Narrative:

Flight was from pdx to sjc. Aircraft was a B737-700. First officer was operating the aircraft. Flight up to climb out was normal. Altitude warning horn came on and passenger oxygen system deployed. Aircraft was at 16000 ft, cabin pressure was at 14000 ft. Caution light illuminated indicating passenger or system activated. I (captain) had just been switched to a new ATC frequency and been given climb clearance to FL230. A descent was requested and given to 10000 ft. First officer said he had cycled the engine bleed valves on troubleshooting the system, found the aircraft and pressurization switch in automatic position. Isolation valve in automatic and the engine bleeds on. Cabin was descending at 500 FPM. Flight attendants were contacted and told oxygen use was not necessary even though masks were down. PA to passenger was also made explaining situation and that oxygen use was not necessary. The pressurization system continued to operate within normal limits. I (captain) discussed passenger oxygen system with the 'a' flight attendant and was told masks were down and understood that they had not been used. The decision was made to continue to sjc. Normal climb, cruise, descent, approach and landing at sjc. I (captain) learned at cruise altitude just prior to descent that the 3 flight attendants had used their masks and that some passenger had also. If this information had been given to me at the time I first asked about the passenger oxygen system, a return to pdx would have been made. I learned lesson from poor and or incomplete information.

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Original NASA ASRS Text

Title: PAX'S OXYGEN MASKS DEPLOYED WHILE B737-700 WAS CLBING OUT THROUGH 16000 FT CAUSING THE PAX MASKS TO DEPLOY. FLC DSNDED TO 10000 FT WHILE PROB WAS FOUND TO BE MISSET PRESSURIZATION SWITCHES. FLT CONTINUED TO DEST AFTER NORMAL PRESSURIZATION WAS RE-ESTABLISHED.

Narrative: FLT WAS FROM PDX TO SJC. ACFT WAS A B737-700. FO WAS OPERATING THE ACFT. FLT UP TO CLBOUT WAS NORMAL. ALT WARNING HORN CAME ON AND PAX OXYGEN SYS DEPLOYED. ACFT WAS AT 16000 FT, CABIN PRESSURE WAS AT 14000 FT. CAUTION LIGHT ILLUMINATED INDICATING PAX OR SYS ACTIVATED. I (CAPT) HAD JUST BEEN SWITCHED TO A NEW ATC FREQ AND BEEN GIVEN CLB CLRNC TO FL230. A DSCNT WAS REQUESTED AND GIVEN TO 10000 FT. FO SAID HE HAD CYCLED THE ENG BLEED VALVES ON TROUBLESHOOTING THE SYS, FOUND THE ACFT AND PRESSURIZATION SWITCH IN AUTO POS. ISOLATION VALVE IN AUTO AND THE ENG BLEEDS ON. CABIN WAS DSNDING AT 500 FPM. FLT ATTENDANTS WERE CONTACTED AND TOLD OXYGEN USE WAS NOT NECESSARY EVEN THOUGH MASKS WERE DOWN. PA TO PAX WAS ALSO MADE EXPLAINING SIT AND THAT OXYGEN USE WAS NOT NECESSARY. THE PRESSURIZATION SYS CONTINUED TO OPERATE WITHIN NORMAL LIMITS. I (CAPT) DISCUSSED PAX OXYGEN SYS WITH THE 'A' FLT ATTENDANT AND WAS TOLD MASKS WERE DOWN AND UNDERSTOOD THAT THEY HAD NOT BEEN USED. THE DECISION WAS MADE TO CONTINUE TO SJC. NORMAL CLB, CRUISE, DSCNT, APCH AND LNDG AT SJC. I (CAPT) LEARNED AT CRUISE ALT JUST PRIOR TO DSCNT THAT THE 3 FLT ATTENDANTS HAD USED THEIR MASKS AND THAT SOME PAX HAD ALSO. IF THIS INFO HAD BEEN GIVEN TO ME AT THE TIME I FIRST ASKED ABOUT THE PAX OXYGEN SYS, A RETURN TO PDX WOULD HAVE BEEN MADE. I LEARNED LESSON FROM POOR AND OR INCOMPLETE INFO.

Data retrieved from NASA's ASRS site as of July 2007 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.