SMT ACFT FOLLOWING B757 WAKE TURB INCIDENT.

Narrative

I WAS PF; FO; ON BE58 RETURNING TO BASE IN DCA AT NIGHT WITH CLR SKIES AND UNRESTRICTED VISIBILITY. WE WERE VECTORED DOWNWIND AND CLRED VISUAL APCH TO FOLLOW B757 ON 5 MI FINAL. ATC PROVIDED ALL THE PROPER CAUTIONS -- 'CAUTION WAKE TURB; B757' 'ALT 1500 FT OVER THE WILSON BRIDGE.' I WAS VERY FAMILIAR WITH WAKE TURB AVOIDANCE PROCS AND CROSSED THE WILSON BRIDGE AT 1700 FT TO STAY ABOVE THE B757 FLT PATH. WE OBSERVED B757 TOUCHDOWN POINT AND PLANNED TO LAND BEYOND IT. I ALSO FELT THAT THE 757'S FASTER APCH SPD WOULD PUT US ALMOST 1 MIN OR SO IN TRAIL; SO THE WAKE WOULD HAVE DISSIPATED AS WELL AS BE BELOW OUR GLIDEPATH. UPON OUR LNDG FLARE; WE ENCOUNTERED GENTLE ROCKING MOTION FROM THE WAKE. I ELECTED TO GAR AS I WAS CONCERNED THAT WE WOULD HIT THE WAKE CORE. A NORMAL APCH AND LNDG WERE SUBSEQUENTLY MADE. THE WAKE PERSISTED BECAUSE I HAD FORGOTTEN THAT THE ATIS HAD WINDS AT 130 DEGS AT 3 KTS (A SLIGHT TAILWIND FOR LNDG ON RWY 36). I WAS AMAZED AT THE LONGEVITY OF THE WAKE UNDER THESE QUARTERING TAILWIND CONDITIONS. IRONICALLY; I HAD ATTENDED A MEETING ON B757 WAKE THE AFTERNOON OF THE INCIDENT. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: RPTR STATED THAT; ALTHOUGH HE WAS KNOWLEDGEABLE ABOUT WAKE TURB; HE WOULD REMAIN HIGHER ON GLIDEPATH AND LAND LONGER WHEN IN THE SAME SIT. HE BELIEVES ATC SHOULD GIVE SURFACE WIND CONDITIONS MORE OFTEN WHEN WAKE TURB COULD BE A FACTOR. RPTR WAS A STRUCTURED CALLBACK PARTICIPANT.