12.1.1.11-5 Mirror Image Layouts

Control rooms should not be designed as mirror images of each other (i.e., with the control boards of two units laid out symmetrically, side-by-side, so that one is a complete or nearly complete reversal of the other.

Additional Information: Operators who work both units have to deal with two opposite patterns of controls and displays and must reorient their expectations completely when they switch from unit to unit. This requirement violates the principle of positive transfer of training and is highly unfavorable for task performance reliability. It is also inconsistent with the guidance on consistent layout principles (see Guideline 12.1.1.2-10, “Consistency across Control Rooms.” The potential for confusion is greater when the reversal is incomplete (e.g., control boards are mirror imaged but annunciator panels are arranged identically in both units). Therefore, when mirror image control rooms exist, operational crews should be committed to one or the other unit and should not be allowed to alternate between the two mirrored units.0700