SMA ENCOUNTERS WAKE TURB FROM B-747.

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THIS WAS PROMPTED BY THE RECENT REQUEST IN CALLBACK FOR WAKE TURB INFO. IT OCCURRED IN 1988 AND MADE A SUFFICIENTLY SIGNIFICANT IMPRESSION THAT I NOTED IT IN MY LOGBOOK. IF IT DOESN'T MEET YOUR RECENCY REQUIREMENTS; PLEASE DISCARD. 2 OF MY CHILDREN AND I WERE ON RTE FROM BED TO ORF. VISIBILITY WAS UNLIMITED. THERE WAS A STRONG FLOW OF AIR FROM THE SW. 1 DAUGHTER WAS IN THE R REAR SEAT AND THE OTHER WAS IN THE R FRONT SEAT. ABOUT 10 MI SW OF JFK ON V-1 AT 8000 FT; THE CTLR INFORMED ME OF 747 TFC THAT WOULD BE CLBING THROUGH MY ALT; S OF MY POS; AND WARNED 'CAUTION; WAKE TURB.' I KNEW I WOULD BE BELOW THE PATH OF THE 747; WAS CONCERNED WITH THE FLOW OF AIR FROM THE SW; BUT ASSUMED ANY TURB WOULD BE BELOW MY ALT WHEN I CROSSED THE AREA. NONETHELESS; I TIGHTENED MY SEAT BELT AND ASKED MY DAUGHTERS TO DO THE SAME. UNBEKNOWNST TO ME; MY DAUGHTER IN THE REAR WAS NOT WEARING HER HEADSET AND DID NOT HEAR MY REQUEST. THE FLT HAD BEEN QUITE SMOOTH. WHEN WE HIT THE WAKE TURB; THE PLANE EXPERIENCED A DRAMATIC DOWNWARD MOTION -- THE IMPACT BEING A SUDDEN; FIERCE JOLT. NO ROLLING TENDENCY WAS EXPERIENCED. MY DAUGHTER IN THE REAR SEAT HIT THE CEILING OF THE ACFT WITH SUFFICIENT FORCE TO CAUSE A LARGE SCALP BRUISE. BOTH MY FRONT SEAT DAUGHTER AND I WERE RESTRAINED BY OUR SEAT BELTS. THERE IS NO DOUBT IN MY MIND THAT THE CAUSE OF THIS INCIDENT WAS WAKE TURB. MY HDG AT THE TIME WAS ABOUT 220 DEGS AND I ESTIMATE THE COURSE OF THE 747 TO HAVE BEEN ABOUT 280 DEGS. IN RETROSPECT; IT SEEMS TO ME I WAS IN A PRECARIOUS POS NO MATTER WHAT I DID (EXCEPT FOR A 180 DEG TURN). BETTER SENSITIVITY TO THIS SIT BY THE CTLR MIGHT HAVE RESULTED IN CLB INSTRUCTIONS TO THE 747 WHICH WOULD HAVE CROSSED MY COURSE BELOW MY ALT OR BEHIND ME -- WHICH WOULD HAVE AVOIDED THIS INCIDENT.