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Failsafe

The Failsafe tab configures how the flight controller detects a lost radio link and what to do with each channel once it has -- the front end of failsafe. What the aircraft actually does next (glide to a landing or cut the motor) is a firmware-level choice (failsafe_procedure) that isn't exposed as a GUI control yet -- see below for how to check/change it from the CLI.

Configure and bench-test failsafe behavior before flying -- turn off your transmitter at a safe distance from the aircraft (props off) and confirm the flight controller actually enters failsafe and behaves the way you expect.

Note

If a Backup RX Input is configured, losing the main link doesn't reach any of the stages below on its own -- control switches to the backup receiver instead, within the main receiver's own ~100ms signal-loss detection window. The staged failsafe behavior described on this page only takes over if both the main link and the backup link are down.

Pulse Width Limit

Sets the valid pulse-width range (default 885-2115μs, expert mode only) -- any channel reporting a value outside it is treated as failed and enters failsafe individually, which is what actually feeds the per-channel Channel Fallback behavior below and the overall link-loss detection.

Channel Fallback

Per-channel behavior once that channel is judged failed:

  • Auto drives it to a safe value automatically -- center for Roll, Pitch, Yaw; low for Throttle.
  • Hold freezes it at its last known-good position.
  • Set drives it to a specific value you choose.

What happens next (CLI)

Once RX data has been invalid for failsafe_delay (default 15, in tenths of a second -- 1.5s), the firmware runs whichever failsafe_procedure is configured: DROP (cut output immediately -- the default) or AUTO-LAND (attempt a controlled glide down). For AUTO-LAND, failsafe_off_delay (default 10, 1s) then bounds how long the landing phase runs before motors are finally cut. All of these are CLI settings (failsafe_procedure, failsafe_delay, failsafe_off_delay) -- worth checking and bench-testing even though there's no dedicated tab for them yet.