Narrative:

While operating flight we were on our way up to 23000 feet as assigned to us by the [TRACON]. As we passed through about 19000 feet the cabin altitude caution message appeared on the EICAS. We stopped the climb and noticed that the cabin altitude was continuing to rise at a rapid rate. Within a few seconds we got the cabin altitude warning message on the EICAS. We then performed the memory items for cabin alt; donned the O2 masks and started an emergency descent back down to 10000 feet. We [notified] ATC (air traffic control) and told them what was happening. On the way back to 10000 feet the cabin alt reached an altitude of about 13;500 feet. When we reached 10;000 feet we finished the checklists and contacted the company via arinc (aeronautical radio incorporated). I told dispatch about our situation and they had us try the pressurization in manual mode which we did. At 10;000 feet the cabin pressure was going up and down between 4000 and 5000 feet. The captain; dispatch; and I came to the conclusion that it was best that we return back to ZZZ. We landed over weight at about 100 fpm on runway xxl and taxied to spot xx. After we shut the aircraft down and the passengers deplaned the mechanics told us that butterfly valve in the low pressure duct was stuck open and that the aircraft was able to pressurize at lower altitudes but was unable to do so as the aircraft climbed up to higher altitudes.

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Original NASA ASRS Text

Title: Flight Crew flying CRJ-900 encountered Pressurization System failure.

Narrative: While operating flight we were on our way up to 23000 feet as assigned to us by the [TRACON]. As we passed through about 19000 Feet the Cabin ALT Caution message appeared on the EICAS. We stopped the climb and noticed that the Cabin Altitude was continuing to rise at a rapid rate. Within a few seconds we got the Cabin ALT warning message on the EICAS. We then performed the memory items for Cabin Alt; donned the O2 masks and started an emergency descent back down to 10000 feet. We [notified] ATC (Air Traffic Control) and told them what was happening. On the way back to 10000 feet the cabin alt reached an altitude of about 13;500 feet. When we reached 10;000 feet we finished the checklists and contacted the company via ARINC (Aeronautical Radio Incorporated). I told Dispatch about our situation and they had us try the pressurization in manual mode which we did. At 10;000 feet the cabin pressure was going up and down between 4000 and 5000 feet. The Captain; Dispatch; and I came to the conclusion that it was best that we return back to ZZZ. We landed over weight at about 100 fpm on Runway XXL and taxied to spot XX. After we shut the aircraft down and the passengers deplaned the mechanics told us that butterfly valve in the low pressure duct was stuck open and that the aircraft was able to pressurize at lower altitudes but was unable to do so as the aircraft climbed up to higher altitudes.

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.