Hi.  My DJI Spark drone is about 1 month old (from purchase -- the Spark itself was manufactured in October 2017 according to serial number checking webpage).  So far no issues, until yesterday.  I waited until there were enough GPS satellites,  made sure that status was Ready to Fly and recorded the RTH position.  Flew about 100ft, line of sight, relatively good weather (cloudy), same area I always fly without issues, when I lost connectivity, video feed is lost and I see thast the Spark starts to RTH.  It later reconnected, I cancelled RTH and took control of the Spark.
All the components are up to date (Spark, batteries, RC, App, iPhone).  By the way, I updated the iPhone X to iOS 12 the night before the incident.  I'm connecting the RC to the iPhone via OTG cable.  Wifi and Bluetooth are disabled during flight.

Today, the Spark is operating normally.  But I'm worried about the incident.

Can someone review my Flight Log?  Anything there that can give us a clue of what could have happened?

Your help is appreciated.

Link to flight log, hope it works:  http://www.phantomhelp.com/LogViewer/F8V9C13VAJPZAQNMWGCD/

It seems that your RC Signal was blocked by the house. and also number of GPS sat quantity too low during takeoff.
See signal pic.

62+ Posted at 2018-9-25 19:30
It seems that your RC Signal was blocked by the house. and also number of GPS sat quantity too low during takeoff.
See signal pic.[view_image]

Thanks for the response.  Do you think that a bad OTG cable might have something to do with the issue?  I inspected the cable and one of the connector (lightning side) pins was dirty/rusted.  I replaced the cable and did not have any disconnections today.  But it may be unrelated.

For instance, what happens if I have the RC and iPhone connected via OTG with both Wifi and Bluetooth disabled and disconnect the cable midflight?  I would have the same behavior?  (disconnect and RTH)

GPS SATS

Trust this info helps. I'm no expert.

Safe flying

Rimsky Sucre Posted at 2018-9-25 19:37
Thanks for the response.  Do you think that a bad OTG cable might have something to do with the issue?  I inspected the cable and one of the connector (lightning side) pins was dirty/rusted.  I replaced the cable and did not have any disconnections today.  But it may be unrelated.

For instance, what happens if I have the RC and iPhone connected via OTG with both Wifi and Bluetooth disabled and disconnect the cable midflight?  I would have the same behavior?  (disconnect and RTH)

Bad OTG connect could cause this as far as I understand.

See warning of OTG cable.
Fly safe.

62+ Posted at 2018-9-25 20:34
See warning of OTG cable.
Fly safe.

Nice video, do you fly with the OTG currently?

Yes only recently. But using Android. Working fine to date but one carefull all the time. Had few strange things since I got the Spark. But is it is still 100% after many fights 91km.

Hi. Thank you for reaching DJI Forum. Did you notice if there was an error message that appeared in the app?

Hi Wanda.

No. I just noticed that the app screen went mostly black and I immediately focused on the Spark.

I just did a quick test flight, disconnected the OTG cable and the behavior wa a different. This time the Spark remained hovering and I could control it with the RC sticks. Just video was obviously lost. I reconnected the OTG cable and video returned. All good.

It seems that something different happened during the incident. It seems that GPS and/or RC - Drone connection was lost.

I would like to get to the bottom of it, if possible. Can we get more information from another log?  Perhaps from the drone itself?

I did another test flight, disconnecting the OTG cable longer, just in case.  Since the issue shows a disconnect of 28 seconds and my first test today it was manually disconnected for less time.  Now it was disconnected for 50 seconds.  The error is the same (Downlink data connection lost), but the behavior is not.  During the incident, the Spark decided to RTH by itself.  When I manually disconnect the OTG cable, it stays hovering and does not enable the RTH mode even after 50 seconds.

A        00m 00s        0.0 ft        0 ft        Mode        Mode changed to Motors_Started
B        00m 00s        0.0 ft        0 ft        Tip        Setting new Return-To-Home altitude to 30m (98 ft). Data Recorder File Index is 96. Setting new Maximum Flight Altitude to 120m (394 ft)
C        00m 01s        0.0 ft        0 ft        Mode        Mode changed to AutoTakeoff
D        00m 02s        0.7 ft        1 ft        Tip        Home Point Recorded. RTH Altitude:  30m.
E        00m 03s        4.3 ft        1 ft        Mode        Mode changed to P-GPS
        00m 21s        53.1 ft        72 ft       

80% Battery
F        01m 32s        83.7 ft        127 ft        Data Loss        Downlink data connection lost for 50.7 seconds
        01m 36s        84.0 ft        128 ft       

71% Battery at maximum distance
        01m 40s        84.0 ft        113 ft       

70% Battery
G        01m 44s        84.0 ft        115 ft        Mode        Mode changed to Go_Home
H        01m 44s        84.0 ft        115 ft        Tip        Aircraft is returning to the Home Point. Minimum RTH Altitude is 30m. You can reset the RTH Altitude in Remote Controller Settings after cancelling RTH.
I        02m 09s        99.1 ft        1 ft        Mode        Mode changed to AutoLanding
J        02m 54s        1.0 ft        21 ft        Mode        Mode changed to Confirm_Landing
K        02m 57s        0.0 ft        20 ft        Mode        Mode changed to P-GPS

Just be very careful.

The RTH behave differently depending on the distance from the home point.
Just use RTH in case of emergency and learn how to control the AC with the remote. ATTI  mode. See below.

See also below tread.
You must know where your drone is at all times. Fly VLOS at all times or you may not have time to take corrective action in time.
The total system that everyone is using is diffent even if you use the identical hardware. Lots of factors at play.  Enviroment, (weather, inteference, pilot experience, etc) This is just my personal view point. After 4 months and more than 300 flights I'm still learning something new every day. The Spark is not a toy in my eyes but a very complex piece of technology and the more you know about it the lower the risk of pilot error.
Safe flying.

Study the DJI manual and the infomation on this forum as can be very usefull.

https://forum.dji.com/thread-114617-1-1.html

62+ Posted at 2018-9-26 11:02
Just be very careful.

The RTH behave differently depending on the distance from the home point.

Hi 62, thanks for your replies.

Do you think that if I repeat the test of disconnecting the OTG when the Spark is at a longer distance from me (and homepoint), then I should be able to reproduce the issue?  I want to try it because I really want to understand what happened.

I would rather not even try it unless you have a big open area.
Why force an error ?
The change is always thier that things go wrong and you damage or loose you Spark.
Make sure that all pre-flight checks are done before you take off and just enjoy the Spark and its many functions.
Notice that you use the latest App. and an iphone.
Remember that it need to be "evaluate" by the users.
I am using Android and older version of the App. As it seems to be the most stable with my phone model.
Maybe some iphone users can give you more sound advise.

62+ Posted at 2018-9-27 06:38
I would rather not even try it unless you have a big open area.
Why force an error ?
The change is always thier that things go wrong and you damage or loose you Spark.

I want to test it because I'm worried that it can reoccur at the worst unexpected moment.  If it happens during my test, then I'm prepared to take action, the risk is reduced.  If I can't reproduce the issue, then I'm not sure what caused it and it is something that is there latent to happen anytime.  Versus if I positively conclude that it was the old OTG cable, then I can have some peace of mind.

Hi Rimsky Sucre ,
I understand and respect your reasoning.
Please provide feedback on your results.

Fly safely my friend.

with only 7 satellites to start i would have moved to a different location and waited for at least 10 or more satellites .

NRRTrains, I take the recommendation, but do you think that the lack of GPS satellites had something to do with the video feed disconnection?  I think that something else happened.  The Spark already got more GPS Satellites when the issue happened.

Duplicated Post.