Weird Render Mask Problem

[m4rtyn]

Hi there

I have rendered out a flythrough but with an object showing which I don't want to be there...

Is there a way I can use that object as a selected mask, but render whats behind it.

Eg. Rendering a sky with a plane flying across, but then removing the plane and rendering the sky behind it, but without rendering the full frame?

Hope this makes sense

Thanks