Fix position setpoint update logic in Mission RTL

[msberk]

Solved Problem

Currently, when proceeding to the landing point the previous setpoint is not updated, which results in an unexpected and off course landing pattern in fixed wing.

Fixes #25436

Solution

Move position setpoint logic outside of conditional so it is applied even when it is a landing waypoint

Changelog Entry

For release notes:

Bugfix: Fix RTL logic in fixed wing RTL Mission mode that caused landing patterns to veer off of expected course

Test coverage

• See previous logs at [Bug] Fixed-wing Mission landing veers off-course in Return *Personnel Safety Risk!* #25436 for errant behavior
• See fixed log here: https://review.px4.io/plot_app?log=b9a09150-3c69-4c66-a643-0f3a491d4b14

Context

#25436

[msberk]

@sfuhrer Saw you reviewed the PR which likely introduced this behavior, if you want to see this proposed fix.

@KonradRudin interested in your feedback too

[DronecodeBot]

This pull request has been mentioned on Discussion Forum for PX4, Pixhawk, QGroundControl, MAVSDK, MAVLink. There might be relevant details there:

https://discuss.px4.io/t/px4-dev-call-sep-24-2025-team-sync-and-community-q-a/47494/1

[dagar]

I think this would need to consider other cases within handleLanding() that manipulate pos_sp_triplet->previous?

[msberk]

That may be true, but if so then mission.cpp suffers the same concern. Since mission.cpp is much more thoroughly flight tested I've gone with duplicating its approach in d3214f9 which at least accounts for the case that the wp doesn't get updated

[msberk]

New log for change to match mission.cpp logic is here: https://review.px4.io/plot_app?log=a8191432-e1bc-495d-8b38-1996cfa02cd7

[msberk]

@sfuhrer @dagar Wasn't able to make the dev call today, but wondering if there's any other comment on this. As far as I can tell this synchronizes the waypoint update logic from plain mission.cpp and fixes the bug. If this gets merged I'll make a backport PR to 1.16, as well.

[DronecodeBot]

This pull request has been mentioned on Discussion Forum for PX4, Pixhawk, QGroundControl, MAVSDK, MAVLink. There might be relevant details there:

https://discuss.px4.io/t/px4-dev-call-oct-15-2025-team-sync-and-community-q-a/47650/1