possibly something else?

Thanks everyone!
 

Cyber3xpert

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I also gave the gimbal a closer inspection and one of the ribbon cables in completely broken off. Now to fix or replace....
The ribbon cables are almost impossible to "fix;" I'd advise just buying a new cable. But do be careful that while taking the gimbal apart you do not stress it in any direction, as this could mess up the tiny motors inside it. Also, the screws holding the gimbal housing on may be strangely tight, but be as gentle as possible, for the reason stated above.
 
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DroneFilmmaker

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The ribbon cables are almost impossible to "fix;" I'd advise just buying a new cable. But do be careful that while taking the gimbal apart you do not stress it in any direction, as this could mess up the tiny motors inside it. Also, the screws holding the gimbal housing on may be strangely tight, but be as gentle as possible, for the reason stated above.
By fix, I meant replace the ribbon cable. I can't imagine how it could be repaired after it's broken without some special-purpose machine. Definitely will be careful with the disassembly and repair
 
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MavicAir2Marc

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I've had something similar happen before when going through a tight garden, holding it (to use as a steady cam, too many obstacles in that area). My plan was to walk it through the garden (an assistant was walking it through whilst I concentrated on the controls) then let it go to a reveal on the side of the church...as soon as the assistant let it go, it went wildly flying off backward and to the right, ending up in a low tree. I was giving it throttle at the time so I'm sure that has something to do with it. Needless to say I wouldn't try that again except in an open area.
 

mikereidphotography

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I’d strongly recommend using a landing pad when taking off in snow for several reasons:

1. It keeps the aircraft clear from moisture (as does a hand launch)
2. It gives a clear visual reference for the downward facing vision system
3. It gives a flat and ideally level surface so the aircraft isn’t fighting to correct it’s level immediately on takeoff (and landing)

If the sun is out and reflecting strongly on the snow it can affect the obstacle avoidance system.
Absolutely on this. My experiences yesterday in the snow convinced me to order one when I got home. Also prevents taking off with a clump of snow on the downward sensors :)
 

shb

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I've done it many times without a single issue. Vision mode IS supposed to work AFAIK. I use it many times to get a higher point to get GPS satellites.

Anyhow, even if there was nothing for the sensors to relate to it should not start flying in one direction at the speed it was going before even completely leaving my hand. There are gyros and accelerometers inside these things that should be able to (and can) hold it fairly steady given to wind. I've flown non GPS quads (only 6 axis gyro) and they don't just go randomly flying off in some direction like this unless there is a serious problem with the gyros. If it had simply been in "ATTI mode" (or something like it) I would have had no problem compensating for any drift caused by wind etc. When it took off it flew so fast that it hit the house before I had time to react and try to compensate with the controls.

The only thing that I can think of is that the vision system was actually confused by the snow, not just no useful data, but something in the data made it think it needed to move, and move FAST, in one direction.

Has anyone else had weird issues with the VPS when flying over snow?
I would aways get GPS lock before I took off.
 
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