Narrative:

While in cruise at FL340; the aircraft began to depressurize. I heard a thump that could have been the flight attendant (flight attendant) in the galley cabinets but I am not 100% positive because; within seconds of the noise; I felt my ears start to pop. I immediately looked at the EICAS; noted that the cabin altitude had started to climb slowly from the 7;000s; and then began flashing amber; the psi differential went to 8.9. I immediately informed the captain of the situation. There were no warning messages; caution messages; crew awareness messages; or oral alerts during the entire event.cause of depressurization is unknown. The captain called ATC and requested a lower altitude. I continued to monitor the cabin altitude and informed him that it was continuing to climb and now flashing red as the cabin passed through 10;000. The captain called for the QRH; and we donned masks and established communication. The captain communicated the emergency with ATC; and we began a descent to 10;000. The cabin continued to rise to just over 15;000 and then stabilized. We informed the flight attendant of the situation; and she updated us that the cabin masks had deployed. Once level at 10;000 we removed our masks and conducted our descent checklists and briefs for arrival. The captain updated the flight attendant and the passengers; additionally; he notified ATC we did not require assistance upon landing. During the approach phase of flight; the captain and I both remarked how hot it was even though both packs were set to the usual position for cabin temperature. We landed without further issue and parked at our gate.

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Original NASA ASRS Text

Title: EMB-145 First Officer reported a failure of the pressurization system; which resulted in a slow deterioration of aircraft cabin pressure. A subsequent successful landing at the destination airport was accomplished.

Narrative: While in Cruise at FL340; the aircraft began to depressurize. I heard a thump that could have been the Flight Attendant (FA) in the galley cabinets but I am not 100% positive because; within seconds of the noise; I felt my ears start to pop. I immediately looked at the EICAS; noted that the cabin altitude had started to climb slowly from the 7;000s; and then began flashing Amber; the PSI differential went to 8.9. I immediately informed the Captain of the situation. There were no Warning Messages; Caution Messages; Crew Awareness Messages; or Oral Alerts during the entire event.Cause of depressurization is unknown. The Captain called ATC and requested a lower altitude. I continued to monitor the Cabin Altitude and informed him that it was continuing to climb and now flashing red as the Cabin passed through 10;000. The captain called for the QRH; and we donned masks and established communication. The Captain communicated the emergency with ATC; and we began a descent to 10;000. The cabin continued to rise to just over 15;000 and then stabilized. We informed the Flight Attendant of the situation; and she updated us that the cabin masks had deployed. Once Level at 10;000 we removed our masks and conducted our descent checklists and briefs for arrival. The Captain updated the FA and the passengers; additionally; he notified ATC we did not require assistance upon landing. During the approach phase of flight; the Captain and I both remarked how hot it was even though both Packs were set to the usual position for cabin temperature. We landed without further issue and parked at our gate.

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.