Narrative:

We departed sea runway 34C in clear weather. [A] 737-800 had preceded us on departure. First officer; hand-flying; with LNAV and VNAV selected on the MCP; MOUNTAIN6 departure. SID calls for over flying nezug and then a turn right to a heading of 070; about 2 miles prior to nezug; at 5;000 ft; we [experienced] a wake turbulence upset; which caused nearly 30 degrees of right bank. First officer appeared to react properly; as the bank angle initially came back to about 20 degrees of right bank; but the turbulence continued. The bank angle then varied between 20 to 25 degrees of right bank. I was focused on the aircraft attitude; and was concerned that the first officer was having trouble leveling the wings; so I asked him; 'are you able to level the wings?' I was about to take control of the aircraft. I didn't hear him answer; as ATC directed us to turn left to a heading of 340. The first officer turned to that heading. Shortly thereafter; we were given an easterly heading; and the controller asked if we had programmed the departure correctly. I told him that we had plugged it in and hooked it up; but that we had experienced a wake turbulence upset that caused us to turn right; and that we were trying to level the aircraft and turn back to the left. He responded 'ok.' the first officer and I then had a discussion about what had happened and he told me that; at some point after the onset of the upset; he was leading the turn a nezug. He thought it was a flyby waypoint; like those that he had experienced at international airport departures in the past. I told him that nezug is not a flyby waypoint; and this fact is reemphasized in our company [briefing] page for seattle. I was unaware of his thought process; and because this started as a wake turbulence upset; I thought he was still having difficulty leveling the aircraft. In reality; somewhere in the process; he had decided to lead the turn; and he was doing that. I don't know if there was a loss of separation with another aircraft in this event; but the departure is noise sensitive; and the controller seemed to be watching us closely. This event would probably have prevented if we had held a more detailed discussion in the preflight briefing; so that I knew the first officer understood that nezug is not a flyby waypoint. The company [briefing] page for sea emphasizes this. When I fly these types of sids; I normally always engage the autopilot soon after takeoff; and a properly programmed departure is always precisely flown. I don't like to hand-fly these things; and I don't like watching first officers chase the flight director; sometimes imprecisely; on any of these departures. In the future; I will spend more time discussing these sids; so that we both understand what is expected; and I will be more forceful in my recommendation to always use the autopilot to fly the departure.

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Original NASA ASRS Text

Title: B757 Captain reported wake vortex encounter in trail of a B737-800 on departure from SEA that resulted in a course deviation.

Narrative: We departed SEA Runway 34C in clear weather. [A] 737-800 had preceded us on departure. First Officer; hand-flying; with LNAV and VNAV selected on the MCP; MOUNTAIN6 Departure. SID calls for over flying NEZUG and then a turn right to a heading of 070; about 2 miles prior to NEZUG; at 5;000 FT; we [experienced] a wake turbulence upset; which caused nearly 30 degrees of right bank. First Officer appeared to react properly; as the bank angle initially came back to about 20 degrees of right bank; but the turbulence continued. The bank angle then varied between 20 to 25 degrees of right bank. I was focused on the aircraft attitude; and was concerned that the First Officer was having trouble leveling the wings; so I asked him; 'Are you able to level the wings?' I was about to take control of the aircraft. I didn't hear him answer; as ATC directed us to turn left to a heading of 340. The First Officer turned to that heading. Shortly thereafter; we were given an easterly heading; and the Controller asked if we had programmed the departure correctly. I told him that we had plugged it in and hooked it up; but that we had experienced a wake turbulence upset that caused us to turn right; and that we were trying to level the aircraft and turn back to the left. He responded 'OK.' The First Officer and I then had a discussion about what had happened and he told me that; at some point after the onset of the upset; he was leading the turn a NEZUG. He thought it was a flyby waypoint; like those that he had experienced at international airport departures in the past. I told him that NEZUG is not a flyby waypoint; and this fact is reemphasized in our company [briefing] page for Seattle. I was unaware of his thought process; and because this started as a wake turbulence upset; I thought he was still having difficulty leveling the aircraft. In reality; somewhere in the process; he had decided to lead the turn; and he was doing that. I don't know if there was a loss of separation with another aircraft in this event; but the departure is noise sensitive; and the Controller seemed to be watching us closely. This event would probably have prevented if we had held a more detailed discussion in the preflight briefing; so that I knew the First Officer understood that NEZUG is not a flyby waypoint. The company [briefing] page for SEA emphasizes this. When I fly these types of SIDs; I normally always engage the autopilot soon after takeoff; and a properly programmed departure is always precisely flown. I don't like to hand-fly these things; and I don't like watching first officers chase the flight director; sometimes imprecisely; on any of these departures. In the future; I will spend more time discussing these SIDs; so that we both understand what is expected; and I will be more forceful in my recommendation to always use the autopilot to fly the departure.

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.