Out of control drone crash

[RokkoRokko]

Had a major scare with my new Mavic 2 Pro yesterday.

I have my craft setup so that unless I am operating the control sticks the Mav will just hover.

I launched, as have done many times in the last 2 weeks with no issue

I went to rise and the message returned, Maximum height reached, but it was only like 5 or 6 meters high

I then hit the focus button on the controller and the Mav started moving to the right straight away, slow at first, and then started descending

I tried to control it and rotated 180 degrees but continued moving right fast [opposite direction as I had rotated.

I rotated again and clipped a tree, resulting in a flash, and the Mav fell to the ground below the tree, 22 seconds after the focus push set this event in motion.

I was very lucky as the Mav was undamaged, but am now nervous as have lost a bit of trust, especially after research has shown others have had the same experience, their Mav 2 suddenly doing its own thing

I am appreciative of my luck, as those guys lost their drones.

I did a test flight in my apartment a few minutes afterwards and all was completely normal.

Points to note,

Because I had been flying inside earlier I had obstacle avoid off and was in Tripod mode.

The low maximum height warning seems significant to this, somehow, as it was the first indication something was not normal

Any ideas?

Could this have been an 'Atti' mode thing, like maybe I launched without GPS lock without realizing?

 

[parkgt]

Had a major scare with my new Mavic 2 Pro yesterday.

Just as in every case that someone has something strange happen during flight; posting the flight log(s) is the best way to get help.

Post the log!

Also don't know what you mean by:

"I have my craft setup so that unless I am operating the control sticks the Mav will just hover."

That is the default behavior of almost all drones these days.

 

[RokkoRokko]

Just as in every case that someone has something strange happen during flight; posting the flight log(s) is the best way to get help.

Post the log!

Also don't know what you mean by:

"I have my craft setup so that unless I am operating the control sticks the Mav will just hover."

That is the default behavior of almost all drones these days.

Cheers for quick reply

I am still learning re this but thought the 'hover when sticks not being used' was an option I could change [which i'd never want to]

How do I access and post the log

 

[sar104]

Cheers for quick reply

I am still learning re this but thought the 'hover when sticks not being used' was an option I could change [which i'd never want to]

How do I access and post the log

Start here:

How to retrieve a TXT log: DJI Flight Log Viewer | Phantom Help

 

[Not A Speck Of Cereal]

Yes, post the logs.

I then hit the focus button on the controller and the Mav started moving to the right straight away, slow at first, and then started descending

Just to be sure, you mean the physical button on the controller, not the focus indicator on the screen, yes?

Could this have been an 'Atti' mode thing, like maybe I launched without GPS lock without realizing?

You should already know the answer to this. Having a Good to Go (green) title bar and GPS mode indication is something you need to look at every time you lift off the ground. Even if you don't have a flight checklist, you should be taking a quick look at the top row of DJI GO for GPS status, satellites count, battery power / health, and other indicators / warnings (such as compass / magnetic interference, airport restriction warnings, etc.).

If it were in ATTI mode, you would have seen that (yellow status bar, ATTI MODE text, ATTI MODE voice alert).

Chris

 

[RokkoRokko]

Yes, the physical controller button

This is my flight record for this incident

As I suspected it went to ATTI mode but I don't understand why the GPS was weak -

It started with GPS

Then even with 6 satellites registered it flipped to Atti

I wasn't watching my controller as once the Mav stopped hovering I was watching that

the max height thing I mentioned is in the log, but have no idea why it deceided it was at max height at that point

 

[sar104]

Yes, the physical controller button

This is my flight record for this incident

As I suspected it went to ATTI mode but I don't understand why the GPS was weak -

It started with GPS

Then even with 6 satellites registered it flipped to Atti

I wasn't watching my controller as once the Mav stopped hovering I was watching that

the max height thing I mentioned is in the log, but have no idea why it deceided it was at max height at that point

You launched with only 6 locked satellites, and a navHealth of zero. It requires 7 or 8 minimum to use for navigation. The aircraft was stable in P-mode initially, but via the vision system, not GPS, until it climbed out of vision range, at which point it switched to ATTI.



Did you not notice the lack of a home point notification and the ATTI mode warning at 40 seconds:

"Weak GPS signal. Aircraft is in Attitude mode and hovering may be unstable. Fly with caution."

 

[RokkoRokko]

You launched with only 6 locked satellites, and a navHealth of zero. It requires 7 or 8 minimum to use for navigation. The aircraft was stable in P-mode initially, but via the vision system, not GPS, until it climbed out of vision range, at which point it switched to ATTI.

View attachment 85171

Did you not notice the lack of a home point notification and the ATTI mode warning at 40 seconds:

"Weak GPS signal. Aircraft is in Attitude mode and hovering may be unstable. Fly with caution."

Cheers broz,

Ahhh, the pain of being a noobi grommet

I am grateful for my extreme luck in this....

....to still have a working drone after a tree impact to ground crash
….& thanks to you broz analysis, to know exactly what happened so I know better for next time

I had wondered what the P-GPS was about - thought it was GPS in 'P' mode..... so it was total reliance on vision systems

I wont launch again til I know I have a healthy number of satellites locked in


No, I hadn't noticed the lack of home point and by the time that warning appeared I was watching the Mav trying to keep it from crashing so I didn't see it til I viewed the log

The whole thing appeared to take only a few seconds but it took 22 seconds from the time it started drifting to ground impact, after I watched the video back

I suspect one of the reasons I still have a drone is that it wasn't a dead fall after clipping the tree... the video suggests a semi-soft landing suggesting the aircraft was still trying to fly
I'm just grateful it did clip the tree as it was accelerating and if it had gone further the impact speed would have too high to not have serious damage

Learning the hard way is a harsh mistress, I am so grateful for my luck in this, as my fear of flying again is gone now I know what happened.
Its so important to know why something goofs up
Time for more homework.

How did you produce that image from the data - I would like to be able to generate that for myself

Thanks again for your help & analysis broz.

Cheers

Zakk

 

[DanMan32]

Ah, no GPS, in VPS/Vision mode. That explains the maximum altitude reached message at such a low altitude. That should have prevented getting out of VPS range and into ATTI mode. Perhaps GPS briefly kicked in, allowing him to ascend outside of VPS range?

 

[RokkoRokko]

Ahh, Not quite
I had launched from my 2nd story window
so the VPS was fine until the Mav passed over the sidewalk canopy outside my window and suddenly the ground was several meters further down.
It hovered for a second then went downwards, out of my line of sight
being a grommet flyer I panicked and rushed to control the Mav went it went downwards and that's when it started moving sideways fast

There was 20 seconds from beginning to drift til it hit the tree
If I had kept my head it would have likely settled to a hover, but not knowing what was going on, or even that it had lost GPS [I didn't realize 6 satellites wasn't enough] I over-reacted

I was very lucky as my Mav was undamaged

Thanks to the broz' analysis above I am now more educated & my confidence is back

I now launch with around 13-17 satellites & have not had a problem since with control.
I also always ensure the home point has set

I'm getting awesome shots [I am a film maker]

With a lot of trees around [a park across the road from me and many trees on the road outside my apartment] I do get weak controller signal sometimes
I have an antennae booster set on the way to help with that.

This forum is awesome and the broz on it are very helpful

much, much appreciated