# Flight Termination Configuration The *Flight termination* [failsafe action](/px4-user-guide/config/safety.md#failsafe-actions) may be triggered by a [safety check](/px4-user-guide/config/safety.md) (e.g. RC Loss, geofence violation, etc. on any vehicle type or in any flight mode), or by the [Failure Detector](/px4-user-guide/config/safety.md#failure-detector). :::note Flight termination may also be triggered from a ground station or companion computer using the MAVLink [MAV\_CMD\_DO\_FLIGHTTERMINATION](https://mavlink.io/en/messages/common.html#MAV_CMD_DO_FLIGHTTERMINATION) command. This is sent, for example, when you call the [MAVSDK Action plugin](https://mavsdk.mavlink.io/main/en/cpp/api_reference/classmavsdk_1_1_action.html#classmavsdk_1_1_action_1a47536c4a4bc8367ccd30a92eb09781c5) `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: * Deploy a [parachute](/px4-user-guide/drone_parts/peripherals/parachute.md). * Extend retractable landing gear. * Move a PWM-connected gimbal to a safe orientation (or retract it) in order to protect the camera. * Trigger an inflatable device like an airbag. * Trigger an alarm. There is no way to recover from flight termination. 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. :::tip PX4 does not know what safety devices are attached - it just applies a predefined set of PWM values to its outputs. ::: :::tip Failsafe values are applied to all outputs on termination. There is no way to configure independent time-based (or other) triggering of the motors or specific safety devices. ::: :::note 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. ::: ## Hardware Configuration Any *safety device(s)* (e.g. a [parachute](/px4-user-guide/drone_parts/peripherals/parachute.md)) 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). :::note 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). ::: ## Software Configuration The [Safety](/px4-user-guide/config/safety.md) topic explains how to set the *flight termination* as the [failsafe action](/px4-user-guide/config/safety.md#failsafe-actions) to be performed for particular failsafe check. The [Failure Detector](/px4-user-guide/config/safety.md#failure-detector) can also (optionally) be configured to trigger flight termination if the vehicle flips (exceeds a certain attitude) or if failure is detected by an external automatic trigger system (ATS): * Enable the failure detector during flight by setting [CBRK\_FLIGHTTERM=0](/px4-user-guide/advanced_config/parameter_reference.md#CBRK_FLIGHTTERM). * [Safety > Failure Detector > Attitude Trigger](/px4-user-guide/config/safety.md#attitude-trigger) explains how to configure the attitude limits that trigger *Flight termination*. :::note During *takeoff* excessive attitutes will trigger *lockdown* (kill motors, but not launch parachute) rather than flight termination. This is always enabled, irrespective of the value of `CBRK_FLIGHTTERM`. ::: * [Safety > External Automatic Trigger System (ATS)](/px4-user-guide/config/safety.md#external-automatic-trigger-system-ats) explains how to configure an external trigger system. For each MAIN output to which a safety device is attached, where "n" is the PWM port number, set: * [PWM\_MAIN\_DISn](/px4-user-guide/advanced_config/parameter_reference.md#PWM_MAIN_DIS1) to the device's "OFF" PWM value. * [PWM\_MAIN\_FAILn](/px4-user-guide/advanced_config/parameter_reference.md#PWM_MAIN_FAIL1) to the device's "ON" PWM value. For each AUX output to which a safety device is attached, where "n" is the PWM port number, set: * [PWM\_AUX\_DIS1](/px4-user-guide/advanced_config/parameter_reference.md#PWM_AUX_DIS1) to the device's "OFF" PWM value. * [PWM\_AUX\_FAILn](/px4-user-guide/advanced_config/parameter_reference.md#PWM_AUX_FAIL1) to the device's "ON" PWM value. Finally, set the `PWM_AUX_FAILn` and `PWM_MAIN_FAILn` PWM values for any motors. ## Logic Diagram The diagram below shows the logical flow around flight termination. ![Logic diagram](/files/CUkB7Cn131VCbfEDYaZ5) --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://px4.gitbook.io/px4-user-guide/advanced_config/flight_termination.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.