EMB ERJ 170/175 ER/LR
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown
ATC Issue All Types; Inflight Event / Encounter Wake Vortex Encounter
Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action; Flight Crew Requested ATC Assistance / Clarification
Environment - Non Weather Related; Procedure
Encountered moderate wake turbulence (10-12 degrees roll) descending on the HAWKS Arrival into Seattle. The traffic we were following was well beyond 5 miles ahead of us; we estimate about 9 miles. We encountered wake approaching BREVE and had to slow down below the 250kts published speed to exit the wake and maintain control of the aircraft.  Slowing down was effective in decreasing and exiting the wake.  We had briefed wake turbulence avoidance earlier in the day. So we were already being cognizant of creating spacing and yet we still encountered wake at a conservative distance. Low visibility approaches were in effect so there was aircraft congestion and the controller was busy on the radio. Initially when we encountered wake we tried to notify the controller we needed to slow below published speed to exit it. However she was occupied by radio congestion to get the message across and didn't get our request to slow for wake; until after we already passed the restriction. When we finally connected with the controller she wanted us to speed back up to the published speeds to maintain her spacing into Seattle. I assessed as PIC that we had created enough separation by slowing so we resumed published speeds per her request. We only hit minimal wake turbulence thereafter.  I saw the controller's preoccupation with spacing and radio congestion a threat. Although the autopilot did not disconnect; I disconnected it when I saw the airplane to through 10 degree rolling motions.I would like to see more aircraft spacing more than 5 miles behind a heavy. I learned that controllers sometimes do not create separation for wake. It is up to the pilots to be proactive. Controller preoccupation when weather is a consideration is a threat. Controllers will unfortunately try to give clearances that may be unsafe and it is up to the crew decide and deviate if safety is compromised.
EMB-175 Captain reported encountering wake turbulence 9 miles in trail of a heavy jet on arrival into SEA.