Narrative:

Climbing through 10;000 MSL right after the pm (pilot monitoring) finished the 10;000 ft climb checklist the master warning cabin pressure alarm activated. Once the alarm went off pm completed the master warning pressure checklist then requested from ATC to descend back down to 10;000 MSL to run the checklist. Once going through the checklist pm and PF (pilot flying) realized that the ground crew at lax when they towed the aircraft to and from the gate turned the pressurization switch to 'dump' and was not caught until the alarm went off alerting the crew. Once finishing the checklist and the aircraft started to pressurize as normal both crew agreed to continue as normal and requested our normal cruising altitude; with no other irregularly items occurring for the rest of the flight.the reason complacency was the number one cause of the situation was due to the fact that every take off and climb the aircraft pressurizes like it should. You get used to seeing the aircraft pressurizing and your brain could make it look like the needles are in the correct position even if they are not if you don't take a good enough look at them every time. When the crew received the aircraft many items were in the incorrect position even for an aircraft that was just towed. A statement was made that we (flight crew) should double check everything to make sure that the all the systems are set correctly; which was unfortunately not completed in the entirety leading to the master warning alarm.

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Original NASA ASRS Text

Title: The crew received a cabin pressure warning when climbing through 10;000 feet after departing LAX. After discovering that the pressurization switch was set incorrectly; they were able to proceed to their destination.

Narrative: Climbing through 10;000 MSL right after the PM (Pilot Monitoring) finished the 10;000 ft climb checklist the Master Warning Cabin Pressure alarm activated. Once the alarm went off PM completed the Master Warning Pressure checklist then requested from ATC to descend back down to 10;000 MSL to run the Checklist. Once going through the checklist PM and PF (Pilot Flying) realized that the ground crew at LAX when they towed the aircraft to and from the gate turned the pressurization switch to 'dump' and was not caught until the alarm went off alerting the crew. Once finishing the checklist and the aircraft started to pressurize as normal both crew agreed to continue as normal and requested our normal cruising altitude; with no other irregularly items occurring for the rest of the flight.The reason complacency was the number one cause of the situation was due to the fact that every take off and climb the aircraft pressurizes like it should. You get used to seeing the aircraft pressurizing and your brain could make it look like the needles are in the correct position even if they are not if you don't take a good enough look at them every time. When the crew received the aircraft many items were in the incorrect position even for an aircraft that was just towed. A statement was made that we (flight crew) should double check everything to make sure that the all the systems are set correctly; which was unfortunately not completed in the entirety leading to the Master Warning alarm.

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.