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Unbelievable flaw leds to epic crash
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2227 47 2017-3-20 12:17:38
fans453b768c
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I made a video to explain what happened.



Any hints how to avoid such situations in the future? These Birds are a little to expensive to buy them in bulk.

tobias
2017-3-20 12:17:38
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fans90d4f438
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sorry it happened. But you put together a NICE video that's for sure
2017-3-20 12:32:32
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tokenbrit
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Sorry to hear about the crash.  The avoidance system is a great idea in concept, but it's not perfect and at best you can only hope it will save you from an accident if you make an error.

Mine flew into a sign in "follow-me" mode - fortunately I got away with only some broken props. It was however my first crash in nearly 2 years and happened because I relied on the system and wasn't paying enough attention.
2017-3-20 12:50:13
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mmee
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Have you ever calibrated the obstacle avoidance system? There is a calibration procedure.
2017-3-20 13:10:53
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Scunna
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Keep away from buildings.
2017-3-20 13:18:34
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NoSale
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Sorry for the damage you incurred, but glad you got everything back.

And I do appreciate the detailed, well put together video explaining the circumstances, and response from DJI.

I assume nothing will work as advertised.  But I do fly with more peace of mind believing that there might be some safe guards to oversights on my part.  Regardless, I try to fly conservatively and with caution at all times.

Again, thanks for the informative video.  Hope your future flying is without incident.......
2017-3-20 13:26:00
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hallmark007
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Do you have flight logs you can upload to http://www.phantomhelp.com/Phantom-4/#DataLog, and some here might be able to throw some light as to what might have happened.
2017-3-20 13:37:07
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Poop Chute
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Nice video.  Glad you recovered the bird, albeit somewhat battered & bruised.  Out of curiosity  did you have the RTH altitude set higher than the buildings?  I fly over Baltimore often & always set my RTH for 215m (705') "just in case" as that clears everything in the downtown corridor.
2017-3-20 13:37:33
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Danny-B-
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Logs?
You sure the home point was set at you? It looks like it was on an RTH path and height was set too low.

Just upload your logs to phantomhelp or healthydrones
2017-3-20 13:38:51
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RightStuffed
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Excellent!
2017-3-20 13:59:32
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Daroga
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tobias,

Sorry for your experience! That's a real bummer video but also very well produced, Thanks!

The major flaw with this crash appears to be impromptu flying. That's flying without any prior planning. There are two groups of impromptu flyers - those that have crashed and those that will crash.... The greatest flaw for remote pilots is depth perception both in visual line of sight and beyond visual range. At almost any distance, it's difficult to always know if you are in front of or behind an obstacle when flying, climbing or decending. Without minimal prior planning, you're flipping the coin with each flight -> crash or dumb luck....
   
Now I'm not trying to take any fun away from flying. It's just that aviation comes with risks and it's important for all of us to perform some risk assessment to configure our aircraft, the GO4 App, and to then fly to minimize these risks.
   
Had you planned to fly aroud that building, you could have looked at Google Earth to see that it appears to be about 125m tall. The futher building is about 30m taller. So you could have been prepared to set your RTH for 150-160m. What was your RTH?
   
DJI and government aviation agencies recommend remaining in visual line of sight, but more important is our antenna line of sight. Fly behind a hill, a building, a tower, etc and you will loose your connection. Only some of our IOC functions like POC or waypoints allow you to plan a mission and have the aircraft execute that mission even when antenna line of sight may be lost. But even then, you  must set an appropriate RTH height.
   
So in the future, at least minimally plan your flights, double check your RTH and vision system settings, and know when and where you might loose your antenna line of sight. You can use use obstacle avoidance to back you up, but don't expect it to always bail you out of your pilot respnsibilities as it can be fooled....
   
As others have noted, the aircraft flight logs will show your settings and the details of the flight.

2017-3-20 14:07:15
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DroneFlying
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"You don't fly near buildings. The manual says so."

Maybe so, but "near" is a little vague and in its broadest interpretation could probably be applied to almost all flights. In any case, it'll be interesting to see what the logs show.
2017-3-20 14:30:50
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fans453b768c
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mmee Posted at 2017-3-20 13:10
Have you ever calibrated the obstacle avoidance system? There is a calibration procedure.

No, i never did. Didn't know that this is possible or necessary.
2017-3-20 15:19:50
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fans453b768c
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Poop Chute Posted at 2017-3-20 13:37
Nice video.  Glad you recovered the bird, albeit somewhat battered & bruised.  Out of curiosity  did you have the RTH altitude set higher than the buildings?  I fly over Baltimore often & always set my RTH for 215m (705') "just in case" as that clears everything in the downtown corridor.

Yes i did set RTH altitude at 200m here
2017-3-20 15:20:24
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fans453b768c
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Daroga Posted at 2017-3-20 14:07
tobias,

Sorry for your experience! That's a real bummer video but also very well produced, Thanks!

Thanks for your helpful advise around planning. While i certainly was out of antenna-line-of-sight during this flight - i was not when the incident occurred.
2017-3-20 15:22:05
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geofox784
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Sync your records to healthydrones.com and you should get a ton of interesting data.

Download the HD sync app https://healthydrones.com/sync-app

Sync your records to the DJI cloud then follow the instructions in the HD sync app.

2017-3-20 16:17:00
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Ex Machina
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Nicely put together video about your experience, though I'm sorry you had to make it. Were you flying in Sports mode? OA doesn't work in that mode, fwiw.

Agree with the others, logs should give you clues about why this happened.
2017-3-20 19:20:56
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geofox784
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I reconstructed the crash in google earth assuming that this was a RTH sequence.

Based on your video, google earth shows the altitude of your takeoff location to be 160ft.

It appears that it collided the building almost perfectly in line with height of the stairwell structure on the west side of the building. Placing my cursor at that estimated location of impact based on the trajectory just before video loss it shows an altitude of 370ft on the building. 370' - 160' = 210' AGL or 64m AGL.

Conclusion:
The height of the RTH must have been set to ~64m AGL OR LESS. I believe it was less because the AC did not raise altitude when the RTH sequence started. It simply stayed at its current height. This happens when the AC is already higher than the selected RTH altitude. Did you update the firmware recently? The latest update caused the RTH the go back to the default 30 meters.  The highest point of that building is 244' AGL or ~74m.

USER ERROR IF RTH SEQUENCE. - User should have checked RTH altitude before flight and set it to at least 100m.
Front obstacle avoidance was also most likely disabled. It should have easily detected and prevented the impact. Regardless, obstacle avoidance should NOT be used as a substitute for a good RTH altitude.

I also think that the home point shown in the video is not accurate as the AC did not head in that direction and the AC had LOS to the home point at that location.

The logs will help prove or disprove this. Upload them to healthy drones. If they dont show any information after disconnect then send the logs from the AC itself instead of the remote to DJI engineering. They can see what happens after disconnect.


SCREENSHOT FROM VIDEO:


SCREENSHOT FROM GOOGLE EARTH:


2017-3-20 21:03:15
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mmee
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geofox784 Posted at 2017-3-20 21:03
I reconstructed the crash in google earth.

Based on your video, google earth shows the altitude of your takeoff location to be 160ft.

Problem with that is the building that he hit is the opposite direction from the Home point.
2017-3-20 21:19:43
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Jason Lane
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geofox784 Posted at 2017-3-20 21:03
I reconstructed the crash in google earth.

Based on your video, google earth shows the altitude of your takeoff location to be 160ft.

No offense, but your conclusion relies entirely on a lot of assumptions. You're basically saying that the OP was wrong or lying about the facts.

- "The height of the RTH must have been set to ~64m AGL OR LESS." He said his RTH height was set to 200m.
- "Front obstacle avoidance was also most likely disabled." Well, the OP seems to believe they were enabled.
- You "think that the home point shown in the video is not accurate."  That's a big assumption, with nothing to back it up at this point.

I agree that if everything you've assumed is true, that would explain the crash. But bottom line, it's not fair to make any of those assumptions without the data. It's fair enough to ask those questions, but you can't say that you've come to a "conclusion" without seeing the flight data first.
2017-3-21 00:07:33
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DJI Mindy
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Did you sent it in for further diagnosis?
Our engineers will help to analyse the flight data inside the aircraft and let you know what could have caused the issue.
2017-3-21 02:41:29
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hallmark007
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Think it's a bit early to make the assumption it was a unbelievable flaw, it may have been but it would help here if you posted logs.
2017-3-21 04:30:32
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geofox784
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Jason Lane Posted at 2017-3-21 00:07
No offense, but your conclusion relies entirely on a lot of assumptions. You're basically saying that the OP was wrong or lying about the facts.

- "The height of the RTH must have been set to ~64m AGL OR LESS." He said his RTH height was set to 200m.

"The logs will help prove or disprove this. Upload them to healthy drones."

Its entirely possible I am wrong. This could all just be a fly away for no reason in a random direction. However if it is a RTH sequence then it was not setup correctly. Need the logs to figure this out.
Also OP thinks that it was set to 200m but its an easy mistake to have it been otherwise. There has been a few other cases of users forgetting the check the RTH altitude setting after firmware updates.
2017-3-21 05:11:44
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geofox784
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Jason Lane Posted at 2017-3-21 00:07
No offense, but your conclusion relies entirely on a lot of assumptions. You're basically saying that the OP was wrong or lying about the facts.

- "The height of the RTH must have been set to ~64m AGL OR LESS." He said his RTH height was set to 200m.

Made some edits to my wording.
2017-3-21 05:19:39
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CuaC
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I'd love to see the healthydrones log file on this crash.
2017-3-21 05:21:37
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SkunkWerxs
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2017-3-21 05:29:46
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geofox784
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Here is a guide of how to sync the log. Shouldn't take more than 5 min. https://healthydrones.com/sync-app-ios?instr=1
2017-3-21 06:30:10
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jeebs-9
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Was the drone in sports mode?
2017-3-21 06:44:31
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hallmark007
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I have a feeling more and more of these videos are just click bait.
2017-3-21 09:49:36
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fans453b768c
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Ex Machina Posted at 2017-3-20 19:20
Nicely put together video about your experience, though I'm sorry you had to make it. Were you flying in Sports mode? OA doesn't work in that mode, fwiw.

Agree with the others, logs should give you clues about why this happened.

I was not on sport mode, thanks for the kind words.
2017-3-23 23:01:01
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fans453b768c
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DJI Mindy Posted at 2017-3-21 02:41
Did you sent it in for further diagnosis?
Our engineers will help to analyse the flight data inside the aircraft and let you know what could have caused the issue.

About to discuss that right now.
2017-3-23 23:02:14
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fans453b768c
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hallmark007 Posted at 2017-3-21 09:49
I have a feeling more and more of these videos are just click bait.

What? Please explain. You are accusing me of crashing my 1,2k drone into a building to - get clicks on youtube?
2017-3-23 23:12:59
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hallmark007
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fans453b768c Posted at 2017-3-23 23:12
What? Please explain. You are accusing me of crashing my 1,2k drone into a building to - get clicks on youtube?

No im not accusing you of crashing your AC for clicks on you tube, but you made a big headline about a big flaw in the Mavic , and it was an opportunity to help others if you would have posted logs to show what the flaw might have been, and in turn get help from the community here.

You had been asked by several to post logs, this would help clear up speculation as to what might have happened, you seemed not to take people up on their offer.

So where you just here to show your video or where you here to get help from others. When you announce there is a big flaw in the Mavic then other owners would appreciate finding out what this flaw is. It's your choice it's your aircraft.
2017-3-24 00:40:42
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DroneFlying
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fans453b768c Posted at 2017-3-23 23:12
What? Please explain. You are accusing me of crashing my 1,2k drone into a building to - get clicks on youtube?

Well, it is a fact that you did the following:

  • Posted a video that seemed to be intended to elicit sympathy, implying that the crash wasn't your fault and that you were denied a (free) warranty repair by DJI.
  • Asked for, "any hints how to avoid such situations in the future".

The problem is that without the flight log information nobody here can offer much sympathy or meaningful advice beyond "don't fly near buildings", which is essentially what you said you were already told by DJI. And yes, I find it a little strange that even after several days and multiple requests you still haven't provided the logs, especially considering that doing so would require only a fraction of the time it must have taken you to create that slick video.

Historically, most I-crashed-but-it-wasn't-my-fault claims on this forum turn out to be pilot error, and without the logs most of us are going to go with the odds and assume that yours is just another example of that.


2017-3-24 04:06:17
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Impact9
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From my understanding you are not suppose to fly the mavic indoors, around bodies of water larger than a tea cup, near trees, grass, tall shrubs, bumps in the road, buildings, dog houses, people of any size, in outdoor environments that exceed 400ft in altitude, nor while temps are below the freezing point of lead as it may cause your drone to fall from the sky. You must monitor solar radiation as it may possibly make batteries suddenly error out causing the drone to be taken over by 3rd party microwave ovens that are not in use at ground level.  If you stood were someone else has stood in the last 2000 years as it could cause interference as well.

Yes I will bitch, My drone flew away and crashed and it wasn't my fault. DJI has had it for 2 weeks now and still have yet to provide any insight or update my repairs status.
2017-3-24 10:55:50
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SkunkWerxs
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2017-3-24 16:55:00
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2017-3-24 16:55:30
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Impact9
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SkunkWerxs Posted at 2017-3-24 16:55
Impact9,

Your too quick to claim a FLYAWAY in your post and supporting a person that refuses to provide a copy of the Flight Log !!! I understand DJI has obtained your Flight Log That you provided to them and DJI has found out That your so called FLYAWAY was PILOT ERROR!!!!!!!!!!

What I found is many of the so called "experts" are quick to throw pilot error out there on post that don't have a concrete backing of the flight log. Then if the OP don't understand how to get a flight log uploaded, this group of people takes credit away from the OP's account of what happen. Thus, it must be pilot error if no flight log is shared with the world. So Expert, explain to me why my drone went left and up uncommanded (that IS a flyaway) had it not done this my throttle commands wouldn't even be mentioned because it wouldn't have crashed. Period.
2017-3-25 05:09:58
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DroneFlying
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Impact9 Posted at 2017-3-25 05:09
What I found is many of the so called "experts" are quick to throw pilot error out there on post that don't have a concrete backing of the flight log. Then if the OP don't understand how to get a flight log uploaded, this group of people takes credit away from the OP's account of what happen. Thus, it must be pilot error if no flight log is shared with the world. So Expert, explain to me why my drone went left and up uncommanded (that IS a flyaway) had it not done this my throttle commands wouldn't even be mentioned because it wouldn't have crashed. Period.

What I found is many of the so called "experts" are quick to throw pilot error out there on post that don't have a concrete backing of the flight log.

Maybe this comment wasn't directed at me, but for the record I've never thought of or referred to myself as an "expert". I do have opinions, though, and yes I feel as free to share mine here just as you do.

Then if the OP don't understand how to get a flight log uploaded, this group of people takes credit away from the OP's account of what happen.

So your theory is that the OP is smart enough to make that video but it takes him 5+ days to figure out how to accomplish something (uploading flight logs) countless others have done with ease? Interesting.
2017-3-25 05:26:20
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SkunkWerxs
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2017-3-25 06:10:04
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