What is the purpose of valve position annunciators or lights?

The purpose of valve position annunciators or lights is to verify the position of the valves. These indicators provide essential information to the flight crew about the status of various control valves in the aircraft's systems. By showing whether a valve is open or closed, these lights help ensure that all systems are functioning correctly, enabling the crew to make informed decisions for safe operation.

Understanding the position of the valves is critical for managing systems like fuel flow, hydraulic operations, and environmental controls. If the crew is aware of the current status of all valves, it can help prevent malfunctions or system failures during the flight.

Additionally, other options, while relevant to cockpit functions, do not specifically pertain to the core objective of valve position annunciators. For example, illuminating the cockpit at night is a separate function linked to general visibility, signaling alarms pertains to safety alerts for failures rather than routine checks, and controlling cabin pressure is a specific operational task that does not involve verifying the state of valves. Thus, the focus of valve position annunciators is appropriately on the verification of valve positions.