I understand that QuadPlane firmware is based on ArduPlane firmware, and that collision avoidance is available on ArduCopter. I can’t seem to find documentation if collision avoidance is available for QuadPlanes in AltHold mode.
Still, I am not sure if the quadplane firmware has the collision avoidance feature ported over.
Not quite sure if horizontal range finding is available for quadplane. it was mentioned explicitly that collision avoidance was Available for copters, but no mentions for planes.