B757 Undifferentiated or Other Model
Aircraft Equipment Problem Critical
Flight Crew Diverted; General Declared Emergency; General Maintenance Action
Aircraft
[We] received cabin altitude master warning. Cabin altitude increased to 10;000; at FL360; autopilot disengaged; [we] donned masks and accomplished QRH for cabin altitude. Contacted ATC; declared emergency and initiated descent. Descending through FL260 switched auto controller 2 to auto 1; with no effect. Descending through FL200 cabin altitude began to decrease to 8;000. Diverted to a nearby airport and landed with no further issue. Maintenance found a piece of debris lodged in the over pressure valve.
Upon receipt of a cabin altitude warning a B757 flight crew declared and emergency and initiated an emergency descent. They diverted to a nearby airport where Maintenance found debris blocking the overpressure valve open.