Hello,
I decided to share my experience what happened on my last gig - a nightmare of every sound engineer. Try yourself (hopefully without PA): first, make sure, that you have activated your IPad's screen auto rotate function. Run the Master Fader app and drag the master fader (or any other fader) button down to near zero, keep holding your finger on fader button. Now tilt down your IPad until it automatically rotates a screen 180 degrees. Release your finger and look what happens to the fader location. Cool huh? Now you can imagine what happened on this gig...