B777-200
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 166; Flight Crew Total 9821; Flight Crew Type 1238
Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; General Maintenance Action
Aircraft
At FL180 on climb out; the flight attendants called up to the cockpit to report smoke coming out of several ovens in the aft galley. I as relief pilot told the Captain that I would go back and assess the situation. When I arrived in the aft galley there in fact were several smoking ovens with real smoke. We immediately de-powered the galley and removed all food from the ovens. I called to Captain and told him that I was concerned that it was an issue different than spilled food because 6 of the 8 ovens were billowing smoke. There was no sign of spilled food or grease in any of the ovens. At that point the Captain advised ATC and made a turn to return to ZZZ for landing. I maintained coordination with the flight attendants and had them de-power all the galleys in the airplane including pulling the circuit breakers. I returned to the cockpit and took over all communications with Dispatch; the flight attendants; the passengers; and Crash Fire Rescue on the ground in ZZZ. On final approach into ZZZ the flight attendants called and said the ovens were smoking again. This was 15 minutes after power had been removed. I instructed them to shoot the ovens with the Halon extinguisher. They did and arrested the smoke. We landed without further incident. Taxied to the gate and replanned the passengers.
B777 First Officer reported that a faulty oven in the aft galley resulted in smoke and possible fire and resulted in a return to land.