The crew of an MD80 experienced loss of cabin pressure at 10000 ft during climb out.

Attributes
ACN	509900
Time
Date	200104
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : hec.vortac
State Reference	CA
Altitude	msl bound lower : 10000 msl bound upper : 13000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zla.artcc tower : ewr.tower
Operator	common carrier : air carrier
Make Model Name	MD-80 Super 80
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	climbout : vacating altitude
Route In Use	departure : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	509900
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : multi engine pilot : instrument
ASRS Report	509899
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	aircraft equipment other aircraft equipment : cabin alt.light/qrh warn. other flight crewa
Resolutory Action	controller : provided flight assist flight crew : declared emergency flight crew : landed as precaution
Consequence	other other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Aircraft

Narrative:

On initial climb out, ears popped. Asked the first officer if the cabin was pressurizing and he stated everything was normal. After passing 10000 ft, got a cabin altitude light and aural warning. Immediately leveled off at 11000 ft and informed ZLA of our problem. After running the 'unscheduled cabin climbing' checklist we got the cabin stabilized and informed ZLA that we wanted a step-climb at 13000 ft. Lost the cabin again and declared an emergency with ZLA. Ran the 'rapid depressurization' checklist and returned to lax for an uneventful landing. Supplemental information from acn 509899: on climb out from bur, aircraft appeared to pressurize normally. Passing 10000 ft (cleared to 13000 ft) we got cabin altitude light and aural warning. Captain leveled aircraft at 11000 ft. First officer told ATC we had a pressurization problem and needed to level off. Went to flow light or unscheduled climb checklist. All was normal and pressurization stabilized. Captain climbed to 13000 ft. Cabin began to climb again and light and aural warning appeared. Ran rapid depressurization checklist and got cabin to pressurize normally in manual. Suddenly cabin began another unscheduled climb, got light and aural warning. Captain declared an emergency and descended to 10000 ft. Operated pressurization in manual. Uneventful diversion to lax.

Original NASA ASRS Text

Title: THE CREW OF AN MD80 EXPERIENCED LOSS OF CABIN PRESSURE AT 10000 FT DURING CLBOUT.

Narrative: ON INITIAL CLBOUT, EARS POPPED. ASKED THE FO IF THE CABIN WAS PRESSURIZING AND HE STATED EVERYTHING WAS NORMAL. AFTER PASSING 10000 FT, GOT A CABIN ALT LIGHT AND AURAL WARNING. IMMEDIATELY LEVELED OFF AT 11000 FT AND INFORMED ZLA OF OUR PROB. AFTER RUNNING THE 'UNSCHEDULED CABIN CLBING' CHKLIST WE GOT THE CABIN STABILIZED AND INFORMED ZLA THAT WE WANTED A STEP-CLB AT 13000 FT. LOST THE CABIN AGAIN AND DECLARED AN EMER WITH ZLA. RAN THE 'RAPID DEPRESSURIZATION' CHKLIST AND RETURNED TO LAX FOR AN UNEVENTFUL LNDG. SUPPLEMENTAL INFO FROM ACN 509899: ON CLBOUT FROM BUR, ACFT APPEARED TO PRESSURIZE NORMALLY. PASSING 10000 FT (CLRED TO 13000 FT) WE GOT CABIN ALT LIGHT AND AURAL WARNING. CAPT LEVELED ACFT AT 11000 FT. FO TOLD ATC WE HAD A PRESSURIZATION PROB AND NEEDED TO LEVEL OFF. WENT TO FLOW LIGHT OR UNSCHEDULED CLB CHKLIST. ALL WAS NORMAL AND PRESSURIZATION STABILIZED. CAPT CLBED TO 13000 FT. CABIN BEGAN TO CLB AGAIN AND LIGHT AND AURAL WARNING APPEARED. RAN RAPID DEPRESSURIZATION CHKLIST AND GOT CABIN TO PRESSURIZE NORMALLY IN MANUAL. SUDDENLY CABIN BEGAN ANOTHER UNSCHEDULED CLB, GOT LIGHT AND AURAL WARNING. CAPT DECLARED AN EMER AND DSNDED TO 10000 FT. OPERATED PRESSURIZATION IN MANUAL. UNEVENTFUL DIVERSION TO LAX.

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.