Widebody transport type aircraft at FL360 had cabin pressure rising. Aircraft started descent. So no...

Attributes
ACN	164903
Time
Date	199012
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : bke
State Reference	OR
Altitude	msl bound lower : 27000 msl bound upper : 36000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zse
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 3 Turbojet Eng
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : flight engineer pilot : instrument pilot : commercial pilot : atp
Experience	flight time last 90 days : 200 flight time total : 4000 flight time type : 750
ASRS Report	164903
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : flight engineer pilot : atp pilot : instrument
Experience	flight time last 90 days : 150 flight time total : 10000 flight time type : 500
ASRS Report	164806
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We departed pdx with marginal VFR WX (north 1000' ceiling, 42 degrees). After takeoff, I was distraction by a couple of unusual items, turning on engine anti-ice, looking up climb EPR (normally calculated on an EPR computer on other models of our widebody transport). This took me out of my normal after takeoff flow which I never returned to. Part of this flow was to turn on our other two air conditioning packs (normal takeoff is with one pack on). Passing 10000' I completed the after takeoff checklist, but somehow glossed over air-conditioning packs once again because of cabin temperature problems I was having (no doubt due to the packs being off!). Things settled down into a normal climb out, when passing FL360, the cabin altitude warning horn sounded. The cabin was passing 10000' and climbing at 500 FPM, not a rapid depressurization, but certainly not controled. I troubleshot the pressurization system, but the outflow valves were fully closed. I looked in our emergency procedures manual, but nothing addressed 'uncontrolled cabin climb.' the first officer then suggested troubleshooting the packs and I immediately discovered my omission of turning them on after takeoff. Once they were turned on, the cabin pressurization was quickly restored and we avoided dropping oxy masks which would have been very embarrassing! We had initiated a precautionary descent (approximately 2-3000 FPM), with ATC's permission and west/O causing any conflicts, which we stopped at FL270. After the cabin altitude returned below 10000' (maximum was 11500') we came off oxy and completed a normal flight. This incident taught me (or rather reinforced them) a couple of things. Under circumstances which vary at all from normal, xchk myself with extra scrutiny. Be more vigilant with cabin altitude (don't trust that it will level where I set the dial). Use the rapid depressurization checklist for any uncontrolled cabin climb (it provides a good troubleshooting guide). Everybody does dumb things occasionally.

Original NASA ASRS Text

Title: WDB TYPE ACFT AT FL360 HAD CABIN PRESSURE RISING. ACFT STARTED DESCENT. SO NOTED ONLY ONE AIR CONDITIONING PACK ON. TURNING ON OTHER TWO PACKS RESTORED CABIN PRESSURE.

Narrative: WE DEPARTED PDX WITH MARGINAL VFR WX (N 1000' CEILING, 42 DEGS). AFTER TKOF, I WAS DISTR BY A COUPLE OF UNUSUAL ITEMS, TURNING ON ENG ANTI-ICE, LOOKING UP CLB EPR (NORMALLY CALCULATED ON AN EPR COMPUTER ON OTHER MODELS OF OUR WDB). THIS TOOK ME OUT OF MY NORMAL AFTER TKOF FLOW WHICH I NEVER RETURNED TO. PART OF THIS FLOW WAS TO TURN ON OUR OTHER TWO AIR CONDITIONING PACKS (NORMAL TKOF IS WITH ONE PACK ON). PASSING 10000' I COMPLETED THE AFTER TKOF CHKLIST, BUT SOMEHOW GLOSSED OVER AIR-CONDITIONING PACKS ONCE AGAIN BECAUSE OF CABIN TEMP PROBS I WAS HAVING (NO DOUBT DUE TO THE PACKS BEING OFF!). THINGS SETTLED DOWN INTO A NORMAL CLBOUT, WHEN PASSING FL360, THE CABIN ALT WARNING HORN SOUNDED. THE CABIN WAS PASSING 10000' AND CLBING AT 500 FPM, NOT A RAPID DEPRESSURIZATION, BUT CERTAINLY NOT CTLED. I TROUBLESHOT THE PRESSURIZATION SYS, BUT THE OUTFLOW VALVES WERE FULLY CLOSED. I LOOKED IN OUR EMER PROCS MANUAL, BUT NOTHING ADDRESSED 'UNCTLED CABIN CLB.' THE F/O THEN SUGGESTED TROUBLESHOOTING THE PACKS AND I IMMEDIATELY DISCOVERED MY OMISSION OF TURNING THEM ON AFTER TKOF. ONCE THEY WERE TURNED ON, THE CABIN PRESSURIZATION WAS QUICKLY RESTORED AND WE AVOIDED DROPPING OXY MASKS WHICH WOULD HAVE BEEN VERY EMBARRASSING! WE HAD INITIATED A PRECAUTIONARY DSNT (APPROX 2-3000 FPM), WITH ATC'S PERMISSION AND W/O CAUSING ANY CONFLICTS, WHICH WE STOPPED AT FL270. AFTER THE CABIN ALT RETURNED BELOW 10000' (MAX WAS 11500') WE CAME OFF OXY AND COMPLETED A NORMAL FLT. THIS INCIDENT TAUGHT ME (OR RATHER REINFORCED THEM) A COUPLE OF THINGS. UNDER CIRCUMSTANCES WHICH VARY AT ALL FROM NORMAL, XCHK MYSELF WITH EXTRA SCRUTINY. BE MORE VIGILANT WITH CABIN ALT (DON'T TRUST THAT IT WILL LEVEL WHERE I SET THE DIAL). USE THE RAPID DEPRESSURIZATION CHKLIST FOR ANY UNCTLED CABIN CLB (IT PROVIDES A GOOD TROUBLESHOOTING GUIDE). EVERYBODY DOES DUMB THINGS OCCASIONALLY.

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.

Widebody transport type aircraft at FL360 had cabin pressure rising. Aircraft started descent. So noted only one air conditioning pack on. Turning on other two packs restored cabin pressure.