What cabin altitude triggers a caution light?

A cabin altitude of 8500 ft triggers a caution light due to the increased potential for hypoxia, particularly in unpressurized aircraft or during rapid decompression scenarios. At this altitude, the atmospheric pressure decreases, leading to lower partial pressures of oxygen in the cabin. This is significant because physiological effects begin to become noticeable at altitudes above 8000 ft, making it crucial for pilots and crew to be alerted to ensure passenger safety and assess any need for supplemental oxygen. Monitoring cabin altitude and receiving caution signals allows for timely interventions that can be critical in maintaining safety in flight operations.