With the Fly opening the scene is revealed from below for its entire width.
The mechanical system consists of a load-bearing structure, normally a truss that can be raised by means of a fly facility, which allows the curtain to rise up to completely free the proscenium.
In this way the curtain is raised as a whole, allowing the compatibility of this opening with practically all types of curtains and making.
It requires a stage height at least twice the height of the curtain.
The Fly opening system is also used for the Fire curtains, safety systems which, in the event of a fire, allow the stage to be instantly separated from the theater hall. The separation takes place by instantly lowering, adhering to the stage, a wall with adequate fire resistance characteristics.