B767 flight crew reported encountering wake turbulence on descent into EHAM/AMS in trail of a B777 that resulted in rolls to the left and right; and momentary stick shakers.
Synopsis
B767 flight crew reported encountering wake turbulence on descent into EHAM/AMS in trail of a B777 that resulted in rolls to the left and right; and momentary stick shakers.
Narrative
Descending through FL070 for FL045 at 250 KIAS with Schiphol approach. We began to get uncommanded left and right rolling that was associated with a preceeding B-777-200 in the Radar pattern for AMS that we were following. After 2 or 3 good left and right rolls; rolling approx 10 degrees in each direction; I disengaged the autopilot to dampen out the rolling moment. As I began hand flying the aircraft we were at 1 degree of pitch attitude 250 KIAS descending to FL045; as the wing rock continued we began to encounter some turbulence associated with wake turbulence. Almost immediately after the turbulence was encountered I received 2 very brief stick shaker activations and the amber low speed awareness band shot up almost instantly. Each activation was less than a second and I would say both activations of the stick shaker occurred within 2 seconds. I continued to hand flying the aircraft and recovered from the wake turbulence encounter. The airplane was still clean and approximately 290;000 LBS in a descent with wings level and in a 1000-1500 FPM rate of descent with autopilot and auto throttles in LNAV/VNAV at the time we encountered the wake. We were in 1G flight in the descent. I then inquired with Approach as to the type of airplane we were following and reported the event.
Second reporter narrative
While on descent on the LAMSO2A; we were cleared to descend to FL045 at an assigned speed of 250 knots. As we passed through FL070 the plane banked approximately 5-10 degrees to the right; and then began to do the same thing to the left. It started to become clear that we might be encountering wake turbulence. I raised my hands up to be ready at the flight controls to back up the Pilot Flying. The Captain who was Pilot Flying; was already grabbing the controls and announced that he was turning off the autopilot. Around the time he was taking manual control of the aircraft; the plane banked back to the right about 10-15 degrees; but at a much faster rate which was caused by the proceeding aircraft's wake. The PF immediately corrected; but due to the speed of the rate of bank caused by the wake; it caused two momentary stick shaker activation. We then assessed our current speed at this time; which was 250 knots with a descent rate of 1000-1500 fpm. The amber band on the airspeed indicator moved up to approximately 240 knots when I glanced at it and then moved back down once the aircraft was stabilized from the oscillations. We believe the aircraft stayed around 1G the entire encounter. The whole occurrence lasted around 10 seconds. ATC coincidentally then gave a us a descent to 3000 feet and a heading to the right of our current course. I read back the clearance and queried what kind of aircraft we were following. ATC replied that we were following a B777; and that our new heading would take our aircraft out of the B777 path. After the we felt confident we were clear of the wake turbulence. The autopilot was reengaged and we completed an uneventful arrival and approach.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.