If the CABIN PRESS LO light illuminates and cabin decompression is not rapid, when should emergency descent procedures be initiated?

If the CABIN PRESS LO light illuminates and cabin decompression is not rapid, when should emergency descent procedures be initiated?

• A. If unable to correct the problem and cabin altitude exceeds 14,000 feet
• B. Immediately
• C. When cabin altitude reaches 18,000 feet
• D. After landing

Answer: (A)

When cabin pressure is lost but the decompression isn’t rapid, you still have a window to troubleshoot while continuing to fly. The emergency descent is started when you can’t correct the pressurization problem and the cabin altitude climbs above a safe threshold. In this case, that threshold is 14,000 feet. Crossing that altitude means the risk of hypoxia increases and you need to descend to a lower, breathable altitude to reestablish a safe environment and allow time to fix the root cause. Starting descent immediately isn’t always necessary if you can regain pressurization promptly, which is why the trigger isn’t 0 feet but the point at which you can’t fix the issue and the cabin altitude exceeds 14,000 feet. Waiting until the cabin altitude reaches 18,000 feet is too late, since hypoxia risk rises as altitude increases. Descent after landing would miss the important need to ensure a safe cabin during flight.

When cabin pressure is lost but the decompression isn’t rapid, you still have a window to troubleshoot while continuing to fly. The emergency descent is started when you can’t correct the pressurization problem and the cabin altitude climbs above a safe threshold. In this case, that threshold is 14,000 feet. Crossing that altitude means the risk of hypoxia increases and you need to descend to a lower, breathable altitude to reestablish a safe environment and allow time to fix the root cause.

Starting descent immediately isn’t always necessary if you can regain pressurization promptly, which is why the trigger isn’t 0 feet but the point at which you can’t fix the issue and the cabin altitude exceeds 14,000 feet. Waiting until the cabin altitude reaches 18,000 feet is too late, since hypoxia risk rises as altitude increases. Descent after landing would miss the important need to ensure a safe cabin during flight.