Narrative:

We were level at FL360 on track C; slop [(strategic lateral offset procedure )]1 [mile] right; I was the pilot flying. Flight was smooth; in clear skies; with upper winds blowing straight crosswind right to left. On the TCAS I noted traffic coming up on our right and slowly overtaking us. As he passed; I noted he was a B747; and he was sloped further right than we were. Having previously flown the 747; I knew he was going to outrun us; and with the wind; I elected to slop 2 [miles] right; which put us directly in line with him. Everything was smooth; no flight/wake turbulence present. His contrails were present and they were blowing to our left. We got an ECAM message; navigation TCAS fault. Performed the ECAM action; consulted the QRH; and checked the system reset tables in the fleet bulletins; for any reset help. We switched transponders; turned it offirst officern; no help. Contacted mx control for possible reset options; they said nothing could be done and indicated there was a history of problems and to write it up.subsequently; I noticed the B747s contrails were getting closer to us and noticed the upper winds on the nd had changed to a straight tailwind. We [then] ran into wake turbulence that rolled the aircraft 15 degrees left; then 20 degrees right with extensive turbulence. I immediately turned the aircraft to the right using the heading knob; while the first officer turned the seatbelt sign on. The turbulence/wake lasted about 40 to 50 seconds. We had moved about 6 NM right of track. I slowly started working the aircraft back towards the track; still at FL360. The purser checked in; everything was good in the back of the cabin; but I left the seat belt sign on as a precaution. I had worked the aircraft back to about 2.5 miles of the track when we started to get light bounces indicative of wake turbulence. Winds were still a straight tailwind. We sent a request for a climb to FL380; but were told unable due to traffic; in the meantime I had looked at the briefing card to see what deviation in altitude we could do to get out of this in case we ran into it again; and under WX deviations I read descend 300 feet; but I didn't want to descend due to vortices going downward. The contrails had subsequently moved away and dissipated from view.we [then] ran into wake turbulence again. This encounter was the same with a bit more roll excursion. I turned the aircraft to the right; but also climbed to FL363. We were able to get out of it a bit quicker; but it still lasted about 30 seconds. We were roughly 8 miles right of track at FL363; and I was working the aircraft back towards the track when we received a cpdlc message asking if we were at FL363. We acknowledged we were; and I directed the first officer to call gander radio and tell them due to second wake turbulence encounter if we could have higher or cruise at FL363. Both were denied; so I descended back to FL360. Subsequently; we got a reroute from gander oceanic. Because we had no TCAS; I called gander radio to find out if the B747 traffic which had caused the wake turbulence was given the same routing and was told he was on the exact routing we had been given. I called on 123.45 to confirm this with [the B747 flight crew] and they confirmed they were. After checking in with gander center later at the fir; they didn't say anything in relation to our excursions. Rest of flight routine.

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Original NASA ASRS Text

Title: A330 Captain reported encountering wake turbulence at FL360 from a preceding B747 on a North Atlantic oceanic track.

Narrative: We were level at FL360 on Track C; SLOP [(Strategic Lateral Offset Procedure )]1 [mile] right; I was the Pilot Flying. Flight was smooth; in clear skies; with upper winds blowing straight crosswind right to left. On the TCAS I noted traffic coming up on our right and slowly overtaking us. As he passed; I noted he was a B747; and he was SLOPed further right than we were. Having previously flown the 747; I knew he was going to outrun us; and with the wind; I elected to SLOP 2 [miles] right; which put us directly in line with him. Everything was smooth; no flight/wake turbulence present. His contrails were present and they were blowing to our left. We got an ECAM message; NAV TCAS FAULT. Performed the ECAM action; consulted the QRH; and checked the System Reset Tables in the Fleet Bulletins; for any reset help. We switched transponders; turned it OFF/ON; no help. Contacted MX Control for possible reset options; they said nothing could be done and indicated there was a history of problems and to write it up.Subsequently; I noticed the B747s contrails were getting closer to us and noticed the upper winds on the ND had changed to a straight tailwind. We [then] ran into wake turbulence that rolled the aircraft 15 degrees left; then 20 degrees right with extensive turbulence. I immediately turned the aircraft to the right using the Heading knob; while the First Officer turned the SEATBELT sign ON. The turbulence/wake lasted about 40 to 50 seconds. We had moved about 6 NM right of track. I slowly started working the aircraft back towards the track; still at FL360. The Purser checked in; everything was good in the back of the cabin; but I left the SEAT BELT sign ON as a precaution. I had worked the aircraft back to about 2.5 miles of the track when we started to get light bounces indicative of wake turbulence. Winds were still a straight tailwind. We sent a request for a climb to FL380; but were told unable due to traffic; In the meantime I had looked at the briefing card to see what deviation in altitude we could do to get out of this in case we ran into it again; and under WX deviations I read descend 300 feet; but I didn't want to descend due to vortices going downward. The contrails had subsequently moved away and dissipated from view.We [then] ran into wake turbulence again. This encounter was the same with a bit more roll excursion. I turned the aircraft to the right; but also climbed to FL363. We were able to get out of it a bit quicker; but it still lasted about 30 seconds. We were roughly 8 miles right of track at FL363; and I was working the aircraft back towards the track when we received a CPDLC message asking if we were at FL363. We acknowledged we were; and I directed the First Officer to call Gander Radio and tell them due to second wake turbulence encounter if we could have higher or cruise at FL363. Both were denied; so I descended back to FL360. Subsequently; we got a reroute from Gander Oceanic. Because we had no TCAS; I called Gander Radio to find out if the B747 traffic which had caused the wake turbulence was given the same routing and was told he was on the exact routing we had been given. I called on 123.45 to confirm this with [the B747 flight crew] and they confirmed they were. After checking in with Gander Center later at the FIR; they didn't say anything in relation to our excursions. Rest of flight routine.

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.