MD80 flight crew has an oxygen malfunction during cruise.

Attributes
ACN	699428
Time
Date	200606
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : zhu.artcc
State Reference	TX
Altitude	msl single value : 32000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zhu.artcc
Operator	common carrier : air carrier
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	699428
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : o2 indicator other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : landed as precaution
Consequence	other
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Aircraft

Narrative:

Crew oxygen bottle pressure was normal during postflt inspection previous night and during origination preflight including oxygen mask/regulator checks prior to flight. During cruise; heard a hissing sound from area of captain's oxygen mask. Captain checked mask and regulator thoroughly; sound did not change and there was no detectable leak. Later noted that bottle pressure was at or near 0. Diverted to msy to investigate leak and replenish bottle. As ATC was able to provide immediate descent upon diversion request; no emergency authority/authorized was exercised and no emergency was declared with ATC.

Original NASA ASRS Text

Title: MD80 FLT CREW HAS AN OXYGEN MALFUNCTION DURING CRUISE.

Narrative: CREW OXYGEN BOTTLE PRESSURE WAS NORMAL DURING POSTFLT INSPECTION PREVIOUS NIGHT AND DURING ORIGINATION PREFLT INCLUDING OXYGEN MASK/REGULATOR CHKS PRIOR TO FLT. DURING CRUISE; HEARD A HISSING SOUND FROM AREA OF CAPT'S OXYGEN MASK. CAPT CHKED MASK AND REGULATOR THOROUGHLY; SOUND DID NOT CHANGE AND THERE WAS NO DETECTABLE LEAK. LATER NOTED THAT BOTTLE PRESSURE WAS AT OR NEAR 0. DIVERTED TO MSY TO INVESTIGATE LEAK AND REPLENISH BOTTLE. AS ATC WAS ABLE TO PROVIDE IMMEDIATE DSCNT UPON DIVERSION REQUEST; NO EMER AUTH WAS EXERCISED AND NO EMER WAS DECLARED WITH ATC.

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.