An air carrier flight crew flying a B737-200 from anc experiences an excessive cabin leak rate through the cargo door seals at FL250 resulting in an immediate descent to a lower altitude.

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Attributes
ACN	459142
Time
Date	199912
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : anc.vor
State Reference	AK
Altitude	msl single value : 25000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zan.artcc tower : mke.tower
Operator	common carrier : air carrier
Make Model Name	B737-200
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : atp
Experience	flight time last 90 days : 240 flight time total : 17000 flight time type : 8500
ASRS Report	459142
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : atp
Experience	flight time last 90 days : 200 flight time total : 13000 flight time type : 3000
ASRS Report	458202
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude other anomaly other
Independent Detector	other controllera other flight crewa other flight crewb
Resolutory Action	aircraft : equipment problem dissipated controller : issued new clearance controller : provided flight assist flight crew : overcame equipment problem
Consequence	other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Dispatched with r-hand air conditioning pack inoperative on MEL. After approximately 20 mins at FL250 (cruise altitude with pack inoperative) the altitude warning horn came on. Checked cabin altitude at 10000 ft and climbing. Donned oxygen mask and immediately tried to contact zan for lower altitude. After 2 attempts to contact ATC for lower (they were busy on at least 2 different frequencys) we started a descent in VMC. Finally got through to ATC and got lower altitude. When approximately 700 ft below assigned altitude, the use of the word 'emergency' in my initial contact with ATC may have allowed us to get a descent sooner.

Original NASA ASRS Text

Title: AN ACR FLC FLYING A B737-200 FROM ANC EXPERIENCES AN EXCESSIVE CABIN LEAK RATE THROUGH THE CARGO DOOR SEALS AT FL250 RESULTING IN AN IMMEDIATE DSCNT TO A LOWER ALT.

Narrative: DISPATCHED WITH R-HAND AIR CONDITIONING PACK INOP ON MEL. AFTER APPROX 20 MINS AT FL250 (CRUISE ALT WITH PACK INOP) THE ALT WARNING HORN CAME ON. CHKED CABIN ALT AT 10000 FT AND CLBING. DONNED OXYGEN MASK AND IMMEDIATELY TRIED TO CONTACT ZAN FOR LOWER ALT. AFTER 2 ATTEMPTS TO CONTACT ATC FOR LOWER (THEY WERE BUSY ON AT LEAST 2 DIFFERENT FREQS) WE STARTED A DSCNT IN VMC. FINALLY GOT THROUGH TO ATC AND GOT LOWER ALT. WHEN APPROX 700 FT BELOW ASSIGNED ALT, THE USE OF THE WORD 'EMER' IN MY INITIAL CONTACT WITH ATC MAY HAVE ALLOWED US TO GET A DSCNT SOONER.

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.