Q400
Flight Crew Air Transport Pilot (ATP)
Distraction; Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Other / Unknown
Flight Crew Overcame Equipment Problem; Flight Crew Became Reoriented
Human Factors
Departed with cabin pressure selector in dump position.  Discovered climbing through 10;000 feet with Cabin Pressure warning. Requested descend to and maintain 10;000 from ATC and completed checklist. Problem discovered and corrected as per checklist. Remained at 10;000 for a few minutes to confirm cabin pressurizing normally and then requested higher and continued to destination. Primary cause is that my originating flow was inadequate. Contributing causes were my expectation bias; my distraction due to pride; and condition we found the aircraft in. We found the aircraft in a state in which an instructor might put a training device to check preflight and originating flows proficiency - aircraft obviously powered down without being terminated and random switches out of place. The first clue was the external nose gear safety lock protruding. I showed the First Officer (FO) how to return it to flush and secure it. Things out of place continued on the flight deck. I briefed the FO that we each needed to be extra vigilant in our pre flights and originating flows. At some point I silently congratulated myself on catching every out of place item including that we had caught what would have prevented the nose and main landing gear from retracting on takeoff. They did not get me this time. At this point; my vigilance went to zero. Climbing through 10;000 feet I discovered that they did; in fact; get me - my expectation bias; my pride leading to distraction; and the apparent failure of those having the aircraft before me to refrain from screwing with random things or to follow a checklist of any kind.
A Q400 Captain reported finding a number of switches incorrectly positioned during preflight. One was missed; resulting in the aircraft failing to pressurize during climb.