Date: 201508
Local time of day: 0601-1200
Location: ZZZZ.ARTCC, FO
Flight conditions: VMC
Light: Daylight
Aircraft: B777 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Aircraft component: Electrical Wiring & Connectors
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Confusion; Communication Breakdown
Second reporter function: Captain; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Clearance; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Attendant
When detected: In-flight
Result: Flight Crew Overcame Equipment Problem; Flight Crew Returned To Departure Airport
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Through climb and level off the flight was normal with one exception; during climb the Cabin to Cockpit Interphone locked up. We could call the Flight Attendants (FA) and they could call us; but no conversation was possible. Our random route oceanic clearance was different than our filed route. This involved running a Supplementary Checklist. This clearance caused us to have to postpone addressing the interphone issue with our Purser. Over foreign country in level flight we completed our reroute checklist. Right after checklist completion; the FAs called the cockpit to inform us of sparks and smoke coming from Seat 1K and the seat immediately behind it. They were unable to reach us due to the interphone issue. This resulted in 10 to 15 attempts to call us (a chime sounds in the cockpit for each call attempt) in a very short period of time; less than a minute. Clearly it was evident now something was amiss. I told the Captain I'm going to get up to check the entry area to the cockpit through the viewport in the cockpit door. I told him it looks like the Purser is trying to call us. I opened the door and was told of the sparks and smoke.  The condition in the First Class (FC) cabin was such that an emergency decent and landing was not necessary. However clearly proceeding on was not an option either. We awoke the International Relief Officer (IRO) from his crew rest and he coordinated with the FAs on cabin actions for the sparks and smoke. Foreign ATC [was notified and immediate assistance was requested]. The appropriate non-normal checklists were run and dispatch and Maintenance Control were contacted. Maintenance Control instructed us to turn off power to the seats using a red guarded switch underneath the seats; Purser had already accomplished that directed action. A decision was made to return to ZZZZ as the situation was stabilized. Purser came to the cockpit to coordinate on the next steps to be taken. I was the pilot flying so the Captain was doing the coordinating with the Purser. After he was done coordinating with the Purser; we ran the Dump Fuel Checklist to be below max landing weight. Enroute back to ZZZZ electrical fumes were reported by Door 2R and additional non-normal checklists were run. Consideration was given to landing short of ZZZZ when the fumes ceased.  A normal landing was made on runway. Emergency vehicles met the aircraft and the aircraft was deemed safe to taxi to the gate. We requested Fire and Rescue to accompany us to the gate. After an uneventful landing the emergency equipment inspected the aircraft and remained with the aircraft until the cause of the sparks and smoke was determined. The cause was a loose power cable between Seat 1K and the seat behind it. The cable had become entangled in the gears on one of the electric seat foot rests. Fire; Fumes; Smoke; Cabin.


Second narrative: Through climb and level off the flight was normal with one exception; during climb the cabin to cockpit interphone locked up. They were unable to reach us due to the interphone issue. This resulted in 10 to 15 attempts to call us (a chime sounds in the cockpit for each call attempt) in a very short period of time; less than a minute. Clearly it was evident now something was amiss. In my mind I envisioned only two possibilities fire or hijacking; but which one? I instructed my First Officer to check the entry area to the cockpit through the viewport in the cockpit door. He informed me he did not see anything threatening. I told him to open the door and find out what was going on. He opened the door and we were informed of the sparks and smoke. A decision was made to return to ZZZZ as the situation was stabilized. Purser came to the cockpit to coordinate on the next steps to be taken. She did the perfect T.E.S.T. (Type; Evacuation; Special Instructions and Time for the situation at hand) inquiry of me and was clearly ahead of my decision making process. I told her what information I knew at the time; I asked her to return in 10 minutes and told her I would have the remainder of the information she required. When she returned in 10 minutes I briefed her on our return to ZZZZ the estimated time till we landed and that it would be a normal landing. Purser asked me if she could do a beverage service en-route back to ZZZZ to keep the passengers calm. It was evident to me she was in total control of the Flight Attendant (FA) crew actions. En-route back to ZZZZ; electrical fumes were reported by door 2R and additional non-normal checklists were run. Consideration was given to landing short of ZZZZ when the fumes ceased. The aircraft gross weight was reduced below the max landing weight en-route back to ZZZZ.After and uneventful landing the emergency equipment inspected the aircraft and remained with the aircraft until the cause of the sparks and smoke was determined. The cause was a loose power cable between Seat 1K and the seat behind it. The cable had become entangled in the gears on one of the electric seat foot rests.


Synopsis: With the Cockpit to Cabin Interphone locked up; a First Officer and Captain describe the initial difficulty their Flight Attendant Purser had trying to communicate with them; as sparks and smoke emanated between two First Class seats on a B777 aircraft. Captain also noted the professionalism and command by the Purser of the Flight Attendant crew actions.