After attending a department training on fire alarm panels, the technician also went into how an elevator fire alarm system works. He mentioned one thing in particular I had never heard before, if the firefighter hat light is flashing (pictured below), the elevator should not be used. When the light is flashing, not solid, it indicates either the smoke/heat detector in the elevator shaft or control room has been activated which could indicate fire which has compromised the elevators functions. If this light is flashing, the elevator could be in an EXTREMELY hazardous state. Be aware, be vigilant.