Narrative:

Shortly after takeoff; a flight attendant called the cockpit to report a smoke/burning smell. I did not smell it; but my first officer did smell it faintly and described it as a sweet burning smell. I sent the relief pilot to the cabin to investigate. He reported back to me that yes he did smell a faint odor but it was going away. He interviewed some of the passengers and the consensus was a sweet burning smell. After he returned to the cockpit I went to the cabin to do my own investigation. I smelled nothing out of the ordinary during my time in the cabin. Some of the passengers I interviewed claimed that the smell had come in waves; others said that the smell was gone. In absence of any current unusual smells I decided to continue the flight. I instructed the flight attendants to periodically monitor the cabin and many of the passengers assured me they would get a message to me if the smell came back. Just under an hour into the flight I and my first officer saw and smelled heavy smoke in the cockpit. We immediately donned our oxygen masks and I declared an emergency along with my intentions to divert immediately. Shortly into our diversion the smoke began to subside and approximately five minutes later we noticed the EICAS displayed a right reirc fan message. As this was going to be an overweight landing and my first officer was low time in the aircraft; I assumed pilot flying duties. As we flew the smoke subsided and we removed our oxygen masks. I began getting a slight headache and decided to stay on oxygen for the remainder of the flight. I performed an uneventful overweight landing. The cause of the first smoke smell remains a mystery. The second smoke smell was most likely caused by the burning up of the right recirculation fan.

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Original NASA ASRS Text

Title: B767 Captain is informed of a sweet burning smell in the cabin shortly after takeoff. The smell is very faint and quickly dissipates. One hour into the flight more vigorous smoke is detected in the cockpit and the flight diverts to the nearest suitable airport. The smoke began to subside and approximately five minutes later the EICAS displayed a RIGHT REIRC FAN message.

Narrative: Shortly after takeoff; a Flight Attendant called the cockpit to report a smoke/burning smell. I did not smell it; but my First Officer did smell it faintly and described it as a sweet burning smell. I sent the Relief Pilot to the cabin to investigate. He reported back to me that yes he did smell a faint odor but it was going away. He interviewed some of the passengers and the consensus was a sweet burning smell. After he returned to the cockpit I went to the cabin to do my own investigation. I smelled nothing out of the ordinary during my time in the cabin. Some of the passengers I interviewed claimed that the smell had come in waves; others said that the smell was gone. In absence of any current unusual smells I decided to continue the flight. I instructed the flight attendants to periodically monitor the cabin and many of the passengers assured me they would get a message to me if the smell came back. Just under an hour into the flight I and my First Officer saw and smelled heavy smoke in the cockpit. We immediately donned our oxygen masks and I declared an emergency along with my intentions to divert immediately. Shortly into our diversion the smoke began to subside and approximately five minutes later we noticed the EICAS displayed a RIGHT REIRC FAN message. As this was going to be an overweight landing and my First Officer was low time in the aircraft; I assumed pilot flying duties. As we flew the smoke subsided and we removed our oxygen masks. I began getting a slight headache and decided to stay on oxygen for the remainder of the flight. I performed an uneventful overweight landing. The cause of the first smoke smell remains a mystery. The second smoke smell was most likely caused by the burning up of the right recirculation fan.

Data retrieved from NASA's ASRS site as of July 2013 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.