# Aircraft moved upwards under low throttle

**URL:** <https://discuss.px4.io/t/aircraft-moved-upwards-under-low-throttle/48239>\
**Category:** Pixhawk\
**Created:** [January 5, 2026, 3:26pm UTC](https://discuss.px4.io/t/aircraft-moved-upwards-under-low-throttle/48239 "2026-01-05T15:26:30Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![S\_M](https://discuss.px4.io/user_avatar/discuss.px4.io/s_m/32/19624_2.png) [@S\_M](https://discuss.px4.io/u/S_M)\
**Post date:** [January 5, 2026, 3:26pm UTC](https://discuss.px4.io/t/aircraft-moved-upwards-under-low-throttle/48239/1 "2026-01-05T15:26:30Z")

</div>

Guys, I’m new to PX4 community and I recently experienced a crash with my custom-built aircraft and noticed a very unusual behavior during the flight. Specifically, when I reduced the throttle using Position Mode, the aircraft continued to climb instead of descending as expected. I had to switch to Stabilized Mode to lower the height of the UAV, then it came totally uncontrollable leading to final crash. Here are some flight reviews I have found: [https://review.px4.io/plot\_app?log=742b97f8-91ef-49ae-a092-5e84a3e4ed54](https://review.px4.io/plot_app?log=742b97f8-91ef-49ae-a092-5e84a3e4ed54). Has anyone encountered similar behavior in PX4? Any insights or debugging tips would be highly appreciated. Thanks for ur replies!!!

---

<div class="post-metadata">

**Author:** ![S\_M](https://discuss.px4.io/user_avatar/discuss.px4.io/s_m/32/19624_2.png) [@S\_M](https://discuss.px4.io/u/S_M)\
**Post date:** [January 6, 2026, 5:14am UTC](https://discuss.px4.io/t/aircraft-moved-upwards-under-low-throttle/48239/2 "2026-01-06T05:14:35Z")

</div>

At the moment when the aircraft starts climbing aggressively,  
the position Z setpoint disappears from the plot.

 ![bokeh_plot](https://discuss.px4.io/uploads/default/original/3X/c/c/cc5ce048734abfc0a17a6a1a8dc21cdbc8dc3dbe.png)

---

<div class="post-metadata">

**Author:** ![S\_M](https://discuss.px4.io/user_avatar/discuss.px4.io/s_m/32/19624_2.png) [@S\_M](https://discuss.px4.io/u/S_M)\
**Post date:** [January 6, 2026, 5:40am UTC](https://discuss.px4.io/t/aircraft-moved-upwards-under-low-throttle/48239/3 "2026-01-06T05:40:26Z")

</div>

Before the aggressive climb starts, the system reports  
**‘High accelerometer bias’**.  
Shortly after that, the **position Z setpoint disappears** from the log.  
This suggests that the EKF no longer trusted the IMU,  
the vertical position estimate became invalid,  
and the position controller lost its Z setpoint and fell back  
to a thrust-based behavior, which explains why reducing throttle  
did not stop the climb.

---

<div class="post-metadata">

**Author:** ![system](https://discuss.px4.io/uploads/default/original/3X/7/3/73ce918bdcd64854de904f0c8d9ab70ca9723f2a.png) [@system](https://discuss.px4.io/u/system)\
**Post date:** [April 7, 2026, 10:01am UTC](https://discuss.px4.io/t/aircraft-moved-upwards-under-low-throttle/48239/5 "2026-04-07T10:01:11Z")

</div>

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.