How can a Dispatcher identify a failure in the Acses system?

The correct choice indicates that a Dispatcher can identify a failure in the Acses system when the audible indicator sounds continuously after overspeed. This behavior is a clear sign of a malfunction within the system, as the audible indicator serves to alert the operator of critical issues such as overspeed conditions. If the system is functioning correctly, the audible alarm would typically sound only in the event of a legitimate safety concern, such as overspeed.

In this context, if the system continues to sound the alarm continuously, it suggests that there is a failure in the system's ability to respond appropriately to the overspeed condition, indicating that the safety features are compromised. This unresponsiveness or incorrect response is a direct reflection of system failure, which requires immediate attention from Dispatch to address the safety of ongoing operations.

The other options do not point to system failure. For instance, if the speed indicator functions normally, it suggests that the system is operating as intended. Similarly, if the system displays correct operating speeds or shows no errors, it implies normal operation without indications of a fault. Therefore, the audible indicator sounding continuously after an overspeed is a definitive sign that the system is not behaving properly, making it the correct basis for identifying a failure.