B767 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 126; Flight Crew Total 7521; Flight Crew Type 1679
Situational Awareness
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Wake Vortex Encounter
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Human Factors; Environment - Non Weather Related
Due to wake turbulence from a preceding aircraft and prevailing winds we elected to offset two miles to the left of track to keep us clear of the moderate turbulence. I had forgotten that SLOPing left of course is not authorized per the FOM. Sometime later; while I was on break; Gander Oceanic queried us as to why we were showing left of course and the Relief Pilot and First Officer corrected the error and returned to the center of the track. (SLOPing right of course would've put us back into the wake turbulence.)
During cruise we entered the wake of a proceeding aircraft causing 5 to 6 sec of moderate turbulence. I decided due to wind direction to SLOP left of course to get out of wake. Once clear though I maintained the 2L SLOP for what I would guess 20 minutes until queried by ATC to verify course. The Relief Pilot pointed out that a left SLOP was not authorized and I immediately corrected my course by deleting the left SLOP. The preceding aircraft was well clear.
B767 flight crew reported they improperly deviated left of course in oceanic airspace to avoid wake turbulence.