The distraction of a cabin pressurization problem leads to an excursion from assigned altitude.

Attributes
ACN	480130
Time
Date	200007
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : psb.vortac
State Reference	PA
Altitude	msl bound lower : 21000 msl bound upper : 28000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zny.artcc
Operator	common carrier : air carrier
Make Model Name	DC-9 10
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : private pilot : multi engine pilot : instrument pilot : atp pilot : commercial pilot : flight engineer
Experience	flight time last 90 days : 55 flight time total : 8000 flight time type : 1600
ASRS Report	480130
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : cab alt other controllerb other flight crewb
Resolutory Action	controller : issued new clearance flight crew : declared emergency flight crew : overcame equipment problem
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

After leveling at FL280, the cabin altitude continued to climb and was up to 9200 ft. We requested a descent to FL180 and were cleared to FL270 because we had traffic ahead at FL260, which we observed visually. The captain got out the manual to handle the abnormal while the first officer flew. The first officer pointed out the cabin altitude approaching 10000 ft and we both became distraction with the problem. As we worked the problem, ARTCC asked what our altitude was, as we were passing FL260. We declared an emergency and descended to FL240 where we gained control of the pressurization. Despite some minor pressurization problems thereafter, rest of flight was uneventful. We needed to fly the airplane first. As the captain worked the abnormal, the first officer needed to fly the assigned altitude. The captain still needed to monitor the situation while he solved the problem. We both fixated on one item and lost track of the airplane.

Original NASA ASRS Text

Title: THE DISTR OF A CABIN PRESSURIZATION PROB LEADS TO AN EXCURSION FROM ASSIGNED ALT.

Narrative: AFTER LEVELING AT FL280, THE CABIN ALT CONTINUED TO CLB AND WAS UP TO 9200 FT. WE REQUESTED A DSCNT TO FL180 AND WERE CLRED TO FL270 BECAUSE WE HAD TFC AHEAD AT FL260, WHICH WE OBSERVED VISUALLY. THE CAPT GOT OUT THE MANUAL TO HANDLE THE ABNORMAL WHILE THE FO FLEW. THE FO POINTED OUT THE CABIN ALT APCHING 10000 FT AND WE BOTH BECAME DISTR WITH THE PROB. AS WE WORKED THE PROB, ARTCC ASKED WHAT OUR ALT WAS, AS WE WERE PASSING FL260. WE DECLARED AN EMER AND DSNDED TO FL240 WHERE WE GAINED CTL OF THE PRESSURIZATION. DESPITE SOME MINOR PRESSURIZATION PROBS THEREAFTER, REST OF FLT WAS UNEVENTFUL. WE NEEDED TO FLY THE AIRPLANE FIRST. AS THE CAPT WORKED THE ABNORMAL, THE FO NEEDED TO FLY THE ASSIGNED ALT. THE CAPT STILL NEEDED TO MONITOR THE SIT WHILE HE SOLVED THE PROB. WE BOTH FIXATED ON ONE ITEM AND LOST TRACK OF THE AIRPLANE.

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.