Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 138
Human-Machine Interface
Aircraft Equipment Problem Critical; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; General Declared Emergency
Aircraft; Human Factors; Procedure
The Cabin Altitude Warning horn sounded at FL330. An emergency descent was initiated and an emergency was declared. I was given direct [to our destination] and a descent to 10;000 FT. I let the aircraft descend to 9600 FT. When I checked in with approach; ATC gave me 9000 FT. A visual approach was flown to RWY 26.Prior to the Emergency Descent; we had been cleared to descend via the SID; 4000 FT was set in the Altitude window. After donning the O2 masks and starting the descent; a good cross check of the FMC and CDU should have been accomplished.
After receiving a 'descend via' clearance from ATC and setting the altitude alert at 4;000 FT per the procedure the flight crew of a B737NG received a cabin altitude warning and began an emergency descent; cleared to 10;000 FT. They failed to reset the new cleared altitude and a modest overshoot occurred before ATC recleared them to 9;000 FT.