A B737 flight crew returned to the departure airport due to a cabin altitude/pressurization warning ...

Attributes
ACN	1265395
Time
Date	201505
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Component
Aircraft Component	Pressurization Control System
Person 1
Function	Captain
Experience	Flight Crew Last 90 Days 290 Flight Crew Type 10300
Events
Anomaly	Deviation - Procedural Published Material / Policy

Narrative:

Climbing through FL260; the cabin altitude warning horn sounded. We accomplished memory items and QRH for cabin altitude warning horn/abnormal pressurization. We returned to our departure airport for maintenance and to refuel. Upon rechecking the pressurization panel during descent; we discovered we had set 12;660 rather than 1;226.... I did not verify the correct altitude during the before start checklist. I should have looked more closely at the small numbers in the analog windows. I 'saw' what I was expecting to see.take time to verify every checklist item. We weren't late or rushed; but I was still lulled into responding to the checklist item as 'correct.' checklist item settings are almost always correct; but I need to ensure that I closely check every item; every time; before I respond.

Original NASA ASRS Text

Title: A B737 flight crew returned to the departure airport due to a Cabin Altitude/Pressurization warning passing through FL260. During the descent it was discovered that the wrong altitude had been set in the Pressurization Control Panel.

Narrative: Climbing through FL260; the Cabin Altitude Warning horn sounded. We accomplished memory items and QRH for Cabin Altitude Warning Horn/Abnormal Pressurization. We returned to our departure airport for Maintenance and to refuel. Upon rechecking the pressurization panel during descent; we discovered we had set 12;660 rather than 1;226.... I did not verify the correct altitude during the Before Start Checklist. I should have looked more closely at the small numbers in the analog windows. I 'saw' what I was expecting to see.Take time to verify every checklist item. We weren't late or rushed; but I was still lulled into responding to the checklist item as 'correct.' Checklist item settings are almost always correct; but I need to ensure that I closely check every item; every time; before I respond.

Data retrieved from NASA's ASRS site 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.

A B737 flight crew returned to the departure airport due to a cabin altitude/pressurization warning passing through FL260. During the descent it was discovered that the wrong altitude had been set in the pressurization control panel.