Rapid cabin pressurization loss led to emergency descent in B737-200 without clearance.

Attributes
ACN	307837
Time
Date	199506
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : anc
State Reference	AK
Altitude	msl bound lower : 10000 msl bound upper : 20000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zan
Operator	common carrier : air carrier
Make Model Name	B737-200
Operating Under FAR Part	Part 121
Flight Phase	descent other other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 10000 flight time type : 1200
ASRS Report	307837
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : flight engineer pilot : cfi pilot : atp pilot : commercial
Experience	flight time last 90 days : 200 flight time total : 14000 flight time type : 2500
ASRS Report	307828
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : declared emergency other
Consequence	other Other
Supplementary
Primary Problem	Aircraft

Narrative:

Lost cabin pressurization, cabin rate of climb indicator was pegged at plus 4000 ft. Asked ATC for lower 3 times then initiated emergency descent to 10000 ft. Never got a response from ATC. Deviated from FL200 to 10000 ft because of rapid depressurization. Callback conversation with reporter revealed the following: excessive cabin climb led flight crew to believe that they had lost part of the fuselage. An emergency descent was requested but clearance was given to similar sounding call sign ('xzz' instead of xyz'). Flight crew initiated further descent in VMC and in area of anticipated descent clearance. After the situation was under control at 10000 ft, the flight crew was unable to establish communication on last assigned frequency, so they went to approach. Flight was expedited. After landing it was discovered that a cargo door seal had blown leaving approximately a 4 inch gap. Maintenance remarked that this was a familiar problem. Reporter (monitoring pilot) stated that company's aviation psychologist followed-up on flight crew's reaction to the event -- extensive questionnaire involved. Supplemental information from acn 307828: could not notify ATC so squawked 7700.

Original NASA ASRS Text

Title: RAPID CABIN PRESSURIZATION LOSS LED TO EMER DSCNT IN B737-200 WITHOUT CLRNC.

Narrative: LOST CABIN PRESSURIZATION, CABIN RATE OF CLB INDICATOR WAS PEGGED AT PLUS 4000 FT. ASKED ATC FOR LOWER 3 TIMES THEN INITIATED EMER DSCNT TO 10000 FT. NEVER GOT A RESPONSE FROM ATC. DEVIATED FROM FL200 TO 10000 FT BECAUSE OF RAPID DEPRESSURIZATION. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: EXCESSIVE CABIN CLB LED FLC TO BELIEVE THAT THEY HAD LOST PART OF THE FUSELAGE. AN EMER DSCNT WAS REQUESTED BUT CLRNC WAS GIVEN TO SIMILAR SOUNDING CALL SIGN ('XZZ' INSTEAD OF XYZ'). FLC INITIATED FURTHER DSCNT IN VMC AND IN AREA OF ANTICIPATED DSCNT CLRNC. AFTER THE SIT WAS UNDER CTL AT 10000 FT, THE FLC WAS UNABLE TO ESTABLISH COM ON LAST ASSIGNED FREQ, SO THEY WENT TO APCH. FLT WAS EXPEDITED. AFTER LNDG IT WAS DISCOVERED THAT A CARGO DOOR SEAL HAD BLOWN LEAVING APPROX A 4 INCH GAP. MAINT REMARKED THAT THIS WAS A FAMILIAR PROB. RPTR (MONITORING PLT) STATED THAT COMPANY'S AVIATION PSYCHOLOGIST FOLLOWED-UP ON FLC'S REACTION TO THE EVENT -- EXTENSIVE QUESTIONNAIRE INVOLVED. SUPPLEMENTAL INFORMATION FROM ACN 307828: COULD NOT NOTIFY ATC SO SQUAWKED 7700.

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.