A CRJ900 EICAS alerted diff press and the cabin pressure readout indicated red. As the emergency che...

Narrative:

Enroute at FL380 we received a differential pressure (diff press) red EICAS message and noted that the cabin pressure readout turned red. We initially donned the oxygen masks and established communication with each other. We then requested a lower altitude from center; stating that we were experiencing a pressurization issue and requesting to descend to 10;000 ft. The controller then responded clearing us to descend to FL360. The captain then responded that he was declaring an emergency and that we were descending to 10;000 ft. We then initiated the decent; I took the controls and the captain took the radios and began to run the checklist. About the same time the aircraft switched pressurization controllers automatically and the EICAS message went away and the differential pressure returned to the green range. After reading the checklist to ensure that no additional action was required we removed our masks and informed ATC that we could accept FL240 and continue to our destination. The captain also in formed them that he no longer needed emergency priority and wished to cancel the emergency declared with center. We were now talking to the next center. The captain contacted dispatch and requested fuel numbers for FL240. The flight continued normally and arrived on time in our destination. We reacted to the diff press warning indication and began the corrective action for a cabin altitude red EICAS message by donning the masks. After running the checklist we realized that a descent and donning the masks wasn't necessary. Once we realized our mistake we completed the correct checklist and contacted dispatch for new fuel numbers and completed the flight without further incident.

Original NASA ASRS Text

Title: A CRJ900 EICAS alerted DIFF PRESS and the cabin pressure readout indicated red. As the emergency checklist and descent were begun; the auto pressurization system switched controllers bringing the cabin back to normal so the emergency was undeclared and the flight continued to its destination.

Narrative: Enroute at FL380 we received a differential pressure (DIFF PRESS) red EICAS message and noted that the cabin pressure readout turned red. We initially donned the oxygen masks and established communication with each other. We then requested a lower altitude from Center; stating that we were experiencing a pressurization issue and requesting to descend to 10;000 FT. The Controller then responded clearing us to descend to FL360. The Captain then responded that he was declaring an emergency and that we were descending to 10;000 FT. We then initiated the decent; I took the controls and the Captain took the radios and began to run the checklist. About the same time the aircraft switched pressurization controllers automatically and the EICAS message went away and the differential pressure returned to the green range. After reading the checklist to ensure that no additional action was required we removed our masks and informed ATC that we could accept FL240 and continue to our destination. The Captain also in formed them that he no longer needed emergency priority and wished to cancel the emergency declared with Center. We were now talking to the next Center. The Captain contacted Dispatch and requested fuel numbers for FL240. The flight continued normally and arrived on time in our destination. We reacted to the DIFF PRESS warning indication and began the corrective action for a CABIN ALT red EICAS message by donning the masks. After running the checklist we realized that a descent and donning the masks wasn't necessary. Once we realized our mistake we completed the correct checklist and contacted Dispatch for new fuel numbers and completed the flight without further incident.

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	948604
Time
Date	201105
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Light	Daylight
Aircraft 1
Make Model Name	Regional Jet 900 (CRJ900)
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Pressurization Control System
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Commercial
Experience	Flight Crew Last 90 Days 12 Flight Crew Total 2200 Flight Crew Type 1700
Events
Anomaly	Aircraft Equipment Problem Critical

A CRJ900 EICAS alerted diff press and the cabin pressure readout indicated red. As the emergency checklist and descent were begun; the auto pressurization system switched controllers bringing the cabin back to normal so the emergency was undeclared and the flight continued to its destination.