What system does the interlock feature primarily protect?

The interlock feature is primarily designed to protect the stabilization system of an aerial ladder. This system ensures that the ladder is set up correctly and remains stable during operation. The interlock prevents the aerial ladder from being deployed unless certain conditions are met, such as having the stabilizers fully extended and the apparatus in a safe position. This protection is vital because an unstable platform can lead to accidents or injuries while firefighters are working at height.

In contrast, while the hydraulic system, transmission system, and aerial deployment system may all be involved in the operation of the ladder, they do not specifically require the same level of restriction and safety measures that the stabilization system does. The interlock's primary function is to ensure that stability is secured before any other operations can occur. Therefore, recognizing the role of the interlock feature in maintaining a safe working environment highlights its focus on the stabilization system.