I was pressing the S1 remote control. While the plane is On the screen  show message " No Positioning (ATTI) "  

(fimeware v01.09.0200)

mmm I don't use iPad / iPhone which I suspect you have ...

But ATTI mode has GPS info but does not use it for assisting flight. If you let go the sticks - the AC will drift around influenced by air movement ... which way it was moving before letting go of sticks etc. But the GPS will still lead back to Home Point with RTH.

GPS mode - uses the GPS to assist in holding steady position in hover as well as back to Home Point.

For 99.999% of flying (if not wishing to do Follow ME, Orbit, etc) you will have S1 switch in the full up position ... GPS mode ...

Now on your photo screen shot - you have :

WARNING ... strong interference etc.

Take care as it says ... I would be inclined to move a few metres or so to see if that stops.

Nigel

I run an IPad Pro and it's exactly as Nigel states it. All the way forward with S1 is "P-Mode or GPS" (Most common), middle is "A-Mode or Atti" (GPS for RTH, map location), back is "F-Mode or Function"  (Follow Me etc.). Learning to be able to fly in Atti mode never hurts but take your time and be familiar with the controls and the bird first. Then practice in an open environment.  Also i have to say, the view from the camera in the pic doesn't look like a favorable angle ;)