What is the primary function of the 'fly' section of an extension ladder?

The primary function of the 'fly' section of an extension ladder is to provide a means for extension. This is the part of the ladder that slides to adjust the overall height of the ladder, allowing firefighters to reach higher areas safely. When the fly section is extended, it increases the ladder's length without requiring additional sections to be carried or deployed. This feature is essential for accessing various heights at emergency scenes, such as rooftops or upper-story windows, making it a crucial component in firefighting and rescue operations. The design of the fly section facilitates smooth extension and retraction, ensuring it can be adapted quickly to the needs of the situation.