Narrative:

During cruise flight I observed the left pack EICAS illuminate. The first officer and I accomplished the appropriate checklist. It was determined to be a left fcv shutdown of the pack and therefore could not be reclaimed. We then contacted dispatch. Since the flight was ETOPS we were concerned about going over the ocean at night with a 1 pac operation. With the concurrence of dispatch we elected to divert so maintenance could try to fix the aircraft. They had spare aircraft in order to protect passengers as well. It was also determined that an overweight landing would occur. Maintenance control was consulted and it was agreed that the overweight landing could be accomplished with minimal risk. Upon contacting approach control an emergency was declared due to the diversion and overweight landing scenario. This was accepted by ATC and a normal landing was accomplished. We then taxied to a hardstand for inspection and maintenance. After a delay for approximately 1.5 hrs we were released and continued to original destination.

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Original NASA ASRS Text

Title: B777 Captain experiences a pack failure enroute and elects to divert for maintenance prior to crossing the ocean.

Narrative: During cruise flight I observed the left pack EICAS illuminate. The First Officer and I accomplished the appropriate checklist. It was determined to be a left FCV shutdown of the pack and therefore could not be reclaimed. We then contacted Dispatch. Since the flight was ETOPS we were concerned about going over the Ocean at night with a 1 PAC operation. With the concurrence of Dispatch we elected to divert so Maintenance could try to fix the aircraft. They had spare aircraft in order to protect passengers as well. It was also determined that an overweight landing would occur. Maintenance Control was consulted and it was agreed that the overweight landing could be accomplished with minimal risk. Upon contacting Approach Control an emergency was declared due to the diversion and overweight landing scenario. This was accepted by ATC and a normal landing was accomplished. We then taxied to a hardstand for inspection and maintenance. After a delay for approximately 1.5 hrs we were released and continued to original destination.

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.