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DJI Mavic Air - FLY AWAY!

AlexSym

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Hi everyone,

Until a few weeks ago, I was the lucky owner of a brand new DJI Mavic Air. But some days ago, I had the bad luck to live a FLY AWAY with my drone and was unable to find it back... which is a shame because I benefit from the DJI Care Refresh insurance.

I immediately contacted the DJI customer support to explain my issue and the technical failures of the drone. Below, you will find my first exchange of mails between DJI and myself. Of course, their first reply is that the incident was caused by an improper flight environment which is completely not correct (you will see my justification in the mails hereunder).

So I would like to have the opinion of professionals that are not working for DJI because I think that they are not completely honest and transparent with me.

On this Dropbox link, you will be able to find the logs of the 3 last flights of the drone (log 2 should be the last flight) : DJI Mavic Air logs - Symons

Some of you could give me their opinion based on the comments of DJI and the flight logs ?

Thanks a lot for you help and your good advices !

If you need any other information, do not hesitate to ask.

Kind regards,
Alexandre

Mail exchange with DJI :

1. My first mail :

"Hi, I bought a DJI Mavic Air from Media Markt Belgium: ordered on 03/03/2018 and received on 26/03/2018. On 30/03/2018 I subscribed to the DJI care refresh insurance via the official website DJI (Agreement No.: xxx). From this date, I started to use my drone and I did not notice any anomaly. I took my DJI Mavic Air with me for a trek on the island of La Gomera (Spain). During the 3rd flight on the island (13/04/2018), a major technical incident occurred. Indeed, after takeoff, several anomalies occurred and I decided to return the drone by pressing the button "Return to home". The drone did not react to this command and left in the opposite direction. Despite my various attempts to regain control of the drone, I did not succeed. According to my observations, the drone crashed on an inaccessible cliff. However, he reported a GPS position several kilometers from his take-off point, where I went the next day without being able to find him. I extracted the logs files of the last 3 flights of my drone, which you will be able to download to examine them in details at the following link: DJI Mavic Air logs - Symons I would like, as part of my insurance DJI care refresh, to obtain the replacement of my drone. I am well aware of the fact that I have not been able to recover the accident drone despite my efforts, but considering the nature of the technical failure and the place where it occurred I consider myself to be in the conditions of replacing my drone. Yours sincerely."

2. DJI answer :

"Dear Alexandre,

We are very sorry to hear about the unfortunate experience you have had with your DJI product. We will provide you with the best support possible.

Please follow the tutorial to sync your flight records to the DJI server. You can find the tutorial: HERE

The cloud icon at the end of the flight record indicates the flight record has been successfully uploaded. Once the sync is completed, please provide the following information to us so we can submit your report for data analysis:

- First and Last Name:
- Shipping Address:
- Phone number:
- Model of your aircraft:
- Serial Number of the remote controller:
- Email address associated with your DJI Account you used for your last flight:
- Date and time of the incident:
- Description what you did to try and regain control:
- Video Cached (Applicable if you are recording during the accident, please refer to the attachment and export it from your mobile device and upload to Google drive/Dropbox.)
- Proof of Purchase:

Note:
1. If you fail to sync your flight records to the server, please refer to the attachment and send us the flight records txt files on your mobile device. If it’s Mavic, please send us the RC log as well if the product is Mavic.
2. Flight records are important in judging the accident is pilot error or manufacturing error. If for some reasons, if you fail to provide enough information per requested, the warranty claim of the RTHF issue might be denied.
3. Flight records analysis would be accepted by DJI data analysis team only when the aircraft is within warranty period.
4. Once we confirmed that you have synced your flight records successfully, it will take 2 or 3 business days for us to finish the data analysis.

Thank you for choosing DJI.

Best Regards,
DJI Support"


3. My answer

"Hi,

I just uploaded the flight records to the DJI servers. Hereunder, you will find the requested information:

- First and Last Name: xx
- Shipping Address: xx
- Phone number: xx
- Date and time of the incident: Date 13/04/2018, Time 5.09 pm
- Description what you did to try and regain control: After takeoff, several anomalies occurred and I decided to return the drone by pressing the button "Return to home". The drone did not react to this command and left in the opposite direction. Despite my various attempts to regain control of the drone, I did not succeed. According to my observations, the drone crashed on an inaccessible cliff. However, he reported a GPS position several kilometers from his take-off point, where I went the next day without being able to find him.
- Proof of Purchase: See attachment.

On Dropbox, you will find the logs from the RC : DJI Mavic Air logs - Symons

Important reminder, I subscribed to the DJI Care Refresh for my drone (Agreement No.: xx).

Could you confirm me that the flight records were correctly uploaded and that you have all the information needed to handle my request?

Kind regards."

4. DJI answer

"Dear Customer,

Thanks for your patience.

For your claimed case CAS-1719134-L7D5D2, we have already finished the analysis, and the result is as follows:
1. The aircraft worked in OPTI mode after took off due to the weak GPS signal;
2. T=00:41, H=28.8 m, the aircraft switched to Atti mode;
3. T=01:14, H=-69 m, the aircraft crashed with obstacles and rolled over, then the flight record ended;
4. In Attitude mode, the aircraft could not hover in place, brake and avoid obstacle automatically.
According to the analysis, the incident was caused by improper flight environment. Please fly with caution.

We truly appreciate your support for DJI. If you could not recover the product and consider to purchase another aircraft, we can try to especially apply for a 15% off discount for Mavic Air(Arctic White)without charger and remote. If you would like to take the offer, please offer us the following info:
Shipping address:
Contact name:
Phone number:

Should you have more questions, please feel free to let me know.
Best Regards,
Lydia
DJI Tech Support

5. My last answer

"Good morning,

I received your last mail including your analysis of the accident of my drone DJI Mavic Air.

I have examined these analyses in detail. Please find below 3 points which prove that the accident of my drone is due to technical failures:

  • You indicate that at T = 00:41 the drone switched from OPTI mode to ATTI mode. According to the technical information, switching to ATTI mode occurs when the lighting conditions are bad. This was absolutely not the case as the flight took place at 5.09 pm so there was no reason to switch from OPTI mode to ATTI mode.
  • Your analysis indicates that at the time of the crash of my drone, the measured altitude was -69m which demonstrates that the drone was in a situation of major technical failure.
  • Your analysis does not explain at all why the drone, from a certain moment in this flight, no longer reacts to the commands and has gone in the opposite direction. This situation seems to be comparable with many cases of "Fly away" DJI Mavic Air that can be found on various forums:
https://mavicpilots.com/threads/mavic-air-fly-away.37558/
https://mavicpilots.com/threads/mavic-air-fly-away-what-gives.39521/
https://mavicpilots.com/threads/another-flyaway.37822/
Mavic Air flyaway!

Given all these elements, it seems clear to me that the crash of my drone is linked to a major technical failure. For this reason, I would like to benefit from DJI product warranty.

Thank you in advance for the attention you will give to my request."
 
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Did you just rename the log files? I can't load to AirData or Phantom Help log viewer.
So, you took off before you got good GPS lock. So it doesn't know where home is. I wonder if it was going to previous logged location. I guess when you search through this forum, you've come across a lot of this 'fly away' is caused by pilots not waiting for GPS lock, and didn't check compass calibration. i.e. pilot error.
I don't know how else to view your log files. Maybe someone else could.
 
@AlexSym, please upload your TXT flight log here and post a link back here,
 
Hi,

Thank you for your answers!

When I try to upload the TXT flight log on AirData or Phantom Help I get an error message...





Any idea ?

Thank you!
 
When I try to upload the TXT flight log on AirData or Phantom Help I get an error message
Follow my instructions here to locate the proper TXT file.
 
Did you just rename the log files? I can't load to AirData or Phantom Help log viewer.
So, you took off before you got good GPS lock. So it doesn't know where home is. I wonder if it was going to previous logged location. I guess when you search through this forum, you've come across a lot of this 'fly away' is caused by pilots not waiting for GPS lock, and didn't check compass calibration. i.e. pilot error.
I don't know how else to view your log files. Maybe someone else could.

The linked files are not txt logs. They may be RC logs.
 
Hi,

Thank you for your answers!

When I try to upload the TXT flight log on AirData or Phantom Help I get an error message...





Any idea ?

Thank you!

You are not uploading the correct files. You need to extract the txt log files from the mobile device FlightRecords directory as described in @msinger's instructions.
 
Hi everyone,

Until a few weeks ago, I was the lucky owner of a brand new DJI Mavic Air. But some days ago, I had the bad luck to live a FLY AWAY with my drone and was unable to find it back... which is a shame because I benefit from the DJI Care Refresh insurance.

I immediately contacted the DJI customer support to explain my issue and the technical failures of the drone. Below, you will find my first exchange of mails between DJI and myself. Of course, their first reply is that the incident was caused by an improper flight environment which is completely not correct (you will see my justification in the mails hereunder).

So I would like to have the opinion of professionals that are not working for DJI because I think that they are not completely honest and transparent with me.

On this Dropbox link, you will be able to find the logs of the 3 last flights of the drone (log 2 should be the last flight) : DJI Mavic Air logs - Symons

Some of you could give me their opinion based on the comments of DJI and the flight logs ?

Thanks a lot for you help and your good advices !

If you need any other information, do not hesitate to ask.

Kind regards,
Alexandre

Mail exchange with DJI :

1. My first mail :

"Hi, I bought a DJI Mavic Air from Media Markt Belgium: ordered on 03/03/2018 and received on 26/03/2018. On 30/03/2018 I subscribed to the DJI care refresh insurance via the official website DJI (Agreement No.: xxx). From this date, I started to use my drone and I did not notice any anomaly. I took my DJI Mavic Air with me for a trek on the island of La Gomera (Spain). During the 3rd flight on the island (13/04/2018), a major technical incident occurred. Indeed, after takeoff, several anomalies occurred and I decided to return the drone by pressing the button "Return to home". The drone did not react to this command and left in the opposite direction. Despite my various attempts to regain control of the drone, I did not succeed. According to my observations, the drone crashed on an inaccessible cliff. However, he reported a GPS position several kilometers from his take-off point, where I went the next day without being able to find him. I extracted the logs files of the last 3 flights of my drone, which you will be able to download to examine them in details at the following link: DJI Mavic Air logs - Symons I would like, as part of my insurance DJI care refresh, to obtain the replacement of my drone. I am well aware of the fact that I have not been able to recover the accident drone despite my efforts, but considering the nature of the technical failure and the place where it occurred I consider myself to be in the conditions of replacing my drone. Yours sincerely."

2. DJI answer :

"Dear Alexandre,

We are very sorry to hear about the unfortunate experience you have had with your DJI product. We will provide you with the best support possible.

Please follow the tutorial to sync your flight records to the DJI server. You can find the tutorial: HERE

The cloud icon at the end of the flight record indicates the flight record has been successfully uploaded. Once the sync is completed, please provide the following information to us so we can submit your report for data analysis:

- First and Last Name:
- Shipping Address:
- Phone number:
- Model of your aircraft:
- Serial Number of the remote controller:
- Email address associated with your DJI Account you used for your last flight:
- Date and time of the incident:
- Description what you did to try and regain control:
- Video Cached (Applicable if you are recording during the accident, please refer to the attachment and export it from your mobile device and upload to Google drive/Dropbox.)
- Proof of Purchase:

Note:
1. If you fail to sync your flight records to the server, please refer to the attachment and send us the flight records txt files on your mobile device. If it’s Mavic, please send us the RC log as well if the product is Mavic.
2. Flight records are important in judging the accident is pilot error or manufacturing error. If for some reasons, if you fail to provide enough information per requested, the warranty claim of the RTHF issue might be denied.
3. Flight records analysis would be accepted by DJI data analysis team only when the aircraft is within warranty period.
4. Once we confirmed that you have synced your flight records successfully, it will take 2 or 3 business days for us to finish the data analysis.

Thank you for choosing DJI.

Best Regards,
DJI Support"


3. My answer

"Hi,

I just uploaded the flight records to the DJI servers. Hereunder, you will find the requested information:

- First and Last Name: xx
- Shipping Address: xx
- Phone number: xx
- Date and time of the incident: Date 13/04/2018, Time 5.09 pm
- Description what you did to try and regain control: After takeoff, several anomalies occurred and I decided to return the drone by pressing the button "Return to home". The drone did not react to this command and left in the opposite direction. Despite my various attempts to regain control of the drone, I did not succeed. According to my observations, the drone crashed on an inaccessible cliff. However, he reported a GPS position several kilometers from his take-off point, where I went the next day without being able to find him.
- Proof of Purchase: See attachment.

On Dropbox, you will find the logs from the RC : DJI Mavic Air logs - Symons

Important reminder, I subscribed to the DJI Care Refresh for my drone (Agreement No.: xx).

Could you confirm me that the flight records were correctly uploaded and that you have all the information needed to handle my request?

Kind regards."

4. DJI answer

"Dear Customer,

Thanks for your patience.

For your claimed case CAS-1719134-L7D5D2, we have already finished the analysis, and the result is as follows:
1. The aircraft worked in OPTI mode after took off due to the weak GPS signal;
2. T=00:41, H=28.8 m, the aircraft switched to Atti mode;
3. T=01:14, H=-69 m, the aircraft crashed with obstacles and rolled over, then the flight record ended;
4. In Attitude mode, the aircraft could not hover in place, brake and avoid obstacle automatically.
According to the analysis, the incident was caused by improper flight environment. Please fly with caution.

We truly appreciate your support for DJI. If you could not recover the product and consider to purchase another aircraft, we can try to especially apply for a 15% off discount for Mavic Air(Arctic White)without charger and remote. If you would like to take the offer, please offer us the following info:
Shipping address:
Contact name:
Phone number:

Should you have more questions, please feel free to let me know.
Best Regards,
Lydia
DJI Tech Support

5. My last answer

"Good morning,

I received your last mail including your analysis of the accident of my drone DJI Mavic Air.

I have examined these analyses in detail. Please find below 3 points which prove that the accident of my drone is due to technical failures:

  • You indicate that at T = 00:41 the drone switched from OPTI mode to ATTI mode. According to the technical information, switching to ATTI mode occurs when the lighting conditions are bad. This was absolutely not the case as the flight took place at 5.09 pm so there was no reason to switch from OPTI mode to ATTI mode.
  • Your analysis indicates that at the time of the crash of my drone, the measured altitude was -69m which demonstrates that the drone was in a situation of major technical failure.
  • Your analysis does not explain at all why the drone, from a certain moment in this flight, no longer reacts to the commands and has gone in the opposite direction. This situation seems to be comparable with many cases of "Fly away" DJI Mavic Air that can be found on various forums:
https://mavicpilots.com/threads/mavic-air-fly-away.37558/
https://mavicpilots.com/threads/mavic-air-fly-away-what-gives.39521/
https://mavicpilots.com/threads/another-flyaway.37822/
Mavic Air flyaway!

Given all these elements, it seems clear to me that the crash of my drone is linked to a major technical failure. For this reason, I would like to benefit from DJI product warranty.

Thank you in advance for the attention you will give to my request."

Without seeing the logs I can tell you that -69m isn’t a failure that just means that the AC is 69m below the take off height.

Bad light situation doesn’t mean flying at night it means that the optical sensors doesn’t have enough light to work properly, ground without any distinctive pattern (even with good light) or that the AC was too high to use the optical sensors

If you mix any of the above scenarios with poor GPS you’ll get atti mode!

I’m not implying that is your fault just to clarify things

Anyone can correct me or add more info to these.

The only thing that will throw some light to the situation are those flight logs!

Sorry for your crash..
 
Hi everyone,

Thank you for your first feedbacks. Indeed, I was uploading the RC logs.
I tried with the logs that I got in the app but it still doesn't work... Here you will find the log, maybe I'm doing something wrong : DJI Mavic Air - Flight logs

I also got an answer from DJI to my last mail. Not convinced by they answer, they are not really responding why the drone did a Fly away.

Thanks for your precious help!

DJI answer:

"Dear Alexandre,
Thanks for getting back to us.
First, the data analysis should be based on case by case. Different customers have different flight environment and different pilot habit, so the result will also be different.
Second, the working mode is not only be affected by the light, but will also be affected by the flight environment such as the GPS signal. According to your flight record, it was clearly that the GPS signal bar was 0 almost from the beginning. Besides, the quality of the light is not only decided by the time, the aircraft would sense that automatically. And the warning of weak light also popped up on the app during the flight, which exactly indicated that the current flight environment was not suitable to fly the aircraft.
Third, as we have stated in User Manual, "The aircraft automatically changes to Attitude mode (ATTI mode) when the Vision Systems are unavailable or disabled and either the GPS signal is weak or the compass is experiencing interference. When the Vision Systems are unavailable the aircraft is not able to position itself or auto-brake, so potential flight hazards exist when flying in ATTI mode. In ATTI mode, the aircraft is easily affected by its surroundings. In ATTI mode, the aircraft is easily affected by its surroundings. Environmental factors such as wind can result in horizontal shifting, which may present hazards, especially when flying in confined spaces".
You may also check that from the link below (Page 11):

https://dl.djicdn.com/downloads/Mavic%20Air/20180213/Mavic%20Air%20User%20Manual_v1.2.pdf
The aircraft would drift in ATTI mode and that was why you felt it did not react to your command. But that was caused by the improper flight environment rather than the "technical failure " you claimed. Please do pay attention to the flight status before launching the aircraft.
Please email us the info required if you want the discount ready:
Shipping address:
Contact name:
Phone number:
Thank you so much for your support. Have a nice day.
Best Regards,
Lydia
DJI Tech Support"
 
Hi,

I finally found the right TXT file to upload on PhantomHelp : DJI Flight Log Viewer - PhantomHelp.com

Could you give me your feedback based on your observations ? What do you think of DJI answers ? Are they honest with me ? Do you have some arguments for me to prove to DJI that there was a technical failure with the drone ?

Thanks a lot !
Alexandre
 
Your drone never had a GPS lock. It doesn't know where it is or where home is, so RTH is useless. It was in ATTI for more than half the time, so it was drifting with the wind. If you could stick control from the RC, you might be able to bring it back, if you know how to fly in ATTI mode.
You shouldn't have taken off without GPS lock. If you had, someone here might be able to help locate it. And if located, and if it can be shipped to DJI, and if they found that the GPS module in your drone is faulty, they would've replaced it under warranty for free. But since you couldn't retrieve your drone, it's all speculation if it was technical fault. It started with pilot error.
If DJI gives everyone the benefit of the doubt for every crash, they'd go broke.
It drifted and hit something in the 1m10s mark at 94.5'?
 
Hi,

I finally found the right TXT file to upload on PhantomHelp : DJI Flight Log Viewer - PhantomHelp.com

Could you give me your feedback based on your observations ? What do you think of DJI answers ? Are they honest with me ? Do you have some arguments for me to prove to DJI that there was a technical failure with the drone ?

Thanks a lot !
Alexandre


Yes, DJI was honest and interpreted the logs fairly. You were flying without GPS lock and without a (correctly set) HomePoint. The aircraft was responding correctly to the few inputs you gave.
Without GPS and/or without a properly set HomePoint the RTH function does not and cannot work. without VPU and GPS it will also drift in the wind. like DJI wrote to you, all this behaviour is explained properly in the manual.

my analysis of the flight:
You took off without GPS lock (no HomePoint set). For the first 38 sec it was able to use VPU to keep the drone in place even without GPS. But the VPU only works with enough light, low to the ground and with enough contrast in the surface. At 38 sec into the flight the VPU was no longer able to keep position (mainly because you increased altitude to ~30m) Without VPU and without GPS it entered ATTI mode and starts to drift in the wind. While in ATTI mode there was almost no attempt to fly the still fully controllable drone. After a few throttle inputs and one elevator input until it crashed. It looks to me like it drifted into a hillside.

Because you have DJI care your only chance is to recover the drone and claim your DJI care, which would cover this event, no questions asked.
 
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@laurens23 accurately summarized the flight. Here are the supporting data:

The satellite count was 6 for most of the flight, reaching 7 just before it crashed, and GPS health was zero throughout, probably due to the cliffs that you were flying next to. The aircraft started in OPTI but switched out when the flight altitude was around 30 m - too high for VPS to function.

2018-04-13_[17-09-01]_01.png

The aircraft responded correctly to all inputs, other than ignoring throttle once it reached the set maximum of 30 m. It appears that you made no significant effort to control the aircraft.

2018-04-13_[17-09-01]_02.png

2018-04-13_[17-09-01]_03.png

2018-04-13_[17-09-01]_04.png

I cannot see why DJI would accept any liability for that event.
 
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@laurens23 accurately summarized the flight. Here are the supporting data:

The satellite count was 6 for most of the flight, reaching 7 just before it crashed, and GPS health was zero throughout, probably due to the cliffs that you were flying next to. The aircraft started in OPTI but switched out when the flight altitude was around 30 m - too high for VPS to function.

View attachment 37175

The aircraft responded correctly to all inputs, other than ignoring throttle once it reached the set maximum of 30 m. It appears that you made no significant effort to control the aircraft.

View attachment 37176

View attachment 37177

View attachment 37178

I cannot see why DJI would accept any liability for that event.
What app you use fir the graphs?
 
@sar104 being that no HP was set, could it be possible that the previous home point could be still recorded??? I tried to extract it but it csview says not recorded, so I'm assuming that there simply is no HP that the FC would attempt to go to.
 
@sar104 being that no HP was set, could it be possible that the previous home point could be still recorded??? I tried to extract it but it csview says not recorded, so I'm assuming that there simply is no HP that the FC would attempt to go to.

The aircraft did not record a home point. In any case, it didn't attempt to go anywhere - it simply drifted in ATTI and crashed after 70 s. The flight location was below some cliffs rising to over 100 m, which is likely the reason for the poor satellite count.
 
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My Mavic doesn't leave the ground unless it is in GPS mode and has acquired at least 10 satellites. Period. And in the rare event it loses GPS lock while flying, I manually land it IMMEDIATELY. Which is easy because I *always* keep my Mavic in visual LOS.

Sometimes my Mavic sits on the ground for what seems like 5 minutes as I wait for GPS lock. It's probably 1-2 minutes at worst and 30 seconds to 1 minute on average. That wait can feel intolerable sometimes. But wait it out I do.

Mark
 
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