Narrative:

We were on the VOR runway 13L approach to jfk at 1500 ft MSL crossing the cri VOR when we encountered wake turbulence created by a B757 6 mi ahead conducting the same approach to the same runway. This traffic had been pointed out to us by ATC as being 6 mi ahead and we had this aircraft in sight. As a rule, I usually try to maintain slightly higher than heavy jet traffic I am following, but this particular approach calls for a mandatory 1500 ft for the segment leading up to the cri VOR unless otherwise authority/authorized by ATC. The turbulence began as a moderate chop but quickly developed into a hard roll to the right of about 40 degrees of bank. I corrected back to wings level, but encountered a second hard roll to the right -- also about 40 degrees of bank. By this time, I had throttled up to climb thrust and was attempting to climb out of it. I found smooth air at 1900 ft MSL. I informed ATC we were climbing out of wake turbulence and that our approach to the airport would be higher than normal. The remainder of the approach and landing was turbulence free. Conditions were good for preserving a wake at the time of our encounter. Light winds aloft and very stable air. I don't think 6 mi is enough spacing behind a B757 for a mid size cpr jet. Next time I do this approach behind a heavy aircraft I will request a higher altitude to the FAF and/or more spacing. Although we rolled only about 40 degrees of bank, the roll rate was very impressive. I wouldn't like to sample it again.

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Original NASA ASRS Text

Title: WAKE TURB ENCOUNTER WHEN FOLLOWING A B757 ON THE CRI VOR APCH TO JFK, NY.

Narrative: WE WERE ON THE VOR RWY 13L APCH TO JFK AT 1500 FT MSL XING THE CRI VOR WHEN WE ENCOUNTERED WAKE TURB CREATED BY A B757 6 MI AHEAD CONDUCTING THE SAME APCH TO THE SAME RWY. THIS TFC HAD BEEN POINTED OUT TO US BY ATC AS BEING 6 MI AHEAD AND WE HAD THIS ACFT IN SIGHT. AS A RULE, I USUALLY TRY TO MAINTAIN SLIGHTLY HIGHER THAN HVY JET TFC I AM FOLLOWING, BUT THIS PARTICULAR APCH CALLS FOR A MANDATORY 1500 FT FOR THE SEGMENT LEADING UP TO THE CRI VOR UNLESS OTHERWISE AUTH BY ATC. THE TURB BEGAN AS A MODERATE CHOP BUT QUICKLY DEVELOPED INTO A HARD ROLL TO THE R OF ABOUT 40 DEGS OF BANK. I CORRECTED BACK TO WINGS LEVEL, BUT ENCOUNTERED A SECOND HARD ROLL TO THE R -- ALSO ABOUT 40 DEGS OF BANK. BY THIS TIME, I HAD THROTTLED UP TO CLB THRUST AND WAS ATTEMPTING TO CLB OUT OF IT. I FOUND SMOOTH AIR AT 1900 FT MSL. I INFORMED ATC WE WERE CLBING OUT OF WAKE TURB AND THAT OUR APCH TO THE ARPT WOULD BE HIGHER THAN NORMAL. THE REMAINDER OF THE APCH AND LNDG WAS TURB FREE. CONDITIONS WERE GOOD FOR PRESERVING A WAKE AT THE TIME OF OUR ENCOUNTER. LIGHT WINDS ALOFT AND VERY STABLE AIR. I DON'T THINK 6 MI IS ENOUGH SPACING BEHIND A B757 FOR A MID SIZE CPR JET. NEXT TIME I DO THIS APCH BEHIND A HVY ACFT I WILL REQUEST A HIGHER ALT TO THE FAF AND/OR MORE SPACING. ALTHOUGH WE ROLLED ONLY ABOUT 40 DEGS OF BANK, THE ROLL RATE WAS VERY IMPRESSIVE. I WOULDN'T LIKE TO SAMPLE IT AGAIN.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.