What system does HFD use for mutual aid with surrounding fire departments?

The Texas Intrastate Mutual Aid System (TIMAS) is the correct answer because this system is specifically designed to facilitate cooperation and resource sharing among fire departments within Texas during emergencies and disasters. TIMAS allows departments to quickly offer and request assistance when local resources are overwhelmed, ensuring a coordinated response to incidents that affect public safety.

This system is actively utilized by various fire agencies across the state, including the Houston Fire Department (HFD), to ensure that they can effectively manage resources and support each other in protecting communities.

In contrast to the other options, the Houston Mutual Aid System suggests a local framework that may not encompass the broader state-wide collaboration facilitated by TIMAS. The Texas Mutual Assistance Network might imply a statewide initiative, but it is not the designated system for firefighters. Meanwhile, the Interstate Fire Collaboration System hints at interactions with out-of-state departments, which is not the focus of HFD's mutual aid efforts. Hence, TIMAS stands out as the most relevant system for mutual aid among Texas fire departments.