Window of Circadian Low In aviation, acronyms are everywhere. But one that often slips past maintenance planners and engineers is the WOCL — the Window of Circadian Low . No , it’s not a cartoon character — it’s the time of day when the human body is least alert , and in aviation maintenance, it matters more than most realise. As regulatory reform reshapes the CASA Part 145 environment , human factors  are no longer a “tick-the-box” subject. They are fundamental to how main