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Would not stop climbing on RTH; Obstacle warning
2616 11 2017-1-28
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Alan E
lvl.3
Flight distance : 6457 ft
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United States
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Hello,
Did my first flights of my Mavic today. I did several RTH automatic landings that went perfect. Later that morning in the same location, I tried out the Active Track and POI features; that worked perfectly. I did some manual flying after that in GPS mode. I then flew away from the home point (about 200 feet) as before and hit the RTH button. The Mavic initiated it's climb as before (RTH altitude set to 25m) but this time it would not stop climbing! The RC was displaying "Obstacle", but there was no obstacle. I cancelled the RTH at 225 feet and then brought it down manually. This non stop ascent freaked me out!
This was at 11:30 and not into the sun; although the sun was bright. I read about a pilot leaving the shipping film protectors on the sensors; mine were removed.
I am sure this is some kind of pilot error but I can not figure out what.
Thanks for any ideas,
Alan
2017-1-28
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Alan E
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Went flying again today and the same thing happened. I activated RTH (altitude set again to 25m). I was expecting this today so I was ready to cancel RTH if she started to climb beyond 25m. I stopped it much sooner at 128 feet.
Here are the flight logs for yesterday's and today's RTH incidents.
Thanks.

1/28/2017 RTH climb beyond set altitude

1/29/17 RTH climb beyond set altitude
2017-1-29
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thehippoz
Captain
Flight distance : 23 ft
United States
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Facing the sun? This time of year the sun is pretty low still. It sets off the forward obstacle sensors. I'm not sure healthy drones records this or not but it'll show obstacle up in the air during flight. I turn them off.
2017-1-29
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Alan E
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thehippoz Posted at 2017-1-29 14:17
Facing the sun? This time of year the sun is pretty low still. It sets off the forward obstacle sensors. I'm not sure healthy drones records this or not but it'll show obstacle up in the air during flight. I turn them off.

Thanks for your thoughts on this. Could be. I did see a lot of lens flare on the video from today. It wasn't directly into the sun but maybe close enough.
I will experiment more.
Does anyone know the easiest method to turn off the sensors while flying?
2017-1-29
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Heavysledz
Second Officer
Flight distance : 631096 ft
United States
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next time, try switching it into sport mode and see if that corrects it. Sport mode will disable the forward vision sensors so if that is the issue, you will know immediately.
2017-1-29
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hallmark007
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Flight distance : 4802917 ft
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Ireland
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Alan E Posted at 2017-1-29 14:25
Thanks for your thoughts on this. Could be. I did see a lot of lens flare on the video from today. It wasn't directly into the sun but maybe close enough.
I will experiment more.
Does anyone know the easiest method to turn off the sensors while flying?

It may well be the sun, the Mavic will climb to clear obstacles when in RTH you maybe should try from a different direction to see if it might be the sun.
You can turn off OA but not when in RTH as far as I know. On your first you had also slight problems loosing radio control and slipping out of gps to Atti, although you had only 11/12 sats first day , second day no problem with loosing signal.
Good luck..
2017-1-29
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Alan E
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Tried sport mode this time
Took off and flew a few meters away. Turned Mavic back to face me; sun pretty high and at the Mavic's 2 o'clock. In GPS mode. Initiated RTH and it started, stopped, climbed beyond the RTH setting of 25m. I switched to Sport mode as suggested so the sensors would be turned off. This cancelled the RTH. Re-initiated the RTH while in sport mode and the same thing occured. Start towards home, stop, climb even higher beyond the RTH altitude setting. After a bit of this, the Mavic returned home.
Keep in mind that I love my Mavic! I just want to get this bug fixed.
Right after this flight I did another one and initiated the RTH from a spot where the Mavic was looking completely away from the sun. RTH worked perfectly without hesitation or climbing over the RTH set altitude.
2017-2-4
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Jason Lane
Second Officer
Flight distance : 260144 ft
Australia
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If you were in Sports mode then I assume you no longer got the obstacle warnings that you mentioned in your first post, since the forward sensors are disabled. Correct? If it's climbing too high without any on-screen obstacle warnings, I can think of two possible reasons:

1. You have the VPS issue that many others have experienced, causing the Mavic to think there's something below it. This is not disabled in Sports mode. However, if this were the case, you'd probably also be experiencing unintentional ascending during other phases of flight, not just RTH. See this thread: http://forum.dji.com/thread-77495-1-2.html

2. I've reported an apparent bug where the Mavic just sometimes seems to ignore the set RTH altitude. I've seen it both ascend way past the set height, and even ascend too low on one or more occasion. In my testing, there were absolutely no errors, no problem with the VPS or any other sensors. Height was always reported correctly, but the Mavic simply rose to the wrong altitude. See this thread: http://forum.dji.com/forum.php?mod=viewthread&tid=75543
2017-2-4
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Alan E
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Jason Lane Posted at 2017-2-4 18:08
If you were in Sports mode then I assume you no longer got the obstacle warnings that you mentioned in your first post, since the forward sensors are disabled. Correct? If it's climbing too high without any on-screen obstacle warnings, I can think of two possible reasons:

1. You have the VPS issue that many others have experienced, causing the Mavic to think there's something below it. This is not disabled in Sports mode. However, if this were the case, you'd probably also be experiencing unintentional ascending during other phases of flight, not just RTH. See this thread: http://forum.dji.com/thread-77495-1-2.html

Thanks Jason for the detailed response. I did not check to see if the obstacle warning appeared as before. It did exhibit the same behavior; lurch forward, stop suddenly, climb, repeat.
2017-2-4
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Butterfingers
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Australia
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Hi guys - I had a similar problem today with RTH. Yesterday I had no problems with RTH, but today I hit RTH and the Mavic oriented towards me, moved about halfway towards me (it was about 30m away, then started climbing way beyond the 30m RTH set height. I cancelled RTH and brought it back and landed it, then tried again. Flew away and hit RTH - same thing, but this time I let it go and it eventually stopped climbing when it hit the 120m max altitude, so I cancelled RTH and brought it home manually.

I'm not sure if this is being caused by a low-level crash that I had yesterday. Drone was at about 2' off the ground, flying backwards and was blown into a wall by a heavy wind gust. Drone flipped over and engines continued running. Picked it up, turned it over and motors stopped. Prop blades a bit scratched and a scratch on the top of the battery. Set it down and initiated take off. No problem - straight up into a hover. Flew backwards, side to side and forwards, plus yaw left and right - all okay, except that forward tilt and speed minimal. Forward speed no more than 2m/s. I've since recalibrated the compasses and the IMUs, but no change.

Any ideas or suggestions?
2017-2-4
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Alan E
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Alan E Posted at 2017-2-4 20:50
Thanks Jason for the detailed response. I did not check to see if the obstacle warning appeared as before. It did exhibit the same behavior; lurch forward, stop suddenly, climb, repeat.

So I did 2 more RTH tests today with perfect results. It is overcast today with no sun.
Every time the stopping and climbing over the RTH set altitude symptom has occurred, it has been with the Mavic heading into the direction of the sun. Turn around and approach the home spot with the sun to the Mavic's stern and RTH works fine.
I am now positive that false readings of the sunlight being sensed as an obstacle are the problem.

So that being solved (well understood), my next mystery to solve is why turning on sport mode did not stop the Mavic from sensing the sunlight as an obstacle.
I will do more tests to confirm because I only tested sport mode in the direction of the sun one time.

2017-2-6
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Adi98
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Had a similar problem with my Spark. Flew it during the morning at 7am with the sun shining bright. Got about 100 m out and was at 80 m height, when I started to notice obstacle avoidance warnings even though there was nothing around it. It initiated RTH and climbed way above 100 m which was my set RTH altitude. I tried cancelling RTH multiple times, but it would briefly disengage before reengaging RTH. And my inputs were useless (probably due to the obstacle detection). Turned on Sport mode and somehow managed to get it back. Any thoughts?
2019-9-30
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