ACR X LOSS OF ACFT CTL DUE TO B757 WAKE TURB.

Narrative

ACR X ON APCH; FO FLYING; 5 MI IN TRAIL WITH A B757; OUR ACFT ROLLED L. FO RESPONDED WITH NEARLY FULL OPPOSITE AILERON AND RETURNED ACFT TO LEVEL FLT. APPROX 1 SECOND LATER; VORTEX WAS RE-ENCOUNTERED WITH ACFT AGAIN ROLLING L. I ASSISTED FO IN APPLYING FULL OPPOSITE AILERON; BUT WAS UNABLE TO STOP ROLL. FULL PWR WAS APPLIED AND A MISSED APCH WAS INITIATED. WE RETURNED FOR AN UNEVENTFUL LNDG. THERE WERE NO RPTED INJURIES THOUGH THE FLT ATTENDANT; WHO WAS SEATED IN THE FLT ATTENDANT'S AFT FACING JUMPSEAT WITH 4 POINT HARNESS ATTACHED; WAS THROWN AGAINST SIDE WALL OF CABIN BY THE ROLL. NO DAMAGE TO ACFT WAS DISCOVERED. AS A LCL SAFETY CHAIRMAN FOR OUR AIRLINE; I WAS RESPONSIBLE FOR DISTRIBUTING THE ADVISORY LETTER FROM THE FAA ADMINISTRATOR REGARDING WAKE TURB FROM B- 757'S AND WAS VERY AWARE OF THE HAZARD. ON THIS PARTICULAR APCH; WHEN I SAW THE 757 MAKE A VISUAL R BASE ENTRY AHEAD OF US; I DISCUSSED THE POSSIBILITY OF WAKE FROM THE ACFT. WE CONFIRMED TWR'S ADVISORY OF '5 IN TRAIL' WITH OUR TCASII DISPLAY. UNFORTUNATELY; SINCE WE WERE ON DISSIMILAR APCHS TO A COMMON RWY; IT WAS IMPOSSIBLE TO PLOT HIS FLT PATH AND ADJUST OURS ACCORDINGLY. IT SHOULD BE NOTED THAT ON ILS'S; WE'VE HAD LESS THAN 5 MI SEPARATION FOLLOWING 757'S WITH NO PROBS. I CAN ONLY ASSUME THAT OUR APCH ALT WAS LOWER THAN HIS. CONTRIBUTING TO THE PROB WAS THAT THE TWR WAS RPTING CALM WINDS.