A flip door assembly includes a flip door and an interlock that controls whether the flip door may be opened. A worker safety system in one embodiment includes a work stand, a safety barrier, and a flip door assembly. The flip door assembly selectively engages with a keyed portion of the safety barrier to prevent access to a defined area by a worker. The flip door assembly includes a flip door having a top surface that is substantially planar to a top surface of the work stand when closed, and substantially non-planar to the top surface of the work stand when open. The flip door assembly further includes an interlock that prevents the flip door from opening when the keyed portion of the safety barrier is disengaged from the interlock, and allows the flip door to open when the keyed portion of the safety barrier is engaged with the interlock.