human errors that can doom a plane are no longer confined to the cockpit. Many of the most crucial ones involving the Max occurred years ago, in Boeing offices and in simulators, well before the pilots of Lion Air JT610 climbed into its cockpit. Those earlier errors included, among others, the incomprehensible design decision to allow the new flight-control system that was linked to both crashes—the Maneuvering Characteristics Augmentation System (MCAS)—to activate based on data from a single sensor, and stunningly sunny assumptions about pilot reaction time under stress.