B737-300 flight crew in cruise at FL290, made an emergency descent and diverted due to an altitude w...

Attributes
ACN	530305
Time
Date	200111
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 29000
Environment
Flight Conditions	VMC
Aircraft 1
Controlling Facilities	artcc : zny.artcc
Operator	common carrier : air carrier
Make Model Name	B737-300
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
Qualification	pilot : atp
Experience	flight time last 90 days : 140 flight time total : 16000 flight time type : 11000
ASRS Report	530305
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : alt warning horn
Resolutory Action	flight crew : declared emergency flight crew : overcame equipment problem
Consequence	other other
Supplementary
Problem Areas	Aircraft Cabin Crew Human Performance Flight Crew Human Performance
Primary Problem	Aircraft

Narrative:

Cruise FL290 from XXX-XXX the altitude warning horn sounded and cabin altitude read 10500 ft and increasing. Oxygen masks were put on and checklist run. Cabin altitude was approaching 14000 ft, so I turned on passenger oxygen, emergency declared and descent begun. Emergency was declared to ensure traffic separation on descent. No aircraft were in our vicinity on descent. The depressurization was gradual and was not felt (ears or hypoxia symptoms). Flight attendants initially thought oxygen masks dropping was inadvertent, but I informed them to use the masks after leveling at 10000 ft, it appeared we gained control of the cabin pressurization. Dispatch was very difficult to patch through company radio. They said to proceed to mht. Emergency descent was smooth and controled. Landing was uneventful and there were no injuries or complaints from customers. The reason for filing this report was in case ATC had any problems or complaints with us asking for the emergency descent of which none were stated during the event. Crew overnighted in mht as scheduled and no cause for the depressurization had been determined when we left for the hotel.

Original NASA ASRS Text

Title: B737-300 FLT CREW IN CRUISE AT FL290, MADE AN EMER DSCNT AND DIVERTED DUE TO AN ALT WARNING HORN AND CAB ALT CLIMBING TO 14000 FT.

Narrative: CRUISE FL290 FROM XXX-XXX THE ALT WARNING HORN SOUNDED AND CABIN ALT READ 10500 FT AND INCREASING. OXYGEN MASKS WERE PUT ON AND CHKLIST RUN. CABIN ALT WAS APCHING 14000 FT, SO I TURNED ON PAX OXYGEN, EMER DECLARED AND DSCNT BEGUN. EMER WAS DECLARED TO ENSURE TFC SEPARATION ON DSCNT. NO ACFT WERE IN OUR VICINITY ON DSCNT. THE DEPRESSURIZATION WAS GRADUAL AND WAS NOT FELT (EARS OR HYPOXIA SYMPTOMS). FLT ATTENDANTS INITIALLY THOUGHT OXYGEN MASKS DROPPING WAS INADVERTENT, BUT I INFORMED THEM TO USE THE MASKS AFTER LEVELING AT 10000 FT, IT APPEARED WE GAINED CTL OF THE CABIN PRESSURIZATION. DISPATCH WAS VERY DIFFICULT TO PATCH THROUGH COMPANY RADIO. THEY SAID TO PROCEED TO MHT. EMER DSCNT WAS SMOOTH AND CTLED. LNDG WAS UNEVENTFUL AND THERE WERE NO INJURIES OR COMPLAINTS FROM CUSTOMERS. THE REASON FOR FILING THIS RPT WAS IN CASE ATC HAD ANY PROBS OR COMPLAINTS WITH US ASKING FOR THE EMER DSCNT OF WHICH NONE WERE STATED DURING THE EVENT. CREW OVERNIGHTED IN MHT AS SCHEDULED AND NO CAUSE FOR THE DEPRESSURIZATION HAD BEEN DETERMINED WHEN WE LEFT FOR THE HOTEL.

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.

B737-300 flight crew in cruise at FL290, made an emergency descent and diverted due to an altitude warning horn and cabin attendant altitude climbing to 14000 ft.