Hi all, I took my Spark out on this foggy morning (approx 1/2 mile visibility) to do some through the fog video's.  I sent it up about 200ish feet when I knoticed the altitude was going crazy.  When I brought Sparky back down it was coming down at a high rate of speed and was not going to stop after I let off the controls, I was able to push up on the stick and it finally stopped.  I landed and restart everything and tried again.  Altitude seemed to be accurate at about 10 ft then went crazy again beyound that.  Also, Sparky wanted to keep climbing and or decending for a brief moment after letting off the sticks.  I re-started everything again, fresh battery, and re-calibrated the compass and the issue still presist...any ideas as to whats going on?  Could it be the fog messing with the GPS signal?  I forgot to look at how many satalites I had.

Thanks
Brian

Check out your TXT flight log to see if it explains what happened. You can upload and view it online here. If you'd like other people to review and comment on your flight log, then please post a link back here after you upload it.

Perhaps baro and vps had confusing readings.
Usually vps gets to "0", during a flight in higher altitude.
Fog can trigger readings in the <30 feet area, even if 100/200 feet up.
But usually that stops the bird from decending in normal speed, it gets stucked in slower "landing mode"
Upload the flight record, like msinger suggested and check it out, post the link in another post of you.
Have you been in Sport?

msinger Posted at 11-3 08:16
Check out your TXT flight log to see if it explains what happened. You can upload and view it online here. If you'd like other people to review and comment on your flight log, then please post a link back here after you upload it.

Sparky record 11/3/2018


I had this flight last night which was flawless.
Sparky record 11/2/2018

Do you have any accessories installed beneath your drone (like extended landing gear)?

msinger Posted at 11-3 09:06
Do you have any accessories installed beneath your drone (like extended landing gear)?

Yes, I have about 1" tall legs on each arm.  They've been on it for months without any issues.

Update....

The fog has lifted and Sparky is back to normal.  I guess I can't fly through fog

Thank you!
Brian

Hiya,

As others have said "FOG" and i agree with them ; and it shows in the chart


cheers
JJB

Page 46 of the user manual states "Do not use the aircraft in severe weather conditions. These include wind speeds exceeding 10 m/s , snow, rain & fog."

Basically, the vision system detects the fog as ground. This can be seen in the log with the erratic VPS altitude readings v's the IMU altitude.  

From personal experience, descending through the edge of a low cloud,  Spark becomes confused & turned off the downward sensor.  During auto landing, Spark failed to slow down & landed harder than normal..
Apart from the hard landing, Spark was always controllable - lucky,  Spark didn't attempt to actually land on the cloud!
My logs showed when the VPS detected the cloud & turned off the downward sensor. The final IMU altitude logged was 12 ft when it should show 0 ft - Spark was on the ground.  Accumulated error?  https://en.wikipedia.org/wiki/Inertial_measurement_unit

Any reflective surfaces below Spark may also cause problems. Be careful over water & snow.
Good luck & safe flying.

Twistedlarch Posted at 11-3 09:57
Update....

The fog has lifted and Sparky is back to normal.  I guess I can't fly through fog

Had the same symptoms when I tried to fly through fog, which resulted in a heavy, hard landing. Also had a Sensor Error message. Did you perhaps have any message related to the Sensor??

Flighty Posted at 11-5 00:28
Had the same symptoms when I tried to fly through fog, which resulted in a heavy, hard landing. Also had a Sensor Error message. Did you perhaps have any message related to the Sensor??

No error messages what so ever.

Twistedlarch Posted at 11-3 09:57
The fog has lifted and Sparky is back to normal.  

It sounds like you found the cause of the issue.

Unfortunately, the Landing Protection setting cannot be disabled in DJI GO when flying the Spark. That needs to be turned off in order to prevent those unwanted altitude changes.

Valuable thread.... thanks to everyone who looked at it and shared interpretations.  I learn, and learn, and learn :-)