Date: 201311
Local time of day: 0601-1200
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Light: Daylight
Aircraft: B757 Undifferentiated or Other Model
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: AC Generation
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Human factors: Communication Breakdown; Confusion; Training / Qualification; Troubleshooting; Workload
Anomaly: Aircraft Equipment Problem Critical
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Flight Crew Diverted; Flight Crew Landed in Emergency Condition; General Declared Emergency; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Approximately 1:15 elapsed time during flight; an electrical fault occurred. We were in cruise flight at FL350 in VMC. I was pilot flying; and during the initial electrical loss the autopilot disengaged. I took manual control of the aircraft and the Captain verified that I had control and would remain pilot flying. After confirming that the aircraft was stable and both engines operating normally; we began trying to decipher the EICAS messages and other indications to determine what exactly had happened; and agreed that the left AC system was offline. After the Captain (PM) began QRH procedures and an unsuccessful Generator Control reset. The APU was started; but auto shutdown after a fault. It was decided to begin communications with Dispatch/Maintenance and discuss our correction and/or diversion options. ACARS was now unusable; and initial attempts on Commercial Radio were unsuccessful. Eventually; contact was made between the Captain and Dispatch; and the Captain informed them of our situation and that the left engine and generator both had previous write-ups in the log book. Dispatch and Maintenance both mentioned that we were barely readable over the frequency; but the conversation was possible and ended with a mutual decision to divert to an enroute airport. Fuel balancing had been occurring due to loss of the left center pump. During this time I was flying the aircraft and using the radio with ATC. The Captain and I agreed that the next major airport was our best diversion option due to familiarity with the airport; excellent weather; and a stable descent distance that would get us close to max landing weight. We declared an emergency and intentions to divert to an enroute airport to ATC and we began our arrival. This information was communicated to the flight attendants and passengers. The pilot monitoring set up the remaining FMC and radios for a visual approach to 16. The flight deck had begun getting hot with warm airflow during the incident; and became somewhat uncomfortable during the descent. Emergency equipment was awaiting our arrival. I flew the aircraft to the landing and we exited and taxied to the gate with no other issues. We asked the emergency crew to follow us to the gate as we still had EQPT OVH indications. Upon arriving at the gate the aircraft was parked and deplaned. A fire/rescue member met us in the aircraft and informed us that they did not detect any dangerous heat signatures. Debriefings with Maintenance were completed and the aircraft released to them.  During the event I remained pilot flying and was predominantly occupied with flying the aircraft. I attempted to help in decision making scenarios and mentioning indications or other things I observed. I cannot recall missing any radio calls from ATC or any deviations from our course or altitude. All instructions from ATC were complied with; and the approach and landing seemed normal except for the absence of some indications.




Synopsis: While at cruise a B757 left generator tripped and then the APU also auto shutdown after starting; so with on a single generator an emergency was declared and the flight diverted to an enroute airport.