Date: 201209
Local time of day: 0601-1200
Location: ZZZ.ARTCC, US
Light: Daylight
Aircraft: EMB ERJ 190/195 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Pressurization Control System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Workload; Time Pressure; Training / Qualification; Situational Awareness
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Flight Crew Returned To Departure Airport; General Declared Emergency; General Maintenance Action
Contributing factors: Aircraft; Procedure
Primary problem: Aircraft

Narrative: After level off at FL300; just established at cruise; my First Officer noticed that the cabin pressure was climbing slowly through 8;500 FT. We temporary descended to FL280 to see if would stop or go down and pulled up the ECS page; everything appeared to be normal; but cabin pressure continued to climb at a slow steady rate. At that time the First Officer placed his oxygen mask on; and I proceeded to pass the flight controls to him as I went to call Dispatch on a commercial radio service. We asked for lower which we got; shortly thereafter I went ahead and put my oxygen mask on before we got the Cabin Hi warning message. Aircraft cabin continued to climb to above 10;000 FT and the Cabin Hi message appeared. At some point I ask the First Officer to declare an emergency and to get to 10;000 FT as soon as possible and to turn around and go back to the departure airport. When Dispatch answered I advised them that we had a pressurization issue with the aircraft and that we are turning back to the departure airport and to notify Maintenance Control and that I would give them a call after we landed. Before we started down or while I was waiting for Dispatch to answer the radio; I called the cabin to advised the flight attendants that we had a issue with the aircraft pressurization and that we are returning back and prepare for landing in about 25 minutes; also that I would get back to them shortly with more information. We safely got down to 10;000 FT and were cleared direct to the airport; at that point me and the First Officer removed our O2 mask. With some time to kill; I got the weather and landing data and set up for landing. I next called the cabin to get a status of themselves and the passengers; and to tell them what happened again that we are going back and how much time and that I would make a cabin announcement shortly. They told me that they were OK as well as the passengers. After my cabin announcement; I gave ATC a call and gave them and updated status that everything was OK and that we were no longer in an emergency situation; which they acknowledged. We transferred the aircraft controls back to me and we landed at the departure airport without any further problems. During my preflight of the maintenance logbook; I noticed that the day prior this aircraft had a similar incident after departing and had to return. Maintenance could not duplicate the problem and the aircraft was signed off.




Synopsis: An ERJ-190 cabin altitude exceed 10;000 FT in cruise at FL300 so an emergency was declared; the aircraft descended and returned to the departure airport where it was discovered the same anomaly occurred the previous day.