B777 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 129; Flight Crew Total 10531; Flight Crew Type 129
Training / Qualification
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Human Factors
I had just returned to the cockpit from my break/rest period. I was given a quick brief of our flights progress. We had been cleared as filed on a random route at FL370. The flight log was in order and filled out properly; HF frequencies were tuned; and a SELCAL check with Shanwick Oceanic had already been performed. Ten minutes later we received a SELCAL from Shanwick. Upon contacting them via HF; we were asked why our last position report showed us on a 3 mile right offset. I quickly checked the route to confirm our position/Strategic Lateral Offset Procedure (SLOP). It did indeed show R3. I asked the other First Officer the reason for the 3 mile offset. He said it was entered because of unusually strong wake turbulence from the aircraft 20 miles ahead and 1;000 feet above. He relayed that to Shanwick and stated that we would return to an offset of 0 or 1R. We returned to a SLOP of R1. I asked the First Officer if they sent a request for a right deviation via CPDLC. He said no. The rest of the crossing and flight were uneventful.
B777 First Officer reported returning from break and being questioned by Shanwick as to why they were offset 3 NM to the right of track. The IRO stated that the offset was initiated to avoid wake turbulence from the preceding aircraft without requesting a clearance to do so.