QGC Guide (master)

Failsafes (PX4) ​

The Failsafes page configures what the vehicle does when it loses a link, runs low on power or detects a fault. It brings the failsafe settings that PX4 spreads across several parameter groups into one place. It is designed for PX4 1.17 or later. Older firmware shows only the settings it has.

The page only shows settings the connected vehicle has, and only the failsafes that apply to its type. For example, Quadchute is shown for VTOLs only, and GPS failure loiter for fixed wings and VTOLs. The choices, units and limits of each setting come from the vehicle's parameter metadata.

Failsafe Rows ​

Each row shows:

  • Failsafe — the name, the parameters it uses and a short description. The dot next to the name is green when the failsafe is active. It is hollow when the failsafe is turned off, for example a link loss action set to Disabled. A Warning only chip marks failsafes that only show a message and never change what the vehicle is doing.
  • Cells — one captioned cell per setting: the trigger (a timeout or threshold), the action, and any options. A colored marker next to an action shows how severe it is: warning, hold, mode fallback, return, land, or terminate/disarm. Settings that only take effect after the vehicle reboots are marked Applies after reboot. Once one is changed from the value it had when the page opened, the mark becomes a Reboot required warning. The page shows these marks instead of the reboot notice that QGroundControl shows elsewhere. Reboot from the main status indicator in the toolbar.

Some failsafes have an action that PX4 does not let you change, such as the Maximum flight time failsafe which always returns. These show the action as fixed text.

Rows are grouped by cause, with the most commonly changed settings first:

  • Return Mode — where the vehicle returns to and what it does there. Every Return action on the page uses these settings.
  • Power — battery levels and action, remaining flight time, and maximum flight time.
  • Link Loss — manual control (RC or joystick), data link (GCS), offboard and onboard computer loss.
  • Navigation & Environment — geofence, GNSS loss, position estimate loss, low position accuracy, high wind, GPS failure loiter and traffic avoidance.
  • Failsafe Behavior — how long the vehicle holds before acting, and the stick override that lets the pilot take back control.
  • VTOL — quadchute.
  • Vehicle Health — attitude failure, motor failure, imbalanced propeller, ESC arming failure, parachute, altitude loss and external trigger.

Select Active to hide the failsafes that are turned off. Changes are written to the vehicle immediately and can be made in flight.

PX4 flight termination is disabled by default and is not configured here. Until it is enabled, an attitude failure only warns the pilot once the vehicle is past its takeoff lockdown window.