Anyone know what would have caused this sudden drop in altitude?  I was flying in my backyard mainly to drain a battery, but I noticed in several runs forward I was losing altitude and then on this final run I just dropped right into the ground.  This happened again on a strafe to the left, but I pulled up before I hit ground.  I was flying with metal fence and concrete around me and power lines above me, so I know right off the bat not ideal conditions and there were wind gusts that also maybe pushed me into the ground.  Log attached but I couldn’t see anything terribly wrong except a low compass value near impact, but no big voltage drops, etc. Maybe one of you can make sense of it.  I have flown two full batteries in different locations since this with caution and without incident, but now I am in fear of this thing dropping out of the sky on me.



Firmware .600 at crash, .700 without incident

Airdata log - http://app.airdata.com/main?share=ldyqPz

Assuming that it wasn't responding to your stick commands the behavior in the video certainly seems odd but also somehow vaguely familiar. My first thought was that something might have triggered the forward sensors, but there's nothing obvious in the video to explain it and your best bet is probably to upload the flight's DAT file to DropBox and post a link to it here.

Yes your environment was a disaster but I don't think it was the problem, looks like you were pushing down on the throttle causing craft to go straight down, you got warnings to let sticks back to centre point.
VPS may not be working on grass surface.

hallmark007 Posted at 2017-5-12 07:39
Yes your environment was a disaster but I don't think it was the problem, looks like you were pushing down on the throttle causing craft to go straight down, you got warnings to let sticks back to centre point.
VPS may not be working on grass surface.

I certainly don't remember throttling down and reviewing my flight control movements in the app doesn't show that either.  I did however throttle down when I hit the grass to turn off the motor.  I assumed the Braking error was because it was on/approaching the ground triggering the error.  Certainly could be the VPS going wonky though I guess.

Working on upload of the .DAT file now.

Had a hard time finding the right log.  I think this is it though.  Thanks for the help!

https://www.dropbox.com/s/bwbfihues0z9gk5/FLY021.DAT?dl=0

Reznor99 Posted at 2017-5-12 07:53
I certainly don't remember throttling down and reviewing my flight control movements in the app doesn't show that either.  I did however throttle down when I hit the grass to turn off the motor.  I assumed the Braking error was because it was on/approaching the ground triggering the error.  Certainly could be the VPS going wonky though I guess.

Working on upload of the .DAT file now.

I understand you may have throttled down when it landed, which means the Mavic was still running and still had power, so maybe something to do with VPS .
I think when droneflying refers to something vaguely familiar, he's referring to power cut of some sort,

hallmark007 Posted at 2017-5-12 08:03
I understand you may have throttled down when it landed, which means the Mavic was still running and still had power, so maybe something to do with VPS .
I think when droneflying refers to something vaguely familiar, he's referring to power cut of some sort,

It felt like power loss on each of those forward runs.  As soon as I pushed forward it would drop in altitude like I was losing power.  But like you said the motors were still running after I hit ground and it was more of a controlled/level drop into the grass, not a tumble or drop-like a stone.  I didn't see any voltage drops either.  This Mavic is a warranty replacement with a March manufacturing date so I was worried it might be in that bad batch experiencing power failures lately.

I had a similar experience. Mavic will descend at regular speed if you have VPS off or error when you throttle down using left stick.

Reznor99 Posted at 2017-5-12 07:55
Had a hard time finding the right log.  I think this is it though.  Thanks for the help!

https://www.dropbox.com/s/bwbfihues0z9gk5/FLY021.DAT?dl=0

I looked at this flight. In summary, the problem seems to be that the Mavic thought it was gaining altitude, but, it actually wasn't. In response it "corrected" for the percieved gain by losing altitude. At time 398 Barometer:raw was decreasing but Barometer:smooth, which is computed from Barometer:raw, was increasing. This seems to be an error. This can also be seen with relativeHeight which is then computed from Barometer:smooth. Note, that vpsHeight also shows the AC descending. Not shown are the motorCommanded data which are decreasing.
That's what happened. It's a mystery, to me at least, why Barometer:smooth started to increase. It should be just a simple smoothing algorithm applied to Barometer:raw to smooth it and make it acceptable for the purposes of maintaining altitude. I note that you're using firmware 01.03.0700. Maybe, we'll start seeing more of these.

BudWalker Posted at 2017-5-12 15:18
I looked at this flight. In summary, the problem seems to be that the Mavic thought it was gaining altitude, but, it actually wasn't. In response it "corrected" for the percieved gain by losing altitude. At time 398 Barometer:raw was decreasing but Barometer:smooth, which is computed from Barometer:raw, was increasing. This seems to be an error. This can also be seen with relativeHeight which is then computed from Barometer:smooth. Note, that vpsHeight also shows the AC descending. Not shown are the motorCommanded data which are decreasing.
That's what happened. It's a mystery, to me at least, why Barometer:smooth started to increase. It should be just a simple smoothing algorithm applied to Barometer:raw to smooth it and make it acceptable for the purposes of maintaining altitude. I note that you're using firmware 01.03.0700. Maybe, we'll start seeing more of these.

Thank you. I had looked at the file but couldn't figure out what had happened and appreciate the analysis.

BudWalker Posted at 2017-5-12 15:18
I looked at this flight. In summary, the problem seems to be that the Mavic thought it was gaining altitude, but, it actually wasn't. In response it "corrected" for the percieved gain by losing altitude. At time 398 Barometer:raw was decreasing but Barometer:smooth, which is computed from Barometer:raw, was increasing. This seems to be an error. This can also be seen with relativeHeight which is then computed from Barometer:smooth. Note, that vpsHeight also shows the AC descending. Not shown are the motorCommanded data which are decreasing.
That's what happened. It's a mystery, to me at least, why Barometer:smooth started to increase. It should be just a simple smoothing algorithm applied to Barometer:raw to smooth it and make it acceptable for the purposes of maintaining altitude. I note that you're using firmware 01.03.0700. Maybe, we'll start seeing more of these.

Interesting but scary. So firmware not calculating the height correctly. Hope it's not everyones Mavic.

thehippoz Posted at 2017-5-12 15:56
Interesting but scary. So firmware not calculating the height correctly. Hope it's not everyones Mavic.

I was messing around earlier similar flying no problems, I'm on 700..

Any reason you were discharging the battery to 30%?

hallmark007 Posted at 2017-5-12 16:00
I was messing around earlier similar flying no problems, I'm on 700..

Probably a fluke then hopefully.

BudWalker Posted at 2017-5-12 15:18
I looked at this flight. In summary, the problem seems to be that the Mavic thought it was gaining altitude, but, it actually wasn't. In response it "corrected" for the percieved gain by losing altitude. At time 398 Barometer:raw was decreasing but Barometer:smooth, which is computed from Barometer:raw, was increasing. This seems to be an error. This can also be seen with relativeHeight which is then computed from Barometer:smooth. Note, that vpsHeight also shows the AC descending. Not shown are the motorCommanded data which are decreasing.
That's what happened. It's a mystery, to me at least, why Barometer:smooth started to increase. It should be just a simple smoothing algorithm applied to Barometer:raw to smooth it and make it acceptable for the purposes of maintaining altitude. I note that you're using firmware 01.03.0700. Maybe, we'll start seeing more of these.

Thank you!  One note though, the day of that crash I was on .600 firmware. I didnt update to .700 until the following day (release day was the 9th) and haven't had any issues.  Do you think because this is a computation/firmware issue that it warrants sending the AC back? Or hope a FW...maybe .700...corrected this? I just got this one back as a warranty replacement and that was a month turnaround! Plus, I have the goggles coming!

Reznor99 Posted at 2017-5-12 16:18
Thank you!  One note though, the day of that crash I was on .600 firmware. I didnt update to .700 until the following day (release day was the 9th) and haven't had any issues.  Do you think because this is a computation/firmware issue that it warrants sending the AC back? Or hope a FW...maybe .700...corrected this? I just got this one back as a warranty replacement and that was a month turnaround! Plus, Ii have the goggles coming!

So we know it's nothing to do with .700 ..

geofox784 Posted at 2017-5-12 16:10
Any reason you were discharging the battery to 30%?

I am taking a short trip soon. I have been reading here and on other forums to discharge the batteries for carry on luggage. Just to be safe before boarding plane....

Reznor99 Posted at 2017-5-12 16:18
Thank you!  One note though, the day of that crash I was on .600 firmware. I didnt update to .700 until the following day (release day was the 9th) and haven't had any issues.  Do you think because this is a computation/firmware issue that it warrants sending the AC back? Or hope a FW...maybe .700...corrected this? I just got this one back as a warranty replacement and that was a month turnaround! Plus, I have the goggles coming!

Sorry, my mistake about the firmware version. That's actually a bug in CsvView/DatCon that I thought was fixed. I didn't think it was firmware related; I just threw that out as a possibility.
I don't have a specific suggestion. Except to say don't fly horizontally that close to the ground. If it we're my Mavic I would try to make it happen again but at 3 meters. But, you may have a different perspective. At 3 meters vpsHeight still works making it possible to see if the problem still exists.

It's pretty clear that Baro:Smooth is a smoothed version of Baro:Raw. Take a look at this post from MavicPilots
http://mavicpilots.com/threads/maximum-attitude-hack.12355/page-3#post-146542
But, the algorithm that computes Baro:Smooth may have some other inputs besides Baro:Raw. Perhaps a DJI engineer could answer that question.

BudWalker Posted at 2017-5-13 03:05
Sorry, my mistake about the firmware version. That's actually a bug in CsvView/DatCon that I thought was fixed. I didn't think it was firmware related; I just threw that out as a possibility.
I don't have a specific suggestion. Except to say don't fly horizontally that close to the ground. If it we're my Mavic I would try to make it happen again but at 3 meters. But, you may have a different perspective. At 3 meters vpsHeight still works making it possible to see if the problem still exists.

Understand.  I will try to replicate the problem this afternoon.  I flew again yesterday with no noticeable issues but i didnt look at the logs. I also sent an email off to support.  Unless I get word from DJI that I need to send it in for repair I will continue flying cautiously until I feel I can trust this thing again and assume this was the result of bad conditions/my error or a FW problem that will be fixed. Or a fluke...

Reznor99 Posted at 2017-5-12 07:55
Had a hard time finding the right log.  I think this is it though.  Thanks for the help!

https://www.dropbox.com/s/bwbfihues0z9gk5/FLY021.DAT?dl=0

Sorry for the crash. I have forwarded your flight data to our engineers for review.
If we get any update, we will let you know.

DJI Mindy Posted at 2017-5-14 02:45
Sorry for the crash. I have forwarded your flight data to our engineers for review.
If we get any update, we will let you know.

Thank you.

DJI Mindy Posted at 2017-5-14 02:45
Sorry for the crash. I have forwarded your flight data to our engineers for review.
If we get any update, we will let you know.

Yes Mindy, let me know what they find because I just got this response from DJI:

"Dear Michael,

Thank you for contacting DJI.

We are very sorry to hear about the problem you are having with your DJI product. We recommend to send your unit back in our facility for better diagnosis and repair..."

Did they even look at my logs I wonder? I just got this Mavic back from a warranty repair. It took a month to get it back too. I would rather not go through that downtime again if this a FW fix.

Reznor99 Posted at 2017-5-14 03:32
Yes Mindy, let me know what they find because I just got this response from DJI:

"Dear Michael,

Since you have crashed the drone, our support team cannot locate the issue remotely. They recommend you to send it in. And after received your drone, our engineers will help to analyse the flight data inside the drone.
Since you have provided the flight data, I have forwarded your data to our engineers directly.
Our engineers will let you know what went wrong and if you need to send it in for further evaluation.

DJI Mindy Posted at 2017-5-14 20:06
Since you have crashed the drone, our support team cannot locate the issue remotely. They recommend you to send it in. And after received your drone, our engineers will help to analyse the flight data inside the drone.
Since you have provided the flight data, I have forwarded your data to our engineers directly.
Our engineers will let you know what went wrong and if you need to send it in for further evaluation.

Great. Thanks.  I will just wait to hear from them.  I am travelling for a few days and will have my Mavic.  I will continue to fly cautiously.  

I did test fly in the same location as the crash and with the same conditions - weather and wind were about the same.  I flew aggressively all over my back yard (short runs) and the gusting from the wind did push the drone down several times such that I had to bring it back to a safe height before I could continue.  If the drone had been farther away and I didn't have that close perspective it would have ended up crashing into the ground.  But...I think that this was due to the bad conditions/low altitude/wind and the AC responded acceptably.  No sudden dives into the ground really.

I also flew at 200 ft (with nothing below but a field) over the weekend and the Mavic didn't have any issues that I noticed.  I would be willing to accept that my crash was just the result of crappy conditions, close to ground, wind eddying and messing with barometer, etc. but I would love to get that confirmed.  Still a little nervous...

Reznor99 Posted at 2017-5-15 06:00
Great. Thanks.  I will just wait to hear from them.  I am travelling for a few days and will have my Mavic.  I will continue to fly cautiously.  

I did test fly in the same location as the crash and with the same conditions - weather and wind were about the same.  I flew aggressively all over my back yard (short runs) and the gusting from the wind did push the drone down several times such that I had to bring it back to a safe height before I could continue.  If the drone had been farther away and I didn't have that close perspective it would have ended up crashing into the ground.  But...I think that this was due to the bad conditions/low altitude/wind and the AC responded acceptably.  No sudden dives into the ground really.

Could you please link your mobile to the computer , find the flight log by this path:   ...\DJI\dji.go.v4\Flightlog
And what your current DJI GO version? Did you push the throttle full down before the Mavic drop?

DJI Mindy Posted at 2017-5-16 01:58
Could you please link your mobile to the computer , find the flight log by this path:   ...\DJI\dji.go.v4\Flightlog
And what your current DJI GO version? Did you push the throttle full down before the Mavic drop?

Here you go:  https://www.dropbox.com/s/8qj7iq ... 8_03-17-43-066?dl=0

I hope that's the right log.  I am using DJI Go 4.0.7.  Just looking at my stick movements in the app I don't think I throttled down until after it was on ground.  At that moment though I can't remember it happened so fast.  I did however throttle forward before crash at 66-68%.  I thought maybe the extreme angle of pitch as I throttled forward made the VPS think I was ascending or higher off the ground than I was in actuality?  Flew again last night over grassy ball field at different altitudes and the Mavic handled ok.  

Thanks again Mindy.  Keep me informed.

DroneFlying Posted at 2017-5-12 06:57
Assuming that it wasn't responding to your stick commands the behavior in the video certainly seems odd but also somehow vaguely familiar. My first thought was that something might have triggered the forward sensors, but there's nothing obvious in the video to explain it and your best bet is probably to upload the flight's DAT file to DropBox and post a link to it here.

Has anybody had trouble flying into thermals. My Mavic got taken up to 106mtrs without touching any sticks. it was scary

fans28300a9f Posted at 2017-5-16 05:31
Has anybody had trouble flying into thermals. My Mavic got taken up to 106mtrs without touching any sticks. it was scary

I suppose it's possible but I hadn't heard of that. Can you post the log from that flight on PhantomHelp?

Reznor99 Posted at 2017-5-16 05:17
Here you go:  https://www.dropbox.com/s/8qj7iqzzwo7ivw0/FLY021.DAT%4017-05-08_03-17-43-066?dl=0

I hope that's the right log.  I am using DJI Go 4.0.7.  Just looking at my stick movements in the app I don't think I throttled down until after it was on ground.  At that moment though I can't remember it happened so fast.  I did however throttle forward before crash at 66-68%.  I thought maybe the extreme angle of pitch as I throttled forward made the VPS think I was ascending or higher off the ground than I was in actuality?  Flew again last night over grassy ball field at different altitudes and the Mavic handled ok.  

Thank you. If we get any update, will let you know as soon as possible.

BudWalker Posted at 2017-5-12 15:18
I looked at this flight. In summary, the problem seems to be that the Mavic thought it was gaining altitude, but, it actually wasn't. In response it "corrected" for the percieved gain by losing altitude. At time 398 Barometer:raw was decreasing but Barometer:smooth, which is computed from Barometer:raw, was increasing. This seems to be an error. This can also be seen with relativeHeight which is then computed from Barometer:smooth. Note, that vpsHeight also shows the AC descending. Not shown are the motorCommanded data which are decreasing.
That's what happened. It's a mystery, to me at least, why Barometer:smooth started to increase. It should be just a simple smoothing algorithm applied to Barometer:raw to smooth it and make it acceptable for the purposes of maintaining altitude. I note that you're using firmware 01.03.0700. Maybe, we'll start seeing more of these.

Looks like someone misplaced a (+/-) sign in the smoothing algorithm.  Although that doesn't explain why the raw baro was decreasing.  How sensitive are the barometers to cross-winds, i.e. Bernoulli effect.  Surely they're well isolated.

Griffith Posted at 2017-5-17 11:44
Looks like someone misplaced a (+/-) sign in the smoothing algorithm.  Although that doesn't explain why the raw baro was decreasing.  How sensitive are the barometers to cross-winds, i.e. Bernoulli effect.  Surely they're well isolated.

It happened to me again (dip, let off sticks, no crash) in back parking lot of my office building.  Wind was swirling and I was pushing straight forward and straight backward at full stick about 3 ft off the ground.  Wind to me seems to have some part in this behavior.  I don't really see these issues at higher altitudes either.

You ain't the only one, I got sudden drops too!

You ain't the only one, I got sudden drops too!  

bochen7 Posted at 2017-5-17 12:30
You ain't the only one, I got sudden drops too!  https://www.youtube.com/watch?v=S_ULFmUga_M

Hmmm.  Does that happen outside with full signal, gps etc, as well?  This looks like a different issue than mine, but I would guess the smart people here are going to need to see your logs to make a diagnosis.

Reznor99 Posted at 2017-5-17 12:39
Hmmm.  Does that happen outside with full signal, gps etc, as well?  This looks like a different issue than mine, but I would guess the smart people here are going to need to see your logs to make a diagnosis.

So when I takeoff I immediately throttle down and it is what happens every time...


/////////

Mavic landing issues after upgrading to firmware 400 from 200
1. Noticed that when testing, I did a takeoff and when it hovers about a feet off the ground, I try to land again. But instead of landing slowly or "pausing a few seconds" at the landing threshold before then commencing its landing, it immediately descends at a rate as if there was nothing underneath it at all, hitting the ground at a fast pace and then bouncing off it and back to the ground and some series of micro-bounces before it finally stops.

Previously, before upgrading to 400 and while on 200, whenever I first liftoff, there is no such thing as lifting off only a few inches from the ground, the Mavic has a mind of its own and does an autotakeoff sequence lifting it at the 3 feet or so "threshold" height.. so even if I immediately demand it to land a moment after takeoff, it will still hover at the 3 feet "threshold" height, and then if I'm still holding down the decrease throttle button, it will commence its landing sequence which at that point the Mavic takes over full control again and comes to a soft smooth landing.Meaning, right after takeoff, it previously ascended to the three feet or so of "landing threshold" no matter what my inputs where, and then ONCE at the threshold, if it detected that I still wanted to land, it would pause there for a few seconds, then commence a landing.... NOT anymore, on the new firmware, if I tell it to land immediately after takeoff, before it can reach the three feet of altitude of the landing threshold, it will not do its "pause", it will not climb to the 3 feet of landing threshold, instead it just descents at a fast pace, hitting the ground as if there was nothing underneath it at all.

2. So I thought wow, okay let me test it normally, so I start from takeoff again, already in GPS mode, and launch this time to a height of 10 feet, hover around and then attempt to land. This time the Mavic descends down to its 3 feet or so of "landing threshold" altitude where it pauses for a few seconds (as it always does, even in 200 firmware) but what happens next is strange, instead of a consistent smooth and slow descent resulting in a gentle landing, it descends MUCH faster, and although it didn't bounce up in the air this time, no doubt it was a very hard landing.... I've landed enough times to know the rate of descent and what a normal landing looks like... it seems for whatever reason after the update to 400 firmware there is a glitch and sometimes it lands very hard, after it already passed and paused at the 3 feet landing threshold.....

Yea, be sure to properly​ calibrate your Mavic Pro especially after that experience.

Recheck all your settings after update.  Some may revert to a default setting.

DJI Mindy Posted at 2017-5-16 20:15
Thank you. If we get any update, will let you know as soon as possible.

Anything Mindy?  I did have one more sudden dip when I was flying close to ground.  I was making some aggressive movements forward/backward to force the behavior and it was windy, etc, but I have also been doing some smooth, controlled flying at different heights with no weird behavior at all.  Goggles come tomorrow and if I need to send this Mavic in for replacement I would like to do it sooner rather than later.

Flying height of about 0.5m, continue to pull down the throttle, triggering forced landing

wisnia.sebastia Posted at 2017-5-23 01:18
Flying height of about 0.5m, continue to pull down the throttle, triggering forced landing

What?  I didn't pull down throttle until MP was on the ground.  At least I don't think I did.  Are you a DJI employee?  If this is an official response from DJI I will believe it was my error, but not until I know for sure.