Narrative:

Rapid depressurization at FL290. Departed altitude in emergency status. Approved to descend passing through FL180. Callback conversation with reporter revealed the following information: reporter stated that when the pressurization system failure began he hit the manual pressurization lock in an attempt to manually close the outflow valve. The lock would not activate. They immediately donned oxygen and began an emergency descent squawking 7700 attempting to get hold of ATC. Passing about FL190; asked if he had given them lower. He then saw the squawk. They descended to about 13000 ft when the manual handle locked and the cabin descended to about 6000 ft. He has not determined what the cause of the failure was.

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Original NASA ASRS Text

Title: A DC9 EXPERIENCED RAPID DEPRESSURIZATION. THE CREW DECLARED AN EMER AND DSNDED.

Narrative: RAPID DEPRESSURIZATION AT FL290. DEPARTED ALT IN EMER STATUS. APPROVED TO DSND PASSING THROUGH FL180. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT WHEN THE PRESSURIZATION SYS FAILURE BEGAN HE HIT THE MANUAL PRESSURIZATION LOCK IN AN ATTEMPT TO MANUALLY CLOSE THE OUTFLOW VALVE. THE LOCK WOULD NOT ACTIVATE. THEY IMMEDIATELY DONNED OXYGEN AND BEGAN AN EMER DSCNT SQUAWKING 7700 ATTEMPTING TO GET HOLD OF ATC. PASSING ABOUT FL190; ASKED IF HE HAD GIVEN THEM LOWER. HE THEN SAW THE SQUAWK. THEY DSNDED TO ABOUT 13000 FT WHEN THE MANUAL HANDLE LOCKED AND THE CABIN DSNDED TO ABOUT 6000 FT. HE HAS NOT DETERMINED WHAT THE CAUSE OF THE FAILURE WAS.

Data retrieved from NASA's ASRS site as of January 2009 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.