Hey guys,

I'm sure this happens a lot and if this is a repeat of of a thread that I have not come across in the previous threads, my apology for my ignorance and a link to help me better understand would be of great education!

I've been flying my Spark for a little over a year now (14hr flight time/65km/multiple countries if that helps) and have watched a ton of Youtube videos to learn do's and don'ts. I pride myself on being able to equip myself with such knowledge as well as be able to practice it out in the field and learn from my humble shortcomings as a human.

During my warranty period I had many random disconnects and loss of transmission so the Spark would RTH at times when it would not reconnect within a second.  I had sent in inquiries of this to DJI with ZERO follow-up. It wasn't a big enough problem for me to pursue them because I was within my warranty period and thought if it happened more, I would attempt to start communication again. Presently if this happened before taking off, I would restart the remote or the Spark and I'd wait a minute to make sure it was stable then I would take off as soon as I could set RTH.

This time, I was getting some footage and realized after I landed, that I didn't hit video record for one last video clip and my battery was red after landing it. I put a freshly charged battery in and made sure all clips were solid. I started Spark up again to get that one final video. Once I got satelittes and RTD location/altitude verified, I started Spark up into the air for one simple forward in Sport and incline at max speed like I just did in the previous battery to create a reveal shot. After about 400ft away the picture went blank and the remote went red and my GO4 app verified if I want to return to home. I slide it over to say, yes, but it didn't matter because the remote showed a red LED and zero connection. I didn't worry because I know whenver my Spark lost remote connection it would just RTH, so I waited patiently to hear buzzing overhead since it was less than 400ft away and less than 100ft high from my starting position. After 1 minute, nothing.  After 2 minutes, silence. I got worried and looked down on the remote showing a red LED. I hit RTH on the remote but that didn't help. After 5 minutes I patiently gave up that it was coming back.

I launched and set my RTH point at the highest point of my intended trajectory so if RTH had to be initated the Spark would rise to my 30m set altitude even though it didn't have to because there is nothing in the way in my direct line of sight maneuver. There were some trees around but they might have been 5m higher than the take off height which is a non-issue for my RTH settings. Even if it RTH with no altitude change it was already 97' above where my location was. I just used the phantomhelp website and uploaded my flight log to the sight but it doesn't show any anomalies.  The Spark and exterior conditions were nonimal including battery voltages (11.26V) for each of the three cells with a 0.028V deviation at 92% capacity when it lost conact.

Because the last known whereabouts were over the ocean, I made the decision that because I had only 2 hours to get to the airport to catch my international flight, I would not attempt to scuba dive for Sparky. LOL. It would have dropped into the ocean where the depths quickly range from 16.4' to 37.7'. The weather conditions were perfect with light wind and clear blue skies.  I did not have any visual of Spark because it's so small, even at 100ft away, you lose visual of it and after a couple hundred feet you stop hearing the propellors cutting the air. I do have my flight data and I do have the streamed 720p video up until the remote LED went red.  The steamed video showed zero sign of aerodynamic disturbance/physical parts failing and there were no large birds in the area to have swooped and grab Spark let alone having any bird try to catch up immediately with a 53km/h at max cimb rate. My maneuver from RTH point only took 11 seconds until loss of signal.

Now I want to find out if DJI or any other users with more experience can help me learn WHY my Spark react the way it did and what are the supporting reactions for RTH to become disabled when remote connection is lost?

PS. Thank you ahead of time for taking the time to read my "as much accuracy as I can", story.

Hi roverT, we are so sorry for your loss and thank you for the details of the whole flight process, please contact our support team www.dji.com/support to start a ticket and see if the data analysis can be applied, thank you.

Most of the cases like this I've seen turned out to be caused by high wind pushing the aircraft out to sea, but the best thing to do if you'd like more information is to retrieve the flight log from your mobile device, upload it to PhantomHelp using these instructions, and then post a link to the uploaded log in this thread. That will provide us with a lot more information on what was happening when you were still connected to the aircraft, and in turn allow us to make an educated guess regarding what happened. Until then all we can offer is speculation.

Gimpy Posted at 9-17 02:52
Most of the cases like this I've seen turned out to be caused by high wind pushing the aircraft out to sea, but the best thing to do if you'd like more information is to retrieve the flight log from your mobile device, upload it to PhantomHelp using these instructions, and then post a link to the uploaded log in this thread. That will provide us with a lot more information on what was happening when you were still connected to the aircraft, and in turn allow us to make an educated guess regarding what happened. Until then all we can offer is speculation.

Here is my flight log of the last flight of my Spark:

https://www.phantomhelp.com/LogViewer/6PB92IJU105Z184LMXSD/#

I can't see it as high winds.  I flew quite early in the morning just after sunrise.  The previous battery I was in the air for the whole battery flying in the same location and altitude with totally calm/perfect conditions.  I've flown in much windier environments with the Spark being totally OK.  I've had a couple of high altitude flights where the app messaged me there was high wind so I lowered the altitude immediately to a more stable layer of air.  What is weird that I can't understand was the sudden loss of all communication with no sign of RTD. Still very confused.

DJI Mindy Posted at 9-17 01:08
Hi roverT, we are so sorry for your loss and thank you for the details of the whole flight process, please contact our support team www.dji.com/support to start a ticket and see if the data analysis can be applied, thank you.

I want to be able to click the right thing for the best response.  What options do I choose? After sales service has no such link to move further. I don't have DJI care and there is nothing physical to repair.

roverT Posted at 9-17 15:31
Here is my flight log of the last flight of my Spark:

https://www.phantomhelp.com/LogViewer/6PB92IJU105Z184LMXSD/#

Yes, the winds at that location were estimated to be at around 17 KPH near ground level and would probably have been a bit higher at the roughly 30m above ground where your Spark was flying. It was almost due east of you and the winds were to the southeast, so it almost certainly would have struggled to return.

As for the loss of connection, I've seen a number of things blamed for lost links, including using an unsupported mobile device, a bad cable (usually the DJI-supplied one) between the mobile device and phone, a need to put the phone into airplane mode before flying, etc. If you get a replacement, I'd recommend flying in relatively safe areas and making sure you don't have connection problems (or diagnosing and addressing them if you do) before going out over the water again, because as you've unfortunately found out, it's a very unforgiving place to have something go wrong.

Gimpy Posted at 9-17 16:50
Yes, the winds at that location were estimated to be at around 17 KPH near ground level and would probably have been a bit higher at the roughly 30m above ground where your Spark was flying. It was almost due east of you and the winds were to the southeast, so it almost certainly would have struggled to return.

As for the loss of connection, I've seen a number of things blamed for lost links, including using an unsupported mobile device, a bad cable (usually the DJI-supplied one) between the mobile device and phone, a need to put the phone into airplane mode before flying, etc. If you get a replacement, I'd recommend flying in relatively safe areas and making sure you don't have connection problems (or diagnosing and addressing them if you do) before going out over the water again, because as you've unfortunately found out, it's a very unforgiving place to have something go wrong.

How do you find historical data of wind at any location?

I've experienced wind pushing my Spark on video as I counteracted it only one time but video feed stayed alive and it was simple to just adjust altitude and bring the drone back in sport mode. The wind conditions on the ground were enough to make flags fly at full staff but even in non-sport mode the drone didn't show sign of instability and can easily hover which made me not even think of that this time since it was calm.

When I was out there it was the most peaceful morning ever.  I assume it was just after sunrise so the grounds have not heated up enough to create any large updrafts nor was there any weather system influencing any sudden drops of pressure which could create wind.  Wind felt non-existant at the time I was out.

Here is my previous flight data a few minutes before which was totally normal exploring the area in more depth: https://www.phantomhelp.com/LogViewer/WJSVSD0HRVLLR2K8CS9Z/

I was getting some amazing views and I could just hover without any wind warnings.  Nothing ever felt rushed while I was in the air.

This is what my Spark streamed as it's last 30 seconds of control:
https://www.dropbox.com/s/65kitlqasbkupge/2019-09-14%2014.43.30.mp4?dl=0

I was connected via my iPhone 7+ with a full battery using wifi to connect to the DJI remote which was also full battery. I'm OCD about keeping everything charged up prior to going out on a journey.  I've flown with different variations of bluetooth/airplane mode/wifi with a cable and without a cable.  My experience in all variations have been the same and totally solid which is why I'm still befuddled as to why the drone just disconnected on a completely stable 30fps video (no dropout) feed and never came back. If someone shot it, I think I would hear the shell...haha.  

roverT Posted at 9-17 22:09
How do you find historical data of wind at any location?  

I've experienced wind pushing my Spark on video as I counteracted it only one time but video feed stayed alive and it was simple to just adjust altitude and bring the drone back in sport mode. The wind conditions on the ground were enough to make flags fly at full staff but even in non-sport mode the drone didn't show sign of instability and can easily hover which made me not even think of that this time since it was calm.

The easiest way for most people is to check wind speed is to upload the flight log to AirData and check what it says. There are also subscription services for obtaining the information, and I'm guessing that's what AirData uses.

Although wind may have been the cause, it's not the only possible explanation. For example, another possibility is that there was a complete and spontaneous power loss, though to investigate that I'd need you to upload a separate file, specifically the DAT file that's also on your mobile device, and the correct one will be FLY195.DAT. The instructions for retrieving it are found here.

roverT Posted at 9-17 15:37
I want to be able to click the right thing for the best response.  What options do I choose? After sales service has no such link to move further. I don't have DJI care and there is nothing physical to repair.

Email, online chat both are fine, please select either one to reach out our support, the team will help, thank you.

Gimpy Posted at 9-18 14:50
The easiest way for most people is to check wind speed is to upload the flight log to AirData and check what it says. There are also subscription services for obtaining the information, and I'm guessing that's what AirData uses.

Although wind may have been the cause, it's not the only possible explanation. For example, another possibility is that there was a complete and spontaneous power loss, though to investigate that I'd need you to upload a separate file, specifically the DAT file that's also on your mobile device, and the correct one will be FLY195.DAT. The instructions for retrieving it are found here.

Let's give this a try: https://cl.ly/ffa6d6594007
Again, thank you so much! The internet community is an amazing tool when good minds can come together as one to answer a question/problem.

roverT Posted at 9-24 22:26
Let's give this a try: https://cl.ly/ffa6d6594007
Again, thank you so much! The internet community is an amazing tool when good minds can come together as one to answer a question/problem.

I did look at the DAT file but I'm sorry to say that I'm not sure what went wrong. I didn't see any abrupt changes in velocity near the end of the log that might have caused a loose battery to trigger a power loss or any other indication of what went wrong. People like to throw out the bird strike theory, especially in cases involving flying around water, but from what I call tell, bird / drone collisions are really very rare. Plus, I would think that there would be some indication of this at the end of your log files but I saw none. My best guess is that there was a sudden loss of power, but I would have thought there would be some affirmative indication of that happening in the logs. Instead what I found is that the logs just ended abruptly while everything seemed normal, though that may be what's expected in the case of a sudden power loss and I just haven't seen it enough to recognize it.

I would suggest that you send a Personal Message to the guy who wrote the tools I used to look at your log files, namely BudWalker and see if he'd be willing to take a look. He seems to lurk around this form, and it's very possible that he might see something that I overlooked or didn't recognize the significance of.

Good luck.