Almost crash during landing due to RTL on Q_plane (again)

Hello there,

Once again I was very close to crash my Vtol plane due to AP switched to RTL while it was in Q_loiter at very low altitude.

Please check attached log and setting file.

I hope there is a parameter to set but I’m unable to find it otherwise we need to have a parameter to setup the minimum altitude in which the system is allowed to switch from -previous mode- into RTL with conversion.

Hawk VTOL AP4.2.1 15-07-2022.param (20.6 KB)

Log file : 15-07-2022 - Google Drive

no one has found the same issue?? how do you cover this case?

this has been reported a couple of times but currently no proper fix

maybe @tridge can help?

The devs don’t consider this to be an issue. The workaround is Q_RTL_MODE = 1, but it comes with drawbacks.

I would love to hear explanation why this is NOT a safety issue.

Currently battery failsafe is completely unusable and dangerous for vtol operators.


I’m glad that I’m not the only one sharing concerns about

It’s definitely a safety issue and appears to be unmitigated with the default parameters (Q_RTL_MODE = 0 by default). This is the best explanation I got: Quadplane: Battery Failsafe in Q modes causes transition to fixed-wing RTL. · Issue #17617 · ArduPilot/ardupilot · GitHub

The workaround of Q_RTL_MODE = 1 works, but only if you only operate in VTOL modes within the the radius that QRTL uses. Maybe rally points would be a suitable workaround for VTOL operation away from the home location?

Other discussions of this issue:

This has been finally fix with latest update Plane 4.3 stable release - ArduPlane / Plane 4.3 - ArduPilot Discourse

I don’t think so, it looks like it still requires

Q_RTL_MODE=3 (approach)