What criteria must be met for Emergency Descent Mode to be activated?

• A. Autopilot is on, altitude above 20,000 feet, and CABIN ALT CAS is displayed
• B. Autopilot is off, altitude above 30,000 feet
• C. Autopilot is on, altitude below 5,000 feet
• D. Autopilot is on, altitude above 40,000 feet, and PFD shows alarm

Answer: (A)

Emergency Descent Mode is a high-altitude safety feature that automatically commands a rapid descent to restore cabin pressure when a pressurization fault is detected. For it to engage, three conditions must be present: the autopilot is operating so the descent can be controlled, the aircraft is flying above 20,000 feet, and the CABIN ALT CAS indication is displayed, signaling a cabin altitude abnormality. When these are all true, the system takes over to descend to a safer altitude with the cabin pressure under control. If any of these conditions isn’t met—autopilot not engaged, the craft is below 20,000 feet, or there is no cabin altitude warning—the automatic activation won’t occur.