One or more cargo doors are not closed and secure.

1. 01If pressurization is normal — door is in a safe configuration. Continue normal operation.
2. 02If pressurization is not normal: Don oxygen masks.
3. 03Establish crew communications.
4. 04Passenger signs . . . ON
5. 05If airplane has reached planned cruise altitude → step 6. If not: Do not continue the climb. Reset the FLT ALT indicator to the actual airplane altitude → step 6.
6. 06LAND ALT indicator . . . 9000 feet
7. 07If minimum safe altitude is at or below 9,000 ft → step 8; between 9,000–13,000 ft → step 10; at or above 13,000 ft → step 12.
8. 08Descend to 9,000 feet.
9. 09Maintain cabin differential pressure of 0 psi by limiting flight altitude to 9,000 ft. → step 15.
10. 10Descend to the minimum safe altitude.
11. 11LAND ALT indicator . . . Select a higher altitude (max 13,000 ft) to maintain cabin differential of 0 psi. → step 15.
12. 12Descend to the minimum safe altitude.
13. 13Pressurization mode selector . . . MAN. Use momentary actuation of the outflow valve switch to avoid large/rapid pressurization changes.
14. 14Outflow VALVE switch . . . Move to OPEN until indication shows fully open to depressurize the airplane.
15. 15Plan to land at the nearest suitable airport.
16. 16When cabin altitude is at or below 10,000 ft: oxygen masks may be removed.

• • Intermittent cabin altitude/configuration warning horn will sound and CABIN ALTITUDE lights (if installed/operative) will illuminate at approximately 10,000 ft cabin altitude.