A DO328 cabin attendant altitude warning alerted at 12;000 ft; so the crew completed the memory item...

Narrative:

I was PIC and pilot flying on an IFR flight plan. We were level at 12;000 ft MSL when we got a 'cabin attendant altitude' warning; which means that our cabin had not pressurized correctly. The emergency memory item for this is to descend immediately to 10;000 ft; or minimum safe altitude; and since we were only at 12;000 ft; I started a gradual descent and told my first officer to request 10;000 ft. The frequency was busy and my first officer asked for 10;000 ft and was told to standby. My first officer then asked me if we were declaring an emergency and I said no; not at this time. I did not declare at that time because we were so close to the 'safe' altitude of 10;000 ft and because I thought it was possible that ice had accumulated in the main cabin door seal while we were on the ground previously in frigid temperatures. In any case; I felt that declaring an emergency was not necessary for this particular event. I had descended almost 400 ft from 12;000 ft and at approximately 11;600 ft ATC gave us the descent to 11;000 ft and then to 10;000 ft. During this time; my first officer had used our QRH manual and had switched to manual pressurization control. At 10;000 ft we were able to pressurize and maintain a normal cabin pressure. I believe that I deviated approximately 400 ft between the time that we got the warning message and when ATC gave us the lower altitude.

Original NASA ASRS Text

Title: A DO328 CAB ALT warning alerted at 12;000 FT; so the crew completed the memory items; began a descent; got ATC clearance to 10;000 FT; and were able to regain cabin control using the Manual Mode as per the QRH.

Narrative: I was PIC and pilot flying on an IFR flight plan. We were level at 12;000 FT MSL when we got a 'CAB ALT' warning; which means that our cabin had not pressurized correctly. The emergency memory item for this is to descend immediately to 10;000 FT; or minimum safe altitude; and since we were only at 12;000 FT; I started a gradual descent and told my First Officer to request 10;000 FT. The frequency was busy and my First Officer asked for 10;000 FT and was told to standby. My First Officer then asked me if we were declaring an emergency and I said no; not at this time. I did not declare at that time because we were so close to the 'safe' altitude of 10;000 FT and because I thought it was possible that ice had accumulated in the main cabin door seal while we were on the ground previously in frigid temperatures. In any case; I felt that declaring an emergency was not necessary for this particular event. I had descended almost 400 FT from 12;000 FT and at approximately 11;600 FT ATC gave us the descent to 11;000 FT and then to 10;000 FT. During this time; my First Officer had used our QRH manual and had switched to manual pressurization control. At 10;000 FT we were able to pressurize and maintain a normal cabin pressure. I believe that I deviated approximately 400 FT between the time that we got the warning message and when ATC gave us the lower altitude.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	983532
Time
Date	201111
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Do 328 TJ (Turbojet)
Operating Under FAR Part	Part 135
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Pressurization System
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 120 Flight Crew Total 6200 Flight Crew Type 3200
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Excursion From Assigned Altitude Inflight Event / Encounter Weather / Turbulence

A DO328 cabin attendant altitude warning alerted at 12;000 ft; so the crew completed the memory items; began a descent; got ATC clearance to 10;000 ft; and were able to regain cabin control using the manual mode as per the QRH.