Narrative:

Wake turbulence encounter (minor, 20 degree roll maximum). We turned 14 mi final on the ILS localizer for runway 27L atl at 3500 ft MSL. ATC pointed out a B737 turning base to final 4 mi ahead of us, descending out of 6000 ft and cleared us for the visual approach. I expected, and we did encounter some wake when we reached the point where the other aircraft had descended through our altitude. I have seen this before, and will often ask for a slight heading change to offset my flight path. I feel that the issue of aircraft altitude, particularly when a larger aircraft descends through the altitude of the following aircraft's altitude, needs to be addressed. In atl, for instance, turboprop arrs are turned on the downwind leg 1000 ft below the jets, so at some point in time as the jet descends ahead, the flight paths must cross and the possibility for a wake encounter exists. Callback conversation with reporter revealed the following information: pilot participated in the structured callback wake turbulence program. Pilot wanted to fly into the wake of the preceding B737 to see just how much its wake affected his aircraft. Because of the distance and the type of aircraft he was following, the upset was not great. He rolled about 20 degrees and lost 50 ft. To him it was comforting that the B737 was minor in intensity. It did prove to him that his concern regarding the descent of bigger aircraft down through his altitude will always produce a wake to be encountered. He feels some procedure should be developed to move the following aircraft away from the wake by distance or heading change.

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Original NASA ASRS Text

Title: WAKE TURB ENCOUNTER ON FINAL APCH AT ATL.

Narrative: WAKE TURB ENCOUNTER (MINOR, 20 DEG ROLL MAX). WE TURNED 14 MI FINAL ON THE ILS LOC FOR RWY 27L ATL AT 3500 FT MSL. ATC POINTED OUT A B737 TURNING BASE TO FINAL 4 MI AHEAD OF US, DSNDING OUT OF 6000 FT AND CLRED US FOR THE VISUAL APCH. I EXPECTED, AND WE DID ENCOUNTER SOME WAKE WHEN WE REACHED THE POINT WHERE THE OTHER ACFT HAD DSNDED THROUGH OUR ALT. I HAVE SEEN THIS BEFORE, AND WILL OFTEN ASK FOR A SLIGHT HDG CHANGE TO OFFSET MY FLT PATH. I FEEL THAT THE ISSUE OF ACFT ALT, PARTICULARLY WHEN A LARGER ACFT DSNDS THROUGH THE ALT OF THE FOLLOWING ACFT'S ALT, NEEDS TO BE ADDRESSED. IN ATL, FOR INSTANCE, TURBOPROP ARRS ARE TURNED ON THE DOWNWIND LEG 1000 FT BELOW THE JETS, SO AT SOME POINT IN TIME AS THE JET DSNDS AHEAD, THE FLT PATHS MUST CROSS AND THE POSSIBILITY FOR A WAKE ENCOUNTER EXISTS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: PLT PARTICIPATED IN THE STRUCTURED CALLBACK WAKE TURB PROGRAM. PLT WANTED TO FLY INTO THE WAKE OF THE PRECEDING B737 TO SEE JUST HOW MUCH ITS WAKE AFFECTED HIS ACFT. BECAUSE OF THE DISTANCE AND THE TYPE OF ACFT HE WAS FOLLOWING, THE UPSET WAS NOT GREAT. HE ROLLED ABOUT 20 DEGS AND LOST 50 FT. TO HIM IT WAS COMFORTING THAT THE B737 WAS MINOR IN INTENSITY. IT DID PROVE TO HIM THAT HIS CONCERN REGARDING THE DSCNT OF BIGGER ACFT DOWN THROUGH HIS ALT WILL ALWAYS PRODUCE A WAKE TO BE ENCOUNTERED. HE FEELS SOME PROC SHOULD BE DEVELOPED TO MOVE THE FOLLOWING ACFT AWAY FROM THE WAKE BY DISTANCE OR HEADING CHANGE.

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.