Flight Crew Air Transport Pilot (ATP)
Distraction; Communication Breakdown
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 Returned To Clearance
Environment - Non Weather Related; Human Factors
On A590; after crossing PASRO; we noticed an airliner directly above us and started encountering turbulence; which we believed was wake turbulence. In order to avoid the turbulence; we deviated left upwind one mile left of course. In the distraction of discussing where to avoid the turbulence; we failed to ask for clearance to deviate left of course. Control asked us about the deviation via CPDLC; and informed us we needed to ask to deviate left. We took out the offset; and returned to the track (the overtaking airplane was far enough ahead at this point). There were no other airplanes either visually or on TCAS that we were aware of; and we believe no separation issues were caused as a result of our deviation.Channelized attention to our position relative to the overtaking aircraft led to a breakdown in contacting ATC.
B777 First Officer reported deviating left off track on their trans-Pacific route to avoid wake turbulence; but failed to ask ATC for approval.