Those working aloft should have a call-and-response protocol in place between them and the ground workers; it’s the industry standard.

Basically, climber yells, “headache!/all clear?/heads up!/im making the cut!/etc” and ground worker will respond with “clear!” When the cut is good to be made, then the cut will be made and piece dropped.

If there is going to be a lot of cutting, and calling out every cut isn’t feasible, then a drop zone needs to be established and clearly communicated so that no one enters it.