Narrative:

Thirty minutes after takeoff the lead flight attendant called the flight deck and reported that one of the flight attendants in the aft cabin saw smoke coming from the right engine. All engine parameters were normal as well as all other aircraft systems. I spoke directly with the observing flight attendant over the interphone to get as much detail as possible. I then directed the cabin crew to locate any deadheading pilots and have them confirm the situation. Several minutes later; I got confirmation from one of our deadheading pilots that we did have a large plume of smoke/vapor coming from the engine area under the right wing. The exact area could not be determined based on restricted viewing angles from the cabin. I went back to the aft cabin to verify the severity of the smoke using normal flight deck security procedures.we contacted dispatch and maintenance control to begin developing a plan of action while still heading towards [destination]. Due to the complete unknown cause of the smoke/vapor and the fact that it was not dissipating; we all agreed to return to [departure airport] based on time to divert. Because the engine was not degraded; I elected to...just coordinate a return to [departure airport].during the return leg; the smoke/vapor stopped; this occurred about 45 minutes from the initial report from the flight attendants. We were also now at a lower altitude; fl 310 I believe. After a discussion with dispatch; we agreed to request an inspection from crash fire rescue equipment (crash fire rescue) once clear of the runway before taxiing to the gate. The return flight; approach; landing; aircraft inspection and taxi to the gate were all uneventful.when I returned to work a couple of days later; I consulted with the 787-flight standards team and had a conference call with ge engine representatives. During that conference call; the possibility of asymmetric contrails (a contrail visible on one side of the aircraft and not the other due to sun angles and shadows) was mentioned. Based on my inflight observations during the event; supplemented by the deadheading pilot's observation; I would not have made a different decision. This decision was made jointly with my first officer; dispatch and operations all in conference. However; during my follow up discussions I realize the asymmetric contrail phenomenon does provide an explanation and is noteworthy of mention across the pilot group as well as the flight operations division.

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Original NASA ASRS Text

Title: B787 flight crew reported that they returned to the departure airport after what appeared to be smoke was seen coming from the right engine.

Narrative: Thirty minutes after takeoff the lead Flight Attendant called the flight deck and reported that one of the Flight Attendants in the aft cabin saw smoke coming from the right engine. All engine parameters were normal as well as all other aircraft systems. I spoke directly with the observing Flight Attendant over the interphone to get as much detail as possible. I then directed the cabin crew to locate any deadheading pilots and have them confirm the situation. Several minutes later; I got confirmation from one of our deadheading pilots that we did have a large plume of smoke/vapor coming from the engine area under the right wing. The exact area could not be determined based on restricted viewing angles from the cabin. I went back to the aft cabin to verify the severity of the smoke using normal flight deck security procedures.We contacted Dispatch and Maintenance Control to begin developing a plan of action while still heading towards [destination]. Due to the complete unknown cause of the smoke/vapor and the fact that it was not dissipating; we all agreed to return to [departure airport] based on time to divert. Because the engine was not degraded; I elected to...just coordinate a return to [departure airport].During the return leg; the smoke/vapor stopped; this occurred about 45 minutes from the initial report from the Flight Attendants. We were also now at a lower altitude; FL 310 I believe. After a discussion with Dispatch; we agreed to request an inspection from CFR (Crash Fire Rescue) once clear of the runway before taxiing to the gate. The return flight; approach; landing; aircraft inspection and taxi to the gate were all uneventful.When I returned to work a couple of days later; I consulted with the 787-flight standards team and had a conference call with GE engine representatives. During that conference call; the possibility of asymmetric contrails (a contrail visible on one side of the aircraft and not the other due to sun angles and shadows) was mentioned. Based on my inflight observations during the event; supplemented by the deadheading pilot's observation; I would not have made a different decision. This decision was made jointly with my First Officer; Dispatch and Operations all in conference. However; during my follow up discussions I realize the asymmetric contrail phenomenon does provide an explanation and is noteworthy of mention across the pilot group as well as the flight operations division.

Data retrieved from NASA's ASRS site 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.