B757-200
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Overcame Equipment Problem; General Declared Emergency
Aircraft
During cruise flight at FL380; we received a 'Cabin Altitude' EICAS alert accompanied by a warning horn. We confirmed the cabin altitude was slightly above 10;000 MSL and showing an extremely slow rate of climb (less than 200 FPM). In addition the cabin differential pressure was extremely low for the altitude we were at. We then donned our O2 masks. The Captain declared an emergency with ATC and I began an emergency descent out of FL380. During the descent the Captain managed to control the Cabin rate of climb by switching from 'Auto Controller #2' to 'Manual' and later by switching to 'Auto Controller #1'. Once the Pressurization system had been switched over to another Auto Controller and was reacting normally; we decided to halt our descent at FL300. The Cabin continued to descend to the normal Cabin Altitude and differential pressure began to increase to a normal level for FL300. We decided that continued flight was possible and informed ATC that we would cancel the emergency and continue to our destination. The rest of the flight proceeded normally and we landed without incident.
[Narrative 2 contained no additional information.]
The flight crew of a B757-200 began an emergency descent when they received a cabin altitude warning at FL380. When the Captain stabilized the system by selecting an alternate pressure controller they canceled the emergency and continued to their destination at FL300.