At what cabin altitude does the "NO SMOKING/FASTEN SEAT BELT" signs turn ON according to the CPAM sequence?

The "NO SMOKING/FASTEN SEAT BELT" signs are designed to enhance passenger safety during critical phases of flight. According to the Cabin Pressure Alerting and Monitoring (CPAM) sequence, these signs are activated at cabin altitudes of 8500 feet. This specific altitude is significant because it represents a transition point where the potential for discomfort due to changes in pressure increases, and the risk of hypoxia starts to become a concern for passengers.

At 8500 feet, cabin pressure can affect the average person, particularly those who may be sensitive to altitude changes. Therefore, activating the signs at this altitude serves to remind passengers to fasten their seatbelts and refrain from smoking, ensuring their safety and comfort as the aircraft climbs or descends through these elevations.

Higher altitudes, such as 10,000 feet or above, typically have increased restrictions; however, the immediate and critical alert starts at 8500 feet because this is where most safety protocols begin to take effect in commercial aviation.