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Drone in RTH ascending way over set limit
1305 8 2022-11-19
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unound.one
lvl.1

Croatia
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An hour ago I had my first real flight using Phantom 4 and something happened which I can't understand.

After that I learned about flight data log, and even lookin at log I don't see anything abnormal but still can't comprehend this behaviour.


So here it is :


I'm flying the drone in P-GPS mode, home distance 539.0ft, alt is 114.2ft and I hit RTH.



RTH height is set to 60m in app.



log reads :  RTH: Heading alignment.; Aircraft is returning to the Home Point.  RTH Altitude is 60m. You can reset the RTH Altitude in Remote Controller  Settings after cancelling RTH if necessary.



2 seconds afer it reads : RTH: Ascending to RTH altitude.



everything fine until this point because it was lower than set attitude.



It doesn't stop rising after 60m (196ft)


At one point it reaches 397.0ft so i get : Altitude above the takeoff point exceeds 120 . Always fly in compliance with altitude limitations.


It's still rising , at 442.9ft i get : Maximum Flight Altitude Reached.


So i start to panic and hit sticks and in log I see it switches to  P-GPS so I manually descend and land it safely.

Does anyone have any explanation why this happened? Log is not usefull in this instance.




2022-11-19
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Labroides
Captain
Flight distance : 9991457 ft
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Australia
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Log is not usefull in this instance.
There's much more information available in the recorded flight data and it could be very useful.
Post your flight data so others can dig deeper into it.

Go to http://www.phantomhelp.com/LogViewer/Upload/
It has instructions to find the .txt file from your phone or tablet which you can upload to that site
Upload it and it gives you a summary of the flight data.
Post a link to that summary.

Or just post the .txt file



2022-11-19
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unound.one
lvl.1

Croatia
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Labroides Posted at 11-19 15:24
Log is not usefull in this instance.
There's much more information available in the recorded flight data and it could be very useful.
Post your flight data so others can dig deeper into it.

Here it is :
https://www.phantomhelp.com/LogViewer/8RF7QJDOP1YSP9XFAYM7
2022-11-20
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Labroides
Captain
Flight distance : 9991457 ft
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Australia
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When you initiated RTH, the drone turned to face the home point and started to climb to the RTH height.
It climbed past the 60 metre RTH height that was set and kept climbing until it reached the 135 metre Max Altitude limit which you had set.
It stayed hovering at that height.
It never started flying toward the home point.

The most likely explanation for this incident is obstacle avoidance reacting to a false obstacle indication.
These are usually caused by the sun.

You could do a little testing at lower altitudes to see if you can repeat this with RTH in a different direction, with and without obstacle avoidance operating.
2022-11-20
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unound.one
lvl.1

Croatia
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Labroides Posted at 11-20 13:31
When you initiated RTH, the drone turned to face the home point and started to climb to the RTH height.
It climbed past the 60 metre RTH height that was set and kept climbing until it reached the 135 metre Max Altitude limit which you had set.
It stayed hovering at that height.

Wouldn't obstacle avoidance activation be shown in the log?
I don't see it in log, nor I remember showing any obstacle warning during ascend.
I'll try again for sure and see if it will activate again.
2022-11-21
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Labroides
Captain
Flight distance : 9991457 ft
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Australia
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unound.one Posted at 11-21 01:16
Wouldn't obstacle avoidance activation be shown in the log?
I don't see it in log, nor I remember showing any obstacle warning during ascend.
I'll try again for sure and see if it will activate again.

The recorded data shows lots of things, but OA isn't one of them.
2022-11-21
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Tizzy
lvl.3
Flight distance : 1307247 ft

United States
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This happened to me today, exactly.

Recently updated FW, formatted aircraft SD card, added SD to android device also and set cache limit to auto.  Almost certain that RTH has worked acceptably in the past with this P4.
2023-4-30
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Tizzy
lvl.3
Flight distance : 1307247 ft

United States
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Since my last post I tried two more RTH attempts.

One was, again, like the OP.  Ascend over maximum height and cancel RTH.

After that I unchecked the box for Obstacle Avoidance on RTH.  The following RTH attempt was a good one.  Automagically landed at preset Home location.
2023-5-3
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fans782cd23b
lvl.1
Flight distance : 34928 ft
Bulgaria
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I had an unpleasant situation today. Believe it was caused by RTH. P4 started to ascend to the point where I lost the signal (300 m). Probably due to the low battery descended by itself. Still under investigation. Second flight - also started to ascend, but I stopped it manually. Latest firmware.

Update: Downloaded flight data. Very strange diagrams for vision_height and usonic_height. Probably low value for vision_height caused it to accelerate too high.

2023-6-1
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