DJI-Ken Posted at 2016-12-5 14:52
I've only looked at the last flight, the aircraft was already at 6m at 7:51 when you gave it a very quick (not held down) on the throttle stick. Then at 7:52 it hit the tree. I think if it wouldn't have hit the tree it would have started to descend but the time from when you tapped the stick down and it hitting the tree was too quick.
I will look at another flight, star the flight and re-sync and and tell me what minute and second mark to start watching.

If you want an example of the unresponsive down / "Landing" mode behavior take a look at 3:40 @ 114m and 4:48 @ 77m on the crash flight. You can also see this behavior on most of my flights. Can you provide insight on what could be causing this?

MSavage Posted at 2016-12-5 13:19
If you want an example of the unresponsive down / "Landing" mode behavior take a look at 3:40 @ 114m and 4:48 @ 77m on the crash flight. You can also see this behavior on most of my flights. Can you provide insight on what could be causing this?

The few meter altitude gain at 3:40 is from going full throttle to stop sometimes the altitude will change a little bit as the barometer may be compensating from high speed to a stop.
And the lowering in altitude at 4:48 is from the aircraft entering landing mode so it started to descend then a few seconds later you cancelled landing.

I did have the data analysis team review the flight from the app and they said the aircraft is operating as it should. If you put something under the aircraft from that low of an altitude it will raise to keep the same distance from the ground.
But, they will review the flight data recorder when they receive it as that gives much more information and they will make a determination then.

DJI-Ken Posted at 2016-12-5 15:49
The few meter altitude gain at 3:40 is from going full throttle to stop sometimes the altitude will change a little bit as the barometer may be compensating from high speed to a stop.
And the lowering in altitude at 4:48 is from the aircraft entering landing mode so it started to descend then a few seconds later you cancelled landing.

Ken. My question is, why is the aircraft going into Landing Mode in the first place? Is it not possible to hit the left/down control without initiating a landing mode?

MSavage Posted at 2016-12-5 14:01
Ken. My question is, why is the aircraft going into Landing Mode in the first place? Is it not possible to hit the left/down control without initiating a landing mode?

Let's just wait to see when the flight data recorder says as there's not enough data given by the app flight record.

If you were already having issues with the controls, why would you fly it at all? Am I crazy in thinking that the first sign of issues is grounds to stop flying and send it in for repair?

Not saying you deserved to have it fly into a tree branch, but I find it funny you start by saying you were already have one problem and then, because of your first problem, it crashed. When, in reality, it's because you decided to fly it again KNOWING it already had issues.

TrevHolland Posted at 2016-12-5 18:31
If you were already having issues with the controls, why would you fly it at all? Am I crazy in thinking that the first sign of issues is grounds to stop flying and send it in for repair?

Not saying you deserved to have it fly into a tree branch, but I find it funny you start by saying you were already have one problem and then, because of your first problem, it crashed. When, in reality, it's because you decided to fly it again KNOWING it already had issues.

Hind sight is always 20/20. When I first reported my down control w/ "Landing Mode" issue on this forum. Most, including the the DJI Mods, suggested it was a calibration issue and to go ahead and recalibrate the controls and VPS. I'm not quite sure how I was supposed to see if that resolved the issue without actually flying the drone...but anyways.  

What I didn't know was that the Mavic will automatically gain altitude if a car passes 10' underneath it. Combine that with luck of being under a tree and with a control/software that appears to be buggy and you have a crash.

MSavage Posted at 2016-12-6 01:08
Hind sight is always 20/20. When I first reported the down control w/ "Landing Mode" on this forum. Most, including the the DJI Mods, suggested it was a calibration issue and to go ahead and recalibrate the controls and VPS. I'm not quite sure how I was supposed to see if that resolved my issue without actually flying the drone.  

What I didn't know what that the Mavic will automatically gain altitude if a car passes 10' underneath it. Combine that with bad luck of being under a tree and with a control/software that appears to be buggy and you have a crash.

I suppose if you were testing , you picked a really bad spot to do it, the outcome will be interesting I'm sure.

This really looks like the Mavic did what it should and as the car passed under it the Mavic compensated for the brief change in ground clearance...  sorry you crashed.

So what can we learn from this (besides the tree part)?  How can others stop something similar from happening if the down control wont override the automated ascent in that scenario?  Disable VPS?  Something else?

It must have been frustrating watching that thing in a controlled rise for 5-to-6 seconds before it hit the branch with no obvious way to stop it.

BuzzCut Posted at 2016-12-6 09:01
So what can we learn from this (besides the tree part)?  How can others stop something similar from happening if the down control wont override the automated ascent in that scenario?  Disable VPS?  Something else?

It must have been frustrating watching that thing in a controlled rise for 5-to-6 seconds before it hit the branch with no obvious way to stop it.

You can override the ascent, the ascent from it sensing the car was only a few seconds. The OP didn't give the  down stick input until it hit the tree branches.
So your last sentence is not correct.
If the OP will post a video of the flight record with the sticks overlaid you can see what I am talking about.

Thanks.  I was hoping that would be the case, and that the ascent could be interrupted at any time with a manual input.  I'd love to see the overlay here.

Also, the ascent appears to start while the car is still about 15-20 feet away from the underside of the Mavic.  So, do the bottom sensors actually propogate out like that?  Is there an approx angle of propagation?  It's of particular interest to me as I'm eagerly awaiting my Mavic and I have a number of use cases in mind where I'd want an object passing under - or close to under - the Mavic like that (a car being one of them).

BuzzCut Posted at 2016-12-6 10:21
Thanks.  I was hoping that would be the case, and that the ascent could be interrupted at any time with a manual input.  I'd love to see the overlay here.

Also, the ascent appears to start while the car is still about 15-20 feet away from the underside of the Mavic.  So, do the bottom sensors actually propogate out like that?  Is there an approx angle of propagation?  It's of particular interest to me as I'm eagerly awaiting my Mavic and I have a number of use cases in mind where I'd want an object passing under - or close to under - the Mavic like that (a car being one of them).

The OP said he gave the throttle a few blips to raise the drone up giving clearance for the car to pass under. When the drone is ascending before the car is under it, it was under his control. Then when the car passes underneath the VPS kicks in.

DJI-Ken Posted at 2016-12-6 10:15
You can override the ascent, the ascent from it sensing the car was only a few seconds. The OP didn't give the  down stick input until it hit the tree branches.
So your last sentence is not correct.
If the OP will post a video of the flight record with the sticks overlaid you can see what I am talking about.

How can he do that ? ( how can we all do that ) ?

I see what you're saying, but there appeared to be (after the multiple seemingly deliberate upward movements) a consistent slow and uninterrupted rise that lasted 5-6 seconds and started when the car was 15-20 feet away, hence the question about propagation.

Maybe that last 5-6 second rise was a combo of user input and VPS, but it appeared to be at a consistent and uninterrupted speed in the video, hence my ask.

BuzzCut Posted at 2016-12-6 12:50
I see what you're saying, but there appeared to be (after the multiple seemingly deliberate upward movements) a consistent slow and uninterrupted rise that lasted 5-6 seconds and started when the car was 15-20 feet away, hence the question about propagation.

Maybe that last 5-6 second rise was a combo of user input and VPS, but it appeared to be at a consistent and uninterrupted speed in the video, hence my ask.

It's actually closer to 40' because that's how wide the house lots are.. That's why I found it very strange indeed. I'm going to try to everlay the controls with the video. It happend very quickly but I swear I though there was enough time to have it reverse course.

Can't wait to see it.  I'll definitely learn something from this.  Sorry your Mavic got busted.

MSavage Posted at 2016-12-6 19:04
It's actually closer to 40' because that's how wide the house lots are.. That's why I found it very strange indeed. I'm going to try to everlay the controls with the video. It happend very quickly but I swear I though there was enough time to have it reverse course.

That's the thing with drones when you brake and try to reverse, there will always be a certain amount of continuous movement in the direction they were heading before braking, it takes a bit of getting used to, especially in close quarters.

Alansin Posted at 2016-12-6 10:47
How can he do that ? ( how can we all do that ) ?

By lowering the throttle.

hallmark007 Posted at 2016-12-6 13:52
That's the thing with drones when you brake and try to reverse, there will always be a certain amount of continuous movement in the direction they were heading before braking, it takes a bit of getting used to, especially in close quarters.

I realize that. I have compared the time stamp on the video with the flight data and I'm pretty sure the lower throttle command was done with enough time to reverse course. At worst, too close to call.

I have, like a few other on the forum, been experiencing a 'lower throttle' issue. The aircraft is unresponsive to a lower throttle input and subsequently enters a "Landing" mode.  

Here is a video from a fellow mavic user.


Sample of the data from the flight showing unresponsive lower throttle:

latitude	longitude	ascent(feet)	speed(mph)	time(millisecond)	time(second)	max_speed(mph)	rc_elevator	rc_aileron	rc_throttle	voltageCell2	flycState	message
45.40675706	-75.647071	380.57744	0.223694	224300	224.3	21.17040016	1024	1024	1024	4.02067	GPS_Atti
45.40675706	-75.647072	380.57744	0.223694	224400	224.4	21.17040016	1024	1024	1024	4.02067	GPS_Atti
45.40675709	-75.647072	380.57744	0	224500	224.5	21.17040016	1024	1024	883	4.02067	GPS_Atti
45.40675714	-75.647072	380.249356	0	224600	224.6	21.17040016	1024	1024	693	4.02067	GPS_Atti
45.40675718	-75.647072	380.249356	0	224700	224.7	21.17040016	1024	1024	651	3.97033	GPS_Atti
45.4067572	-75.647072	380.249356	0	224800	224.8	21.17040016	1024	1024	651	3.97033	GPS_Atti
45.40675725	-75.647072	380.57744	0	224900	224.9	21.17040016	1024	1024	653	3.97033	GPS_Atti
45.40675731	-75.647073	380.57744	0	225000	225	21.17040016	1024	1024	603	3.97033	GPS_Atti
45.40675739	-75.647073	380.57744	0	225100	225.1	21.17040016	1024	1024	568	3.97033	GPS_Atti
45.40675744	-75.647073	380.57744	0	225200	225.2	21.17040016	1024	1024	544	3.97033	GPS_Atti
45.40675754	-75.647073	380.57744	0	225300	225.3	21.17040016	1024	1024	571	3.97033	GPS_Atti
45.40675762	-75.647073	380.905524	0	225400	225.4	21.17040016	1024	1024	648	3.97033	GPS_Atti
45.40675771	-75.647073	380.905524	0	225500	225.5	21.17040016	1024	1024	635	3.97033	GPS_Atti
45.40675778	-75.647074	381.233608	0	225600	225.6	21.17040016	1024	1024	581	3.97033	GPS_Atti
45.40675788	-75.647074	381.233608	0	225700	225.7	21.17040016	1024	1024	526	3.98233	GPS_Atti
45.40675796	-75.647074	381.561692	0	225800	225.8	21.17040016	1024	1024	528	3.98233	GPS_Atti
45.40675808	-75.647074	381.889776	0	225900	225.9	21.17040016	1024	1024	540	3.98233	GPS_Atti
45.40675818	-75.647074	382.21786	0	226000	226	21.17040016	1024	1024	478	3.98233	GPS_Atti
45.40675829	-75.647074	382.21786	0	226100	226.1	21.17040016	1024	1024	461	3.98233	GPS_Atti
45.40675837	-75.647074	382.545944	0	226200	226.2	21.17040016	1024	1024	453	3.98233	GPS_Atti
45.40675844	-75.647074	382.874028	0	226300	226.3	21.17040016	1024	1024	404	3.98233	GPS_Atti
45.40675849	-75.647074	383.202112	0	226400	226.4	21.17040016	1024	1024	364	3.98233	GPS_Atti
45.40675858	-75.647074	383.530196	0	226500	226.5	21.17040016	1024	1024	364	3.98233	GPS_Atti
45.40675869	-75.647074	383.85828	0	226600	226.6	21.17040016	1024	1024	364	3.98233	GPS_Atti
45.40675881	-75.647075	383.85828	0	226700	226.7	21.17040016	1024	1024	364	4.02267	GPS_Atti
45.40675891	-75.647075	384.186364	0	226800	226.8	21.17040016	1024	1024	364	4.02267	GPS_Atti
45.40675902	-75.647075	384.514448	0	226900	226.9	21.17040016	1024	1024	364	4.02267	GPS_Atti
45.40675909	-75.647075	384.514448	0	227000	227	21.17040016	1024	1024	378	4.02267	GPS_Atti
45.40675917	-75.647075	384.842532	0	227100	227.1	21.17040016	1024	1024	389	4.02267	GPS_Atti
45.40675924	-75.647075	385.170616	0	227200	227.2	21.17040016	1024	1024	404	4.02267	GPS_Atti
45.40675933	-75.647075	385.170616	0	227300	227.3	21.17040016	1024	1024	406	4.02267	GPS_Atti
45.40675941	-75.647075	385.4987	0	227400	227.4	21.17040016	1024	1024	406	4.02267	GPS_Atti
45.4067595	-75.647075	385.826784	0	227500	227.5	21.17040016	1024	1024	406	4.02267	GPS_Atti
45.40675956	-75.647075	385.826784	0	227600	227.6	21.17040016	1024	1024	408	4.02267	FORCE_LANDING	Obstacle Sensing will be disabled when   landing. Land with care.
45.40675965	-75.647075	386.154868	0	227700	227.7	21.17040016	1024	1024	403	4.084	FORCE_LANDING
45.40675971	-75.647075	386.154868	0	227800	227.8	21.17040016	1024	1024	403	4.084	FORCE_LANDING
45.40675979	-75.647075	386.154868	0	227900	227.9	21.17040016	1024	1024	403	4.084	FORCE_LANDING
45.40675984	-75.647075	385.826784	0	228000	228	21.17040016	1024	1024	403	4.084	FORCE_LANDING
45.4067599	-75.647075	385.826784	0	228100	228.1	21.17040016	1024	1024	406	4.084	FORCE_LANDING
45.40675996	-75.647075	385.826784	0	228200	228.2	21.17040016	1024	1024	430	4.084	FORCE_LANDING
45.40676002	-75.647075	386.154868	0	228300	228.3	21.17040016	1024	1024	464	4.084	FORCE_LANDING
45.40676008	-75.647075	386.154868	0	228400	228.4	21.17040016	1024	1024	589	4.084	FORCE_LANDING
45.40676017	-75.647075	386.154868	0	228500	228.5	21.17040016	1024	1024	889	4.084	FORCE_LANDING
45.40676025	-75.647075	386.154868	0	228600	228.6	21.17040016	1024	1024	1024	4.084	FORCE_LANDING
45.40676034	-75.647075	386.154868	0	228700	228.7	21.17040016	1024	1024	1024	4.048	FORCE_LANDING
45.40676041	-75.647075	386.154868	0	228800	228.8	21.17040016	1024	1024	1024	4.048	FORCE_LANDING
45.4067605	-75.647075	386.154868	0	228900	228.9	21.17040016	1024	1024	1024	4.048	FORCE_LANDING
45.40676058	-75.647075	385.826784	0	229000	229	21.17040016	1024	1024	1024	4.048	FORCE_LANDING

This must have been caused by thermal wind..

MSavage Posted at 2016-12-6 21:48
I realize that. I have compared the time stamp on the video with the flight data and I'm pretty sure the lower throttle command was done with enough time to reverse course. At worst, too close to call.

I have, like a few other on the forum, been experiencing a 'lower throttle' issue. The aircraft is unresponsive to a lower throttle input and subsequently enters a "Landing" mode.  

I do actually see where your coming from, and maybe it's a 50/50 thing and I really hope they sort it out, but really lessons need to be learnt if you had a problem, then try to sort it , not a good idea to put yourself in a position that can go so wrong when you already know there may very well be a problem, may just be better get it sorted before and be happy that the drone will 100% respond to commands and you can feel confident using in such situations.
Good Luck

DJI Ken, any ideas on the propagation of the lower sensors?  I think that's around 65*  That's quite a large field, even if that's the max.  That would mean that you could be in your front yard and a car could be passing or turning on the street near you and cause ascent.  Maybe that's required for Terrain Follow to be effective?  Seems pretty far reaching.

MSavage Posted at 2016-12-7 04:48
I realize that. I have compared the time stamp on the video with the flight data and I'm pretty sure the lower throttle command was done with enough time to reverse course. At worst, too close to call.

I have, like a few other on the forum, been experiencing a 'lower throttle' issue. The aircraft is unresponsive to a lower throttle input and subsequently enters a "Landing" mode.  

Also remember DJI does not use any 3rd party data analysis as they may not read everything correctly.
Just wait until the flight data recorder is analyzed and they will tell you exactly what happened.

If you post your flight log playback with the sticks overlaid like I suggested earlier, you can see that the aircraft hit the tree one second after you gave 100 full down.
7:51 100% down stick input, 7:52 it hot the tree and you also gave 100% full forward and 100% full right bank. That was is the first part of the second, then with the same second 7:52 you gave 100% full left bank and 100% full throttle down.
So you didn't give the down stick input soon enough as the Mavic was rising from the car going underneath it.
Again, the last several seconds of the flight and the crash looks to be user error from what I can see from reviewing your flight. And the flight data analysis department said the same thing as me.

If your aircraft had issues prior to the flight or even during the flight, the last several seconds of the flight, the Mavic flew as designed to fly and without any errors that I can see.
Hopefully when they analyze the flight they will have a different conclusion.

DJI-Ken Posted at 2016-12-7 03:39
By lowering the throttle.

srry, i meant how do we post a video where it shows your stick movement ?

Alansin Posted at 2016-12-8 07:22
srry, i meant how do we post a video where it shows your stick movement ?

You can upload your video to YouTube, then post the link here.

Heavysledz Posted at 2016-12-5 13:14
were you flying (hovering) directly above the street? If so, how high above the car was the drone when the car passed under it? I wonder if it sensed the abrupt change in altitude above the vehicle and in an attempt to avoid an obstacle, auto corrected upward into the tree?

This is exactly what I was wondering.    The quick movements would have been him.   The slow rise looked more like collision avoidance kicking in and raising the drone up because the car passed under it.

DJI-Ken Posted at 2016-12-8 09:54
You can upload your video to YouTube, then post the link here.

of course i can upload to you tube... i mean, how do i can post a video, where it also shows the overlay of my stick movement, or my route?

Alansin Posted at 2016-12-9 13:34
of course i can upload to you tube... i mean, how do i can post a video, where it also shows the overlay of my stick movement, or my route?

From the home page in the DJI GO 4.0 tap the + sign on the top right.
Then tap Flight Record, then scroll down to whichever flight you want to see and tap that then tap the RC icon and it will overlay your sticks, then tap play and that's it.