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Mavic Destroyed - How can I get my log analyzed?

cardplayer71

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Hello,

I just took my Mavic on a dream trip, during which it was destroyed on day 2. Basically, I wanted to use Course Lock mode for a fairly simple shot along an ocean shoreline. The flight path was to go between a sea cliff and a rock outcropping in the sea, and to yaw the craft as it panned past the rock formation, to film the rocks from an interesting perspective. There was plenty of space there, probably in excess of 100 feet of gap.

At some point near the rocks, the Mavic lost connection. I moved closer to it, and closer to the water, in order to help regain the connectivity. Luckily, the connectivity was regained, and the flight log was transmitted, along with the real-time video of its destruction. During the disconnected period, the flight logs on my phone seem to indicate that the Mavic lurched about 100 feet toward the shore, thus putting it behind the cliff, and this was not initiated by my actions. The Mavic then initiated Go Home mode, and proceeded to fly directly toward the cliff face, as that cliff was now between me and the copter.

As I regained the visual feed, I could see the Mavic heading toward the cliff face at what appeared to be top speed (22mph or so). I made an attempt to abort the RTH via control inputs. For a brief moment, the Mavic stopped some distance from the cliff face. Notably, I applied full rearward pitch in an attempt to not crash into the cliff. Rather than fly in reverse, the Mavic accelerated and flew straight into the cliff as if it was still in Course Lock mode, despite being in Go Home mode. I am not certain if it simply ignored me, or if there is a bug where RTH does not cancel Course Lock, and the pitch commands are still applied along the original heading. Either way, it basically mashed the accelerator and destroyed itself.

Any ideas how to get this flight log analyzed? I was fortunate enough that it transmitted the flight log in the seconds before impact, and I was able to recover the wrecked craft. The flight log and its replay seem to indicate that the Mavic simply malfunctioned.
 
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Mavicsailor

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Hello,

I just took my Mavic on a dream trip, during which it apparently malfunctioned and destroyed itself on day 2. Basically, I wanted to use Course Lock mode for a fairly simple shot along an ocean shoreline. The flight path was to go between a sea cliff and a rock outcropping in the sea, and to yaw the craft as it panned past the rock formation, to film the rocks from an interesting perspective. There was plenty of space there, probably in excess of 100 feet of gap.

At some point near the rocks, the Mavic lost connection. I moved closer to it, and closer to the water, in order to help regain the connectivity. Luckily, the connectivity was regained, and the flight log was transmitted, along with the real-time video of its destruction. During the disconnected period, the Mavic lurched about 100 feet toward the shore, thus putting it behind the cliff, and this was not initiated by my actions. The Mavic then initiated Go Home mode, and proceeded to fly directly toward the cliff face, as that cliff was now between me and the copter.

As I regained the visual feed, I could see the Mavic heading toward the cliff face at what appeared to be top speed (22mph or so). I made an attempt to abort the RTH via control inputs. For a brief moment, the Mavic stopped some distance from the cliff face. Notably, I applied full rearward pitch in an attempt to not crash into the cliff. Rather than fly in reverse, the Mavic accelerated and flew straight into the cliff as if it was still in Course Lock mode, despite being in Go Home mode. I am not certain if it simply ignored me, or if there is a bug where RTH does not cancel Course Lock, and the pitch commands are still applied along the original heading. Either way, it basically mashed the accelerator and destroyed itself.

Any ideas how to get this flight log analyzed? I was fortunate enough that it transmitted the flight log in the seconds before impact, and I was able to recover the wrecked craft. The flight log and its replay seem to indicate that the Mavic simply malfunctioned.
Best to download the DAT file from the Mavic using DJI assist to this thread using Dropbox or similar. This will give the most detailed information. Also post the transmitted log using healthy drones. Sorry to hear about your crash.
 

cardplayer71

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If the Mavic still can be switched on, yes.
But PhantomHelp gives much more detailed infos than HealthyDrone.

It can still be switched on, but it gets very hot on the bottom almost immediately. Can you point me to the process for getting this DAT file via DJI Assist? Is it straightforward, and something I can do quickly before it gets too hot? (I wish DJI would log to the SD card also!)
 
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Mavicsailor

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It can still be switched on, but it gets very hot on the bottom almost immediately. Can you point me to the process for getting this DAT file via DJI Assist? Is it straightforward, and something I can do quickly before it gets too hot? (I wish DJI would log to the SD card also!)
It does take a few minutes to download the dat file from the Mavic, so maybe put a fan on it to keep it cool. Maybe the internal fan is not working? You should be able to hear it once it starts. It gets pretty warm before it turns on, then cools considerably thereafter.

Anyhow, go to the DJI support site and download DJI Assist 2 to your computer. Attach the same cable used to charge the RC to the computer and Mavic. Boot the software. Turn on the Mavic. You will see an image of a USB connecting. Click on flight data. Go into my computer and you will see the Mavic memory with all of your DAT flight records. Download the problem flight file. Post to Dropbox
 

DodgeP

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Is it possible that you lost orientation and actually piloted the Mavic into the clliff face? I don't know your experience level right .... so what happens when you lose connection using the DJIGo app it initiates RTH right? The unfortunate part is, you crashed. The unfortunate part is IFM's instill too much confidence and often lead to mistakes. Hopefully you picked up DJI Care.
 

Peio64270

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You have to rely the Mavic to your computer via USB with DJI Assistant 2 already runing. Switch on the Mavic. If everything goes well, DJI-Assistant 2 should recognize your drone. Clic on it and then enter the data viewer. Save the last .txt file in your computer. It takes one or two minutes.
 
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james_mav

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If it was in RTH then the first thing the bird should have do
Is it possible that you lost orientation and actually piloted the Mavic into the clliff face? I don't know your experience level right .... so what happens when you lose connection using the DJIGo app it initiates RTH right? The unfortunate part is, you crashed. The unfortunate part is IFM's instill too much confidence and often lead to mistakes. Hopefully you picked up DJI Care.

I tend to agree that something doesn't make sense. The Mavic should have gone up if it was in RTH mode instead of slamming straight into the rocks. What about the forward sensors? I tend to think some panic decisions contributed to the crash.
 

Cyberpower678

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Something sounds off here. This story seems to have me believe pilot error occurred somewhere. I'll hold off on judgement until I can see the flight logs.
 
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cardplayer71

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Thank you for your help and interest! The good thing here is that we also have the crash video to examine along with the logs. So, while it was disconnected, there should have been no movements on the part of the aircraft other than to initiate an RTH. That is my understanding of how it works. However, once I got video back, and this can be seen by comparing my stick inputs from the telemetry, it looks like the aircraft moved laterally of its own accord. So, instead of following the heading it was on per RTH, it moved off course about 100 feet in a perpendicular manner to the original heading. The interesting thing is that the telemetry never shows any roll inputs from me, but the copter moved anyway. Then you can see, along with the video, that I did attempt a last ditch effort to apply reverse pitch to not hit the cliff. However, the copter accelerated toward the cliff and was subsequently destroyed. I'll be the first person to own an operator error if we find one. I just want to know what happened, specifically why it moved 100 feet or so off course, laterally, perpendicular to the line of flight, with zero roll input.
 
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cardplayer71

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Also, I should point out that the copter appears to stop right before the cliff face, ostensibly due to obstacle avoidance. It is at this time that I applied reverse pitch, feeling that it was a.) connected b.) stopped, c.) under control, and that d.) I could now pilot it out of the situation. Being facing the cliff, at an indeterminate distance, I applied reverse pitch at 100% to reverse away from the cliff and obtain a wider angle of view. Unfortunately, the copter did not go in reverse. Rather, it accelerated forward and wrecked into the cliff. This all happend in about 3 seconds, so let's see what the logs show!
 

Kilrah

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Well it sounds like operator error #1 is incorrectly setting RTH height.
Did you at any time exit course lock mode? I would think it doesn't exit automatically, so once you regain control after a loss of signal it's still in the active IFM and the reason why your stick inputs were "weird".
 

cardplayer71

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Well it sounds like operator error #1 is incorrectly setting RTH height.
Did you at any time exit course lock mode? I would think it doesn't exit automatically, so once you regain control after a loss of signal it's still in the active IFM and the reason why your stick inputs were "weird".

Well, it was not supposed to go "around the corner", so RTH height is irrelevant here, because the cliff was so massive that it height would not have helped. Have you seen the cliffs on the Iceland coast?

Let's stop rushing judgement and work from the evidence. Posts like this add nothing of value to the discussion.

No, I did not cancel the IFM, and in fact the logs show that it was in "Go Home" and not "Course Lock" anymore, so why would it not have cancelled the mode when it flipped to RTH?
 

cardplayer71

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If it was in RTH then the first thing the bird should have do


I tend to agree that something doesn't make sense. The Mavic should have gone up if it was in RTH mode instead of slamming straight into the rocks. What about the forward sensors? I tend to think some panic decisions contributed to the crash.

It didn't slam into the rocks. So imagine the mountain on the left (AKA 'the cliffs') and the rocks out in the water on the right. For whatever reason, while it was disconnected, it went sideways to the trajectory, so that now the mountain is between me and the Mavic. It was this mountain that it flew into after entering RTH. There was no height the Mavic could do, within legal limits, that would have overcome this mountain. I will put the video onto YouTube so that it makes more sense for everyone. I could see it stop before this mountain face, and based on this, and being in RTH mode, I attempted to take control. The first thing to do was back away from the mountain. Unfortunately, and very counterintuitively, it behaved much like it was still in Course Lock mode, although the log shows "Go Home" / RTH. So, when I applied reverse pitch, it moved toward the operator, i.e. towards the cliff, behaving much like it was still in Course Lock, albeit 100 feet from its original course.

There was no panic, just some present confusion as to why the stick input was reversed, resulting in a cliff impact instead of reverse pitch.

:)
 

cardplayer71

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Best to download the DAT file from the Mavic using DJI assist to this thread using Dropbox or similar. This will give the most detailed information. Also post the transmitted log using healthy drones. Sorry to hear about your crash.

OK, I believe that this is the DAT file from the crash. It seems that the Mavic creates new logs every time I turn it on, not just for "flights". This is the one I believe represents the fatal flight.

Dropbox - FLY087.DAT

Please let me know. Thank you!!
 

cardplayer71

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I think I see why it turned to "Go Home" LOL. It was the home point from the beach.

I still don't understand why it moved laterally while disconnected, though, and especially not why it applied a reversal of the pitch instruction. So, chalk one up to not paying attention on the starting point. OK, that's fine and it makes sense.

What about this issue of it still behaving like it was in Course Lock, though, in terms of the reverse pitch moving the copter back towards the origin point, and not actually in reverse? Shouldn't RTH automatically kill whatever active mode the copter was in at the time RTH is initiated? Also, why mash into the cliff? What happened to its obstacle avoidance? That's a fairly large obstacle.
 
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Robbyg

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I have noticed that no one is eager to help people with these problems because when answers are given and the operators don't like the answer they start going after the messenger.

I spent a few minutes looking at the DAT file and I can tell you that from what I see the Mavic did nothing wrong. You took off with an RTH altitude set to 35M which is very low for what you were doing. The Mavic went around the cliff, it lost signal, it initiated an RTH heading exactly back to were it took off from. It went up to 35M and then I assume obstacle avoidance was off because it slammed into the side of the cliff. I could spend more time looking at it but most of the time people do not want to hear that it is pilot error.
 
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