A B737-400 cabin altitude warning horn sounded at FL330. The crew began an emergency descent and div...

Attributes
ACN	708100
Time
Date	200608
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zzz.artcc
Operator	common carrier : air carrier
Make Model Name	B737-400
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
Experience	flight time type : 3500
ASRS Report	708100
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : cabin alt warning horn other flight crewa
Resolutory Action	flight crew : diverted to another airport flight crew : overcame equipment problem
Consequence	other
Supplementary
Problem Areas	Aircraft Maintenance Human Performance
Primary Problem	Aircraft

Narrative:

We had just leveled off at FL330 on our way to ZZZ2 on a flight out of ZZZ1. We were at or close to abc intersection on flight plan route. We then got the cabin altitude warning horn; and I saw the cabin altitude was at 10000 ft and the rate of climb was 1000 ft per minute. We donned our oxygen masks and established communications. I asked the first officer to ask ATC for lower and divert to ZZZ3. We then proceeded with the qrc; QRH procedures and emergency descent procedures and a diversion to ZZZ3. Once the first officer completed the items required on checklists and we had gotten to a lower altitude; he asked the flight attendants if any passenger or crew was having discomfort from the descent. Only one passenger complained of any problems. We accomplished the descent and approach checks were vectored for the ILS to runway 34R and landed uneventfully. The emts met aircraft at gate and gave assistance to any passenger that requested it. From what I was told this is a repeat problem with the aircraft. What needs to be done is for maintenance to find the problem and correct it. And if this means taking it out of service till that happens; so be it.

Original NASA ASRS Text

Title: A B737-400 CABIN ALT WARNING HORN SOUNDED AT FL330. THE CREW BEGAN AN EMER DSCNT AND DIVERTED.

Narrative: WE HAD JUST LEVELED OFF AT FL330 ON OUR WAY TO ZZZ2 ON A FLT OUT OF ZZZ1. WE WERE AT OR CLOSE TO ABC INTXN ON FLT PLAN RTE. WE THEN GOT THE CABIN ALT WARNING HORN; AND I SAW THE CABIN ALT WAS AT 10000 FT AND THE RATE OF CLB WAS 1000 FT PER MINUTE. WE DONNED OUR OXYGEN MASKS AND ESTABLISHED COMMUNICATIONS. I ASKED THE FO TO ASK ATC FOR LOWER AND DIVERT TO ZZZ3. WE THEN PROCEEDED WITH THE QRC; QRH PROCS AND EMER DSCNT PROCS AND A DIVERSION TO ZZZ3. ONCE THE FO COMPLETED THE ITEMS REQUIRED ON CHKLISTS AND WE HAD GOTTEN TO A LOWER ALT; HE ASKED THE FLT ATTENDANTS IF ANY PAX OR CREW WAS HAVING DISCOMFORT FROM THE DSCNT. ONLY ONE PAX COMPLAINED OF ANY PROBS. WE ACCOMPLISHED THE DSCNT AND APCH CHKS WERE VECTORED FOR THE ILS TO RWY 34R AND LANDED UNEVENTFULLY. THE EMTS MET ACFT AT GATE AND GAVE ASSISTANCE TO ANY PAX THAT REQUESTED IT. FROM WHAT I WAS TOLD THIS IS A REPEAT PROB WITH THE ACFT. WHAT NEEDS TO BE DONE IS FOR MAINT TO FIND THE PROB AND CORRECT IT. AND IF THIS MEANS TAKING IT OUT OF SVC TILL THAT HAPPENS; SO BE IT.

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.

A B737-400 cabin altitude warning horn sounded at FL330. The crew began an emergency descent and diverted.