CPAM helps limit cabin altitude to which value?

CPAM helps limit cabin altitude to which value?

• A. 14,500 +/- 500 ft
• B. 15,500 +/- 500 ft
• C. 13,000 +/- 400 ft
• D. 14,000 +/- 300 ft

Answer: (A)

Limiting cabin altitude is about keeping the air inside the cabin at a safe, breathable level when the aircraft is pressurized. CPAM serves as a safety limiter in the pressurization system, constraining how high the cabin altitude can rise. It is set to about 14,500 feet, with a tolerance of roughly plus or minus 500 feet. This keeps the cabin within a breathable range long enough for the crew to diagnose and restore normal pressurization during abnormal conditions, such as a leak or outflow valve issue. The chosen value balances safety and practicality: it’s high enough to avoid unnecessary limits during normal operation, but low enough to minimize hypoxia risk and provide a clear boundary for quick corrective action. The tolerance accounts for sensor readings and system response time, so the actual cabin altitude can vary within that band without exceeding the limit.

Limiting cabin altitude is about keeping the air inside the cabin at a safe, breathable level when the aircraft is pressurized. CPAM serves as a safety limiter in the pressurization system, constraining how high the cabin altitude can rise. It is set to about 14,500 feet, with a tolerance of roughly plus or minus 500 feet. This keeps the cabin within a breathable range long enough for the crew to diagnose and restore normal pressurization during abnormal conditions, such as a leak or outflow valve issue.

The chosen value balances safety and practicality: it’s high enough to avoid unnecessary limits during normal operation, but low enough to minimize hypoxia risk and provide a clear boundary for quick corrective action. The tolerance accounts for sensor readings and system response time, so the actual cabin altitude can vary within that band without exceeding the limit.