What mode change is acceptable during motion?

The selection of "Release to MCS" as the acceptable mode change during motion is based on operational safety practices and protocols that govern train engineer actions while the train is in motion.

Transitioning from "Release" (which indicates that the system is no longer controlling the train) to "MCS" (which stands for Manual Control System) signifies that the engineer is re-engaging the manual control for train operation. This mode change is essential because it allows the engineer to gain direct control over the train when necessary and is a critical operation especially when approaching or responding to an emergency situation.

The context of this transition is particularly meaningful because it ensures the safety and responsiveness of the train under the engineer's direct authority. The change allows for necessary adjustments to speed or braking, which are crucial while the train is actively moving. Thus, the ability to switch to a manual control system while in motion aligns with the operational principles of maintaining train safety and enhancing control.

In contrast, the other modes represent transitions that either involve systems that should not be engaged while the train is moving or scenarios that could lead to unsafe operational conditions.