A light on the side of a train indicating the propulsion system status is called what?

The correct answer is the propulsion fault light, which serves a specific purpose in train operations. This light is designed to provide visual feedback to the train operator regarding the status of the propulsion system. When this light is illuminated, it indicates that there is a problem or fault within the propulsion system that may affect the train's ability to operate safely and efficiently.

Understanding the significance of this indicator is crucial for train operators, as it directly impacts the operational safety and performance of the train. A failure in the propulsion system can lead to reduced power or even complete loss of movement, necessitating immediate action from the operator to assess the situation.

Other options, while they may seem relevant, do not specifically refer to the status of the propulsion system. For instance, a power check light could imply a general status of electrical power, but not specifically target propulsion issues. Similarly, a system status light and an operational indicator light may refer to multiple systems or general operational health, rather than pinpointing the specific propulsion status. Thus, the term "propulsion fault light" accurately reflects the dedicated function of indicating issues related to the propulsion system.