Before detaching locomotives during a 1000-mile inspection, what should be done to the cars?

Prior to detaching locomotives during a 1000-mile inspection, it is crucial to secure the cars with sufficient handbrakes. This action is essential because it ensures that the cars remain stationary while the locomotives are detached, thus preventing any unintended movement that could result in safety hazards or damage. By applying adequate handbrakes, the train's integrity is maintained, allowing for a safe and controlled inspection process.

The other options, while they may seem relevant to train handling, do not adequately address the immediate need for safety and stability during the detachment of locomotives. For example, recharging to maximum pressure would typically be part of a routine operational procedure, but it does not provide security against movement during the detachment phase. Reducing the brake pipe pressure to 10 psi may affect braking effectiveness and does not serve to securely hold the cars in place. Clearing the area for safe detachment is also important for operational safety, but it does not specifically address the need to secure the train against movement during the process. Thus, securing the cars with sufficient handbrakes is the priority in this scenario to ensure safety and compliance during inspections.