Narrative:

I have been flying these rtes from south florida to and from the bahama islands for approximately 7 yrs in C402's. In this time, I have had 3 definite wake turbulence encounters and numerous suspicious 'bumps' on this arrival into the fll/mia area. The center clears all light twin and slow traffic to 6000 ft and all jet/fast aircraft to 7000 ft in the vicinity of mrlin intersection. We often cross paths at mrlin, the slower aircraft then following the large transports down 68V (southwest) into the fll traffic pattern. Naturally the large aircraft pulls ahead, when enough separation obtained, (usually about 5- 10 mi northeast of fll) the large aircraft is descended to 6000 ft, turned right (wbound), then descended to 4000 ft and on into the approach for runway 09L fll. The light slow traffic follows, often getting descent clearance after the large aircraft at flight paths often cross, intersecting altitudes. In other words, the light aircraft flies through the same place as a large aircraft, through its 'wake path,' usually within 10 mi. Approach will advise of traffic, however, especially in IMC conditions, the light aircraft is still restr to fly the same arrival. (Due to geographics, there is not a lot of room to work with here). For example, one memorable encounter. At about 30 DME from fll, approach advised of heavy L1011 traffic passing 1000 ft overhead, same direction. I visually called traffic and watch him out of sight. With approach duties, I forgot about him. At about 10 DME from fll, I encountered the wake. It was a hard roll, left, about 60 degrees before I could stop it. (It woke the passenger). I queried the approach controller. She tersely reminded me she had informed me and I had called the traffic in sight. On informing her I had unexpectedly hit the wake, she confirmed the traffic was 10 mi ahead. I estimate our speed difference at 90 KTS. This would mean approximately 9 mins elapsed, with 1000 ft vertical separation, before my flight path intersected the L1011's 'wake path.' I feel the potential for more encounters is threatening. If I have had numerous encounters, and I am only one of many inbound (even one of many commuter flts), there must be more encounters occurring. I feel the light/slow traffic should have a different arrival, if only by a few degrees, and perhaps a lower arrival altitude to separate and lessen the number of times we intersect flight path courses with large aircraft. Callback conversation with reporter revealed the following: reporter participated in wake turbulence callback questionnaire. She had been flying this route for 7 yrs and was well aware of the wake problems at fll. She recommends a second arrival route for small aircraft.

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Original NASA ASRS Text

Title: WAKE TURB ENCOUNTER DUE TO XING ARR RTES.

Narrative: I HAVE BEEN FLYING THESE RTES FROM S FLORIDA TO AND FROM THE BAHAMA ISLANDS FOR APPROX 7 YRS IN C402'S. IN THIS TIME, I HAVE HAD 3 DEFINITE WAKE TURB ENCOUNTERS AND NUMEROUS SUSPICIOUS 'BUMPS' ON THIS ARR INTO THE FLL/MIA AREA. THE CTR CLRS ALL LIGHT TWIN AND SLOW TFC TO 6000 FT AND ALL JET/FAST ACFT TO 7000 FT IN THE VICINITY OF MRLIN INTXN. WE OFTEN CROSS PATHS AT MRLIN, THE SLOWER ACFT THEN FOLLOWING THE LARGE TRANSPORTS DOWN 68V (SW) INTO THE FLL TFC PATTERN. NATURALLY THE LARGE ACFT PULLS AHEAD, WHEN ENOUGH SEPARATION OBTAINED, (USUALLY ABOUT 5- 10 MI NE OF FLL) THE LARGE ACFT IS DSNDED TO 6000 FT, TURNED R (WBOUND), THEN DSNDED TO 4000 FT AND ON INTO THE APCH FOR RWY 09L FLL. THE LIGHT SLOW TFC FOLLOWS, OFTEN GETTING DSCNT CLRNC AFTER THE LARGE ACFT AT FLT PATHS OFTEN CROSS, INTERSECTING ALTS. IN OTHER WORDS, THE LIGHT ACFT FLIES THROUGH THE SAME PLACE AS A LARGE ACFT, THROUGH ITS 'WAKE PATH,' USUALLY WITHIN 10 MI. APCH WILL ADVISE OF TFC, HOWEVER, ESPECIALLY IN IMC CONDITIONS, THE LIGHT ACFT IS STILL RESTR TO FLY THE SAME ARR. (DUE TO GEOGRAPHICS, THERE IS NOT A LOT OF ROOM TO WORK WITH HERE). FOR EXAMPLE, ONE MEMORABLE ENCOUNTER. AT ABOUT 30 DME FROM FLL, APCH ADVISED OF HVY L1011 TFC PASSING 1000 FT OVERHEAD, SAME DIRECTION. I VISUALLY CALLED TFC AND WATCH HIM OUT OF SIGHT. WITH APCH DUTIES, I FORGOT ABOUT HIM. AT ABOUT 10 DME FROM FLL, I ENCOUNTERED THE WAKE. IT WAS A HARD ROLL, L, ABOUT 60 DEGS BEFORE I COULD STOP IT. (IT WOKE THE PAX). I QUERIED THE APCH CTLR. SHE TERSELY REMINDED ME SHE HAD INFORMED ME AND I HAD CALLED THE TFC IN SIGHT. ON INFORMING HER I HAD UNEXPECTEDLY HIT THE WAKE, SHE CONFIRMED THE TFC WAS 10 MI AHEAD. I ESTIMATE OUR SPD DIFFERENCE AT 90 KTS. THIS WOULD MEAN APPROX 9 MINS ELAPSED, WITH 1000 FT VERT SEPARATION, BEFORE MY FLT PATH INTERSECTED THE L1011'S 'WAKE PATH.' I FEEL THE POTENTIAL FOR MORE ENCOUNTERS IS THREATENING. IF I HAVE HAD NUMEROUS ENCOUNTERS, AND I AM ONLY ONE OF MANY INBOUND (EVEN ONE OF MANY COMMUTER FLTS), THERE MUST BE MORE ENCOUNTERS OCCURRING. I FEEL THE LIGHT/SLOW TFC SHOULD HAVE A DIFFERENT ARR, IF ONLY BY A FEW DEGS, AND PERHAPS A LOWER ARR ALT TO SEPARATE AND LESSEN THE NUMBER OF TIMES WE INTERSECT FLT PATH COURSES WITH LARGE ACFT. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: RPTR PARTICIPATED IN WAKE TURB CALLBACK QUESTIONNAIRE. SHE HAD BEEN FLYING THIS RTE FOR 7 YRS AND WAS WELL AWARE OF THE WAKE PROBS AT FLL. SHE RECOMMENDS A SECOND ARR RTE FOR SMALL ACFT.

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.