Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Deviation - Speed All Types; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Air Traffic Control Issued New Clearance; Flight Crew Landed in Emergency Condition
Shortly after reaching initial cruise altitude the Captain and I noticed a burning smell. Almost immediately we received a call from the flight attendant that there was smoke in the cabin. I was the pilot flying and continued to fly while the Captain spoke with the flight attendant. The Relief Pilot (FB) was on break in the cabin and helped locate the source of the smoke which was from a business class seat. While he was doing that; I initiated a course to return directly to [departure airport] and began descent for landing. We ran the 'Smoke and Fumes'; 'Emergency Landing;' and 'Overweight Landing' checklists and checked the landing legality charts. I gave our information to ATC and the Captain informed Dispatch through Ramp Control. I exceeded 250 KIAS below 10;000 feet to expedite out arrival. I went on oxygen for a short time out of an abundance of caution. About midway through our descent the smell began to dissipate. We performed an uneventful landing and taxied to the gate.
[Report narrative contained no additional information]
Upon reaching cruise altitude; flight crew smelled fumes and received call from Flight Attendant alerting them to smoke in the cabin. Crew performed Smoke and Fumes Checklist and returned to departure airport.