An airbus 320 in cruise at FL330 descended to FL230 due to a cracked captain's sliding window.

Attributes
ACN	484999
Time
Date	200009
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : hln.airport
State Reference	MT
Altitude	msl single value : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zlc.artcc
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : level
Route In Use	enroute airway : j36.airway
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : multi engine pilot : instrument pilot : flight engineer
Experience	flight time last 90 days : 150 flight time total : 19800 flight time type : 1800
ASRS Report	484999
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : multi engine pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : took precautionary avoidance action
Consequence	other other
Supplementary
Problem Areas	Environmental Factor Aircraft
Primary Problem	Aircraft

Narrative:

While cruising at FL330, the captain's sliding window developed a crack on the upper edge of window. We advised our airline dispatcher and maintenance control. We all agreed to follow the aircraft company operations manual which required a descent to FL230 and raising the cabin altitude to 8000 ft. This reduced the differential pressure to 5.0 as per airbus company operations manual. We were past our driftdown alternate required area, and the MEA that we descended into was FL200. Further discussion with airline dispatch confirmed enough fuel to meet FARS and continue to dtw at long range cruise. Landing at dtw was uneventful.

Original NASA ASRS Text

Title: AN AIRBUS 320 IN CRUISE AT FL330 DSNDED TO FL230 DUE TO A CRACKED CAPT'S SLIDING WINDOW.

Narrative: WHILE CRUISING AT FL330, THE CAPT'S SLIDING WINDOW DEVELOPED A CRACK ON THE UPPER EDGE OF WINDOW. WE ADVISED OUR AIRLINE DISPATCHER AND MAINT CTL. WE ALL AGREED TO FOLLOW THE ACFT COMPANY OPS MANUAL WHICH REQUIRED A DSCNT TO FL230 AND RAISING THE CABIN ALT TO 8000 FT. THIS REDUCED THE DIFFERENTIAL PRESSURE TO 5.0 AS PER AIRBUS COMPANY OPS MANUAL. WE WERE PAST OUR DRIFTDOWN ALTERNATE REQUIRED AREA, AND THE MEA THAT WE DSNDED INTO WAS FL200. FURTHER DISCUSSION WITH AIRLINE DISPATCH CONFIRMED ENOUGH FUEL TO MEET FARS AND CONTINUE TO DTW AT LONG RANGE CRUISE. LNDG AT DTW WAS UNEVENTFUL.

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.