Hi everyone,

I took my drone out to the Smokey Hollow Falls in Hamilton, Ontario to get some nice drone footage of the waterfall. Roughly 10 seconds after taking of, my Mavic Air started drifting right in front of the water fall. My left joystick had little to no input so it raised elevation very slowly even I pushed the joystick as high could. Somehow, I managed to counteracct tge drifting motion by pointing the right joystick in the opposite direction it was drifting. I almost got it to the lookout deck before I suddenly could not controll it. It hit the railing head on and fell right beside the 10 meter waterfall. Could not retireive it. Bought the drone second hand and had no prior issues. Flew the drone 1.75 km out just a few days prior. Contacted DJI support and they sayed I ran out of warranty and would have to pay a $65 fee to do an "analysis check" of the drone.
Here are what I think could be the Drone malfunction:
1. Drifting- had no prior problem
2. Little to no input to raise altitude on left hand throttle
3. Front obstacle avoidance did not work even though the bars were 4 inches in diameter- I know i should not count on obstacle avoidance


What do you guys think I should do?


P.S flew an alpine white Mavic Pro before the Mavic Air

Hi there, I'm sorry to hear about the accident. For fly safety consideration, you are recommended to send it in for a thorough diagnosis. Kindly please contact our support team via http://www.dji.com/support  to open a case and then send it in, we'll do our best to help this out. By the way, since your drone has been out of the warrenty period, you need to bear the repair cost yourself. Thanks for your kind understanding.

I would recommend to post your flight logs for some experts to view but it sounds like it did not have a gps lock and was in atti mode or it could have picked up a compass interference

Here are what I think could be the Drone malfunction:
1. Drifting- had no prior problem
2. Little to no input to raise altitude on left hand throttle
3. Front obstacle avoidance did not work even though the bars were 4 inches in diameter- I know i should not count on obstacle avoidance

What do you guys think I should do?
Your description sounds to me like the issue was something quite different.
I think that looking at the recorded flight data will probably show that what you've guessed isn't what really happened.

If you do want to know, go to http://www.phantomhelp.com/LogViewer/Upload/
It has instructions to find the .txt file from your phone or tablet which you can upload to that site
Upload it and it gives you a summary of the flight data.
Post a link to that summary.

Or just post the .txt file

https://www.phantomhelp.com/LogViewer/46Y50Z6QZHSUZPRHKEF9

spiderman1928 Posted at 8-6 05:52
https://www.phantomhelp.com/LogViewer/46Y50Z6QZHSUZPRHKEF9

By now you've had a chance to look at the Phantomhelp summary and saved yourself paying for an official analysis.
You'll note that the drone had no GPS at all for the entire flight because it was carried out in an area without a clear skyview.
Without GPS, the drone had no ability to hold position and had no brakes.
And obstacle avoidance isn't able to work either.

For some of the flight you might have had some stabilisation from the downward facing sensors, but only where there was sufficient lighting and the surface below the drone was close enough.
Where VPS stabilisation was not possible you were completely on your own in atti mode.

If you haven't flown in atti mode, this might feel like the drone isn't responding to joystick input.
Atti mode is fine out in the open.

The message is that the incident wasn't due to any hardware or software issue.
But learning to fly in atti mode in tight quarters with obstacles is asking for trouble.

spiderman1928 Posted at 8-6 05:52
https://www.phantomhelp.com/LogViewer/46Y50Z6QZHSUZPRHKEF9

Hi Spiderman,

Unlucky flight....

Your drone did start in OPTI mode ; enough light for OPTI, stabilized P-GPS not possible due to zero GPS reception!
OPTI > ATTI > OPTI etc   see your details in my chart.

It is kind of difficult to control a drone in ATTI in confined area, even for experienced flyers.

Few messages in the app did warn you.Sorry for your loss.

Always wait for a GPS lock, do before and after take-off some checks, than this would not have happend.

PS even if you could manage to fly in ATTI, max height is limiting to go up again ! This after short moment in P-GPS, after that again OPTI/ATTIThis will reset the max height in this mode.  (few pilots more lost there drone like this)

cheers
JJB

Oh well, thanks for your help. Probably going to buy a new drone body or just sell the remaining accessories.

spiderman1928 Posted at 8-6 05:52
https://www.phantomhelp.com/LogViewer/46Y50Z6QZHSUZPRHKEF9

I just spotted one interesting feature in the data.
I wrote the previous post too quickly without looking at everything in the spreadsheet.

At 1:13.5 you went full forward with the left stick and held it for 12 seconds.
The drone only rose 2 metres in that time and I can't see a reason for that slowness.
That matches with what you said about it not responding to full throttle.
I wonder what was going on there?

Yes, was very worried when I couldn't raise the elevation of my drone by much, even though I raised my throttle to the max.

Labroides Posted at 8-6 06:14
I just spotted one interesting feature in the data.
I wrote the previous post too quickly without looking at everything in the spreadsheet.

Max Altitude Approached. Wait for the GPS satellite signal recovery before ascend. at -6.2 meter  (56secs)
So no chance of getting higher!

spiderman1928 Posted at 8-6 06:16
Yes, was very worried when I couldn't raise the elevation of my drone by much, even though I raised my throttle to the max.

The issue was complicated by VPS drifting in and out.
Here's the relevant section of the manual (from p 48)
   Height is restricted to 16 feet (5 meters) when the GPS signal is weak and Downward Vision System is activated.
   Height is restricted to 98 feet (30 meters) when the GPS signal is weak and Downward Vision System is inactivated.
When there was no VPS, the altitude limit is 30 metres, but when the drone is over a suitable surface for VPS, the altitude limit is only 5 metres.
And it's not spelled out in the manual but apparently that 5 metres is from the surface below the drone, rather than from the home point as all other altitudes are.
So .. when the drone was picking up a surface below, it could only climb to 5 metres above that.
But if there was no suitable VPS surface, the drone could have climbed normally to 30 metres (and that would have been above the launch point.
Confusing and the first time I've run into this complicated scenario.

So, I'm assuming this is pilot error, right?

spiderman1928 Posted at 8-6 06:44
So, I'm assuming this is pilot error, right?

Yes ... it all comes down to the pilot's choice to fly in that environment

Ok, disappointing that I spent $800 on a drone that hugely depends on it environment. Control range is 4 km at best, couldn't fly it 10 meters out.

spiderman1928 Posted at 8-6 07:15
Ok, disappointing that I spent $800 on a drone that hugely depends on it environment. Control range is 4 km at best, couldn't fly it 10 meters out.

Hi spiderman,

Understand your dissapointment, what happend to your MA is a) because starting a flight with no GPS lock and b) beacuse it it hard to know and understand all what is written in the manual.

As Labroides point out the pages in the manual, for better understanding the next text.

5 meter max height limit is measured by the VPS bottom height sensor, the 30 meter max height limit is done by the barometric sensor.

This max height is limited when a flight starts in OPTI or ATTI mode. (as in your flight)
Flying on a level plane field the 5 meter is thus always above the starting position.

But what happend if you fly away and lower your craft along a hill....
See my simple drawing.

When moving away from point A towards B the barometric height goes minus, the VPS height gets out of range (drwaing not to scale...) and into range again at point B.  At that point where i.e. VPS height is measuring/indicating 4 meter ; craft can only climb 1 meter beacuse of the 5 meter limit!

Same happens if you fly down into a canyon on P-GPS, if after lowering the GPS signals are not received (craft into OPTI or ATTI) and VPS height is measuring....5 meter limit is active AND not possible to fly higher than 5 meter!

DJI should change this in their software!  Easy does the trick ; when barometric height measurement is lower that the take-off height > disable this max 5 meter VPS height limit !! (30 meter limit is not a problem as the reference height is zero at takeoff)

Don`t stop flying drones, its a great hobby    only the learning curve can be a steep one...

cheers
JJB

Thanks, but not paying $800 to replace this drone.

...........

Thanks for all the help.