B737-300 crew landed with the cabin pressurized 2000-4000 ft below sea level.

Attributes
ACN	606778
Time
Date	200401
Day	Sun
Local Time Of Day	0001 To 0600
Place
Locale Reference	airport : cyyc.airport
State Reference	AR
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	ground : taxi
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 240 flight time total : 11200 flight time type : 6300
ASRS Report	606778
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical inflight encounter : weather inflight encounter other
Independent Detector	aircraft equipment other aircraft equipment : cabin altimeter cabin pressurization differential other flight crewa other flight crewb other other : 972
Consequence	other other
Supplementary
Problem Areas	Aircraft Weather
Primary Problem	Aircraft

Narrative:

While taxiing, approaching gate at yyc, after normal approach and landing, shut down #2 engine approximately 20 ft from gate, set parking brake, felt large pressure surge in ears. Pressure panel was in automatic, flight ground switch in ground. Looked at pressure indicator. Cabin altitude was 2000-4000 ft below sea level, off scale! (Yyc altitude 4000 ft). Immediately went to manual dc position to open the closed outflow valve that should have been open. This opened the pressure outflow valve, relieving our very distressed ears! The OAT was 35 degrees C. Maintenance action showed fault on outflow valve heater element, possibly causing failure of valve on our arrival and distress to passenger and crew. This was our 3RD leg on this plane. Was repaired overnight and was flown to den with passenger by crew next day, normally.

Original NASA ASRS Text

Title: B737-300 CREW LANDED WITH THE CABIN PRESSURIZED 2000-4000 FT BELOW SEA LEVEL.

Narrative: WHILE TAXIING, APCHING GATE AT YYC, AFTER NORMAL APCH AND LNDG, SHUT DOWN #2 ENG APPROX 20 FT FROM GATE, SET PARKING BRAKE, FELT LARGE PRESSURE SURGE IN EARS. PRESSURE PANEL WAS IN AUTO, FLT GND SWITCH IN GND. LOOKED AT PRESSURE INDICATOR. CABIN ALT WAS 2000-4000 FT BELOW SEA LEVEL, OFF SCALE! (YYC ALT 4000 FT). IMMEDIATELY WENT TO MANUAL DC POS TO OPEN THE CLOSED OUTFLOW VALVE THAT SHOULD HAVE BEEN OPEN. THIS OPENED THE PRESSURE OUTFLOW VALVE, RELIEVING OUR VERY DISTRESSED EARS! THE OAT WAS 35 DEGS C. MAINT ACTION SHOWED FAULT ON OUTFLOW VALVE HEATER ELEMENT, POSSIBLY CAUSING FAILURE OF VALVE ON OUR ARR AND DISTRESS TO PAX AND CREW. THIS WAS OUR 3RD LEG ON THIS PLANE. WAS REPAIRED OVERNIGHT AND WAS FLOWN TO DEN WITH PAX BY CREW NEXT DAY, NORMALLY.

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.