Emergency Descent

An Emergency Descent is a critical maneuver performed when the cabin pressurization system fails at high altitude, requiring the aircraft to descend as rapidly as possible to a safe breathing altitude (typically 10,000 ft or the MEA, whichever is higher).

• Crew dons oxygen masks immediately (Time of Useful Consciousness at FL350 is only 30–60 seconds)
• Thrust is reduced to idle, speed brakes are deployed fully
• The aircraft may accelerate to maximum operating speed (VMO/MMO)
• ATC is notified with a MAYDAY or PAN-PAN call
• Descent rate can exceed 6,000 ft/min
• Passenger oxygen masks deploy automatically when cabin altitude exceeds 14,000 ft
• After reaching safe altitude, crew assesses damage and decides whether to divert