Skip to content


The Flight termination failsafe action may be triggered by a safety check (e.g. RC Loss, geofence violation, etc. on any vehicle type or in any flight mode), or by the Failure Detector.

Flight termination may also be triggered from a ground station or companion computer using the MAVLink MAV_CMD_DO_FLIGHTTERMINATION command. This is sent, for example, when you call the MAVSDK Action plugin terminate() or terminate_async() methods.

When Flight termination is activated, PX4 simultaneously turns off all controllers and sets all PWM outputs to their failsafe values.

Depending on what devices are connected, the PWM failsafe outputs can be used to:

  • 展开降落伞
  • 伸展可伸缩起落架。
  • 将连接了 PWM 的云台移动到安全的方向(或将它回收)以保护摄像机。
  • 触发一个重启装置,比如安全气囊。
  • 触发警报。

PX4 不能感知接了那些安全设备 - 它只是将一组预先定义的 PWM 值用于其输出。 After triggering you should unplug the battery as soon as possible. You will need to reboot/power cycle the vehicle before it can be used again.


失效保护值被应用到终止时的所有输出。 无法配置时基触发的电机或者特定的安全设备。

:::note 这不是一个独立的 飞行终止系统。 如果断电或者自驾仪完全失控,则不会出发失效保护设备。

This is not an independent Flight Termination System. If power is lost or if the autopilot crashes completely, the failsafe devices will not be triggered.


Any safety device(s) (e.g. a parachute) that can be triggered by changing a PWM value can be used, and may be connected to any free PWM port (both MAIN and AUX).


If you're using Pixhawk-series board you will have to separately power the servo rail (i.e. from a 5V BEC, which is often also available from your ESC).


The Safety topic explains how to set the flight termination as the failsafe action to be performed for particular failsafe check.

最后,设置任意电机的 PWM_AUX_FAILn and PWM_MAIN_FAILn PWM值。

  • 通过设置 CBRK_FLIGHTTERM=0 来启用故障检测器。
  • Safety > Failure Detector > Attitude Trigger explains how to configure the attitude limits that trigger Flight termination. ::: info During takeoff excessive attitutes will trigger lockdown (kill motors, but not launch parachute) rather than flight termination. 无论 CBRK_FLIGHTTERM 为何值,此选项始终启用。 无法配置时基触发的电机或者特定的安全设备。
  • Safety > External Automatic Trigger System (ATS) explains how to configure an external trigger system.





The diagram below shows the logical flow around flight termination.

Logic diagram