When ATC failed to clear them for their requested descent to 10;000 ft; the flight crew of a B737-40...

Narrative:

Approximately 5 minutes after level off at FL330; an intermittent [cabin altitude] warning horn sounded. Qrc items were accomplished; but unable to control cabin altitude in standby. Cabin altitude [was] at approximately 11;000 ft.informed ATC of problem and requested descent to 10;000 ft and were told to stand by. We were able to see the mountain visually in the sunrise and on our terrain display well to the south; so we requested and were denied descent again.since we could observe no traffic below us on TCAS we declared an emergency and commenced emergency descent to 10;000 ft. We regained control of the cabin after leveling at 10;000 ft in manual AC mode. Flight attendants notified and reported feeling light headed. We decided to return to our departure airport where we made a normal landing.

Original NASA ASRS Text

Title: When ATC failed to clear them for their requested descent to 10;000 FT; the flight crew of a B737-400; unable to control their pressurization; declared an emergency and initiated their descent.

Narrative: Approximately 5 minutes after level off at FL330; an intermittent [cabin altitude] warning horn sounded. QRC items were accomplished; but unable to control cabin altitude in standby. Cabin altitude [was] at approximately 11;000 FT.Informed ATC of problem and requested descent to 10;000 FT and were told to stand by. We were able to see the mountain visually in the sunrise and on our terrain display well to the south; so we requested and were denied descent again.Since we could observe no traffic below us on TCAS we declared an emergency and commenced emergency descent to 10;000 FT. We regained control of the cabin after leveling at 10;000 FT in manual AC mode. Flight attendants notified and reported feeling light headed. We decided to return to our departure airport where we made a normal landing.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	986867
Time
Date	201201
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Dawn
Aircraft 1
Make Model Name	B737-400
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Pressurization System
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Critical

When ATC failed to clear them for their requested descent to 10;000 ft; the flight crew of a B737-400; unable to control their pressurization; declared an emergency and initiated their descent.