What is the primary purpose of a halyard when used with an extension ladder?

The primary purpose of a halyard when used with an extension ladder is to hoist and lower the fly sections of an extension ladder. The halyard is a rope or cable that connects to the fly section of the ladder, allowing firefighters to extend or retract this section efficiently while maintaining control. This mechanism is vital for adjusting the ladder to the desired height and ensuring that it is properly set up for safe access to elevated locations. Understanding the function of the halyard is essential for proper ladder use and safety in firefighting operations.