Narrative:

Prior to entering track D east of entry point pikil. Level FL340. Heavy aircraft about 20 miles ahead of us on track D. Heavy aircraft was one mile left of track; in relation to our position. Wind from the north. Our position was one mile right of track. Heavy aircraft moves to centerline of track. A few minutes later wind shifted to the south to the southwest. We encountered the wake turbulence from the heavy 747 aircraft. Flight attendants were told to immediately take their seats over the PA system and the seat belt sign was turn on. I disconnected autopilot and aircraft was banked to left heading towards a 3L offset. The wake turbulence lasted about 25 seconds. ATC was notified about our 3L offset for wake turbulence. We called the flight attendants to make sure everybody was ok. Flight attendant a told us that all flight attendants were ok and that there were no injuries to passengers or flight attendants.two hours before landing s flight attendant told me that she might [have] pulled her right calf muscle while trying to get to her jumpseat. At that time she told me that she was ok and she had no pain. She said that she was ok and continue to work the flight. After arrival at the gate I asked her again if she was ok; and she said yes; but told me she was going to file a report with the company to be on the safe side. No assistance was requested from any crew member or passenger.

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Original NASA ASRS Text

Title: B777 Captain reported wake turbulence encounter 20 miles in trail of a B747 at FL340; which resulted in a minor injury to a flight attendant.

Narrative: Prior to entering track D east of entry point PIKIL. Level FL340. Heavy aircraft about 20 miles ahead of us on track D. Heavy aircraft was one mile left of track; in relation to our position. Wind from the north. Our position was one mile right of track. Heavy aircraft moves to centerline of track. A few minutes later wind shifted to the south to the southwest. We encountered the wake turbulence from the heavy 747 aircraft. Flight attendants were told to immediately take their seats over the PA system and the seat belt sign was turn on. I disconnected autopilot and aircraft was banked to left heading towards a 3L offset. The wake turbulence lasted about 25 seconds. ATC was notified about our 3L offset for wake turbulence. We called the flight attendants to make sure everybody was ok. Flight Attendant A told us that all flight attendants were ok and that there were no injuries to passengers or flight attendants.Two hours before landing s flight attendant told me that she might [have] pulled her right calf muscle while trying to get to her jumpseat. At that time she told me that she was ok and she had no pain. She said that she was ok and continue to work the flight. After arrival at the gate I asked her again if she was ok; and she said yes; but told me she was going to file a report with the company to be on the safe side. No assistance was requested from any crew member or passenger.

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.