What must crewmembers in the engine control compartment do when a signal is called out?

When a signal is called out, crewmembers in the engine control compartment are required to call out the name of the signal as it becomes visible or audible. This procedure is crucial for maintaining safety and communication standards in railway operations. By announcing the signal, it ensures that everyone on the crew is aware of the current operating conditions and can respond appropriately to the signal indicated.

This practice of calling out the signal helps to eliminate confusion and ensures that all crewmembers are on the same page regarding the train's movements, potential actions, and any necessary precautions. It is a vital part of maintaining situational awareness and aids in preventing accidents or miscommunications that could arise from unnoticed or unacknowledged signals.

The other choices do not align with the established protocols for ensuring clear communication and operational safety among the crew. Ignoring the signal, waiting for dispatcher confirmation, or simply recording it in a logbook would compromise the immediacy and efficacy of signal recognition, negatively impacting the safety and efficiency of train operations.