What is the term for a rope used on an extension ladder to raise a fly section?

The term for a rope used on an extension ladder to raise a fly section is "halyard." In the context of firefighting and the use of extension ladders, the halyard serves as a critical component that allows firefighters to efficiently extend or retract the fly section of the ladder. By pulling on the halyard, personnel can elevate the fly section to reach greater heights safely and quickly, which is essential during rescue operations and when accessing elevated areas.

Understanding the function of the halyard is important for proper ladder operations, as it promotes effective use of equipment and enhances safety for firefighting personnel. Other terms listed, such as running line, hoisting sheet, and extension rope, do not specifically refer to the mechanism used for adjusting the fly section of an extension ladder. Instead, they might be relevant in different contexts or types of rigging but are not correct in the context of the question asked.