Date: 201809
Local time of day: 1801-2400
Location: DEN.Airport, CO
Light: Night
Aircraft: B737 Next Generation Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Aircraft component: Pressurization Control System
Component problem: Improperly Operated
Reporter function: Pilot Not Flying; First Officer
Reporter qualification: Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Human factors: Confusion; Distraction
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Overcame Equipment Problem
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: Upon landing in DEN; we had a potential bird strike. This was leg three of four; with ground time scheduled for one hour. After arrival at the gate and post flight duties; I went outside to inspect the aircraft for a bird strike which none was found. Upon returning to the flight deck; I began preparing for the next flight while the Captain was in the terminal. Since it was greater than 30 minutes to push; I couldn't complete all my preflight duties; specifically getting the ATC clearance. I then stood up in the flight deck and was just standing waiting for the Captain to return; because I wanted to take a walk as well. While standing; I continued to accomplish preflight items. I set the altitude window to 10;000 feet; which is the hold down altitude for all SIDS in DEN. I set the cabin pressurization panel flight altitude to 39;000 feet; and then inadvertently set the landing altitude to 10;000 feet instead of 1;000 feet which was the correct setting for landing at our destination. I believe this error occurred because of setting these altitudes outside my normal flows as I usually make these settings after receiving the clearance. Also; I'm usually sitting; looking up at the cabin pressurization panel not standing when making these settings. The Captain returned to the flight deck and I took a walk and returned as well. All remaining preflight duties were completed including the Before Start Check where we did not catch my error. That extra zero between 1;000 feet and 10;000 feet is about the worst combination of numbers to set incorrectly and was easily overlooked. Not saying that I was fatigued; but it was the fourth leg and starting to get dark; which may have contributed to the error. The takeoff was uneventful and during the 10;000 feet Climb Check; the cabin was pressurizing normally to the best of my recollection. However; we again didn't catch the landing altitude error. Cruise was uneventful. During our descent (mid-twenties on the altitude) the Cabin Altitude warming light illuminated and the intermittent warning horn sounded. We accomplished the memory items and requested a descent with ATC and shortly thereafter began the QRC Checklist for the Cabin Altitude Warning Horn and Light; and Emergency Descent. The mode selector was placed in Manual and the outflow valve was held in full closed. The horn stopped; and the light had gone out after about 10-15 seconds; but we continued descent to 10;000 feet; not knowing what was happening. Upon reaching 10;000 feet; we removed our masks and began investigating the problem. This is where we discovered the landing altitude was set incorrectly. I set the correct setting to 1;000 feet and we were given further step-down descents to pattern altitude. We asked for extended vectors to bring the pressurization differential and cabin altitude down and then returned the mode selector to Automatic. We then landed and taxied to the gate.Checklist discipline and VVMI procedures would have prevented this error. We read the checklist steps and verbalized the response; but need to verify response is correct for the setting.




Synopsis: B-737 First Officer reported a Cabin Altitude Warning during descent as a result of setting the wrong landing airport elevation in the cabin pressurization panel.