ArduCopter AltHold – motors suddenly drop to idle while hovering

ArduCopter
1

Dear developers,

I would like to ask for your help regarding an issue with my drone running Mission Planner—ArduCopter.

I was flying in Altitude Hold mode at approximately 3 meters. The drone uses DShot300 ESC protocol. Takeoff and initial climb were normal and stable.

During the flight, I played roll, pitch, and yaw, and the drone responded correctly and smoothly. After that, I released all sticks (centered throttle, roll, pitch, yaw) to let the drone hover.

After about 2–3 seconds of hovering, the motors suddenly dropped to idle speed (motors were still spinning, not disarmed), and the drone fell straight down due to gravity.

I monitored the Ground Control Station during the event, but no error or warning messages were displayed.

I’ve attached a Google Drive link showing the flight behavior, since video upload is not supported here.https://drive.google.com/file/d/1CFzN4hofKd8_HktB1QS-50gqhoQPL58S/view?usp=drivesdk

My questions are:

  1. What could cause ArduCopter in AltHold to suddenly reduce motor output to idle while still armed?

  2. Could this be related to land detection, throttle settings, or failsafe behavior?

  3. How do I deal with this issue?

Any advice or guidance would be greatly appreciated.

Thank you very much.

2

We need a .bin log. Video will not be particularly helpful, and there is an access requirement to view it, anyway.

3
  1. I have already enabled edit access for the video.
  2. Unfortunately, I did not record or save any log data during that flight.
4

Log data should still be present on the SD card. The video is not illuminating in any constructive way.

5

I didn’t enable log data as it always warming CPU CPU CPU on ground station (my other drone).

6

Then there is no way to diagnose this.

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7

You can disable all other functionalities and disable logging for unimportant parameters in this case (like pre-filter vibes) and do a test flight just to diagnose the issue.

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8

That’s probably a pretty big clue that something is wrong and a log file is even more important.

As was stated, with no log file, there’s no way to properly diagnose the problem. A parameter file might show potential issues, but won’t give the exact issue.

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