Air carrier medium large transport unable to pressurize on departure. Return land.

Attributes
ACN	255005
Time
Date	199310
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : bos
State Reference	MA
Altitude	msl bound lower : 4000 msl bound upper : 4000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bos
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 200 flight time total : 10500 flight time type : 3000
ASRS Report	255005
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : less severe non adherence : published procedure
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Took off from bos in an medium large transport en route to cle. After takeoff, cabin would not pressurize. Returned to bos. Maintenance found the emergency equipment door on the bottom of the airplane wide open. This particular door light had failed. I had done the walk-around and had missed it. On subsequent walk- arounds, I noticed that you just about have to get down on your hands and knees to see that this particular door is properly secured. During taxi out, I noticed that when the aircraft was properly pressurized, the readings are so small that you can't really tell if you are pressurized or not. A contributing factor is that we do 4, 5, or sometimes even 6 walk-arounds a day. Maintaining one's vigilance can be difficult. The solution? Treat every walk-around as if it is the only walk-around you have ever done.

Original NASA ASRS Text

Title: ACR MLG UNABLE TO PRESSURIZE ON DEP. RETURN LAND.

Narrative: TOOK OFF FROM BOS IN AN MLG ENRTE TO CLE. AFTER TKOF, CABIN WOULD NOT PRESSURIZE. RETURNED TO BOS. MAINT FOUND THE EMER EQUIP DOOR ON THE BOTTOM OF THE AIRPLANE WIDE OPEN. THIS PARTICULAR DOOR LIGHT HAD FAILED. I HAD DONE THE WALK-AROUND AND HAD MISSED IT. ON SUBSEQUENT WALK- AROUNDS, I NOTICED THAT YOU JUST ABOUT HAVE TO GET DOWN ON YOUR HANDS AND KNEES TO SEE THAT THIS PARTICULAR DOOR IS PROPERLY SECURED. DURING TAXI OUT, I NOTICED THAT WHEN THE ACFT WAS PROPERLY PRESSURIZED, THE READINGS ARE SO SMALL THAT YOU CAN'T REALLY TELL IF YOU ARE PRESSURIZED OR NOT. A CONTRIBUTING FACTOR IS THAT WE DO 4, 5, OR SOMETIMES EVEN 6 WALK-AROUNDS A DAY. MAINTAINING ONE'S VIGILANCE CAN BE DIFFICULT. THE SOLUTION? TREAT EVERY WALK-AROUND AS IF IT IS THE ONLY WALK-AROUND YOU HAVE EVER DONE.

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.