How to stablize Vtol (quadpane) in the air?

ArduPlane VTOL Plane
1

I am trying to stabilize a Vtol to make it stationnairebut it does not work how should I do it ?

2

Have you tried QLOITER mode?

3

To make it stationary you would need an accurate positioning system. Probably the simplest to implement is an optical flow sensor in the belly of the aircraft looking downwards.