GSF advice for QuadPlane VTOL tailsitters (Yaw reset and drone flyaway)

Hi,

We have seen a couple of bad flyaway/crash incidents on our Quadplane VTOL tailsitter drone… In both cases these were preceded by ‘Emergency Yaw Reset’ messages from both EKFs.
Looking at the code, it seems that the function that produces this message will only run in the case that EK3_GSF_USE_MASK=3 - which looks to be the default.

This wiki page (Compass-less Operation — Plane documentation) suggests that GSF is mostly linked to compass-less operations, and also warns against using GSF in tailsitters.
Since we DO have a compass, I am minded to switch this to 0 - but was hoping someone could confirm that this would be sensible…
Given that we previously did 100-200 good flights with it enabled, I am always a little wary to suddenly change something like this :-).

And if it is advised to disable GSF on tailsitters, I wonder if tailsitter.cpp should override the default for this, to aid others in the future avoid the mistake?

Simon.