Dash 8 Series Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Inflight Event / Encounter Wake Vortex Encounter
General None Reported / Taken
Environment - Non Weather Related; Procedure
The flight was on the downwind leg at approximately 6;000 feet for a planned landing on 34L in SEA. We were approximately 6 miles behind a 737 and given a descent to 4;000 feet when we were hit by wake turbulence. It was without any warning and was a couple of very hard vertical jolts. It only lasted 2-3 seconds. The ride up to that point and after the event was smooth. The winds at that altitude were very light.My intention with this [report] is bring to the attention of those who establish separation for wake turbulence my experiences. It is NOT to imply any loss of separation by the controllers but to hopefully have a renewed review of time and distance separation. It seems as though the frequency of wake turbulence has increased in the last couple of years. Once on final approach and the preceding traffic is in sight I can maintain a safe glide path to stay out of the wake. But when on a GPS STAR or vectors it is very difficult to avoid. Not only is an unexpected encounter somewhat unsettling to the crew; it is much more frightening to passengers.I also have a concern that new pilots have had limited exposure to wake turbulence and how to avoid it when able. During operating experience I have been with new pilots on final behind airline aircraft. When I suggest staying slightly high on the glideslope they seem somewhat confused as to why. This offers a teachable moment when we start getting the wake of the preceding aircraft.My ultimate recommendation would be for increased separation by adding increased in trail spacing or allowing us to offset laterally to avoid an encounter. Also; incorporating [additional] emphasis for new hires on avoiding wake turbulence when operating in high density traffic areas.
Dash 8 Captain reported encountering wake turbulence on approach to SEA in trail of a B737. Reporter suggested a review of in-trail guidelines.