A BAE4101 ENCOUNTERS WAKE TURB FROM A B747-400 DURING APCH INTO JFK; NY. ENCOUNTER ROLLS THE BAE4101 INTO A 40 DEG BANK EVEN WITH A 6 MI SEPARATION.

Narrative

WHILE ON VOR RWY 13L APCH JFK OVER CRI VORTAC AND CLRED FOR VISUAL APCH TO RWY 13L IN SMOOTH AIR APPROX 5 MI IN- TRAIL OF ACR B747 WAS CAUGHT IN WAKE TURB AND ROLLED APPROX 45 DEGS R BANK. RECOVERED ACFT WITH FULL AILERON (L) AUTH RUDDER AND ELEVATOR TO CLB OUT OF ROLL EFFECT. AILERON WITH FULL L APPLICATION WAS NOT ENOUGH TO COUNTER ROLL EFFECT. LANDED WITHOUT FURTHER INCIDENT. SURE WISH THE BIG GUYS WOULD STAY ON GLIDE PATH OR CORRECT ALT ON NON PRECISION APCHS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR PARTICIPATED IN THE WAKE TURB STRUCTURED CALLBACK STUDY. RPTR ANTICIPATED THAT WAKE MIGHT BE ENCOUNTERED SO HE GOT CLRNC TO CROSS CRI AT HIS DISCRETION OF ALT. HE FLEW 400 FT HIGHER SO AS TO AVOID WAKE; HOWEVER; WHAT HE DIDN'T KNOW WAS THE PRECEDING ACFT CROSSED CRI HIGHER THAN NORMAL WHICH RESULTED IN FLYING INTO THE WAKE OF THE B747-400. THE BAE4101 ENCOUNTERED THE WAKE AND ROLLED 40 DEGS WITH HARDLY ANY OTHER FLT PATH DISPLACEMENT. THE EFFECT OF STRESS FROM THE EVENT DIDN'T HAPPEN UNTIL THE FLC WAS ON THE GND FOR 45 MINS. THEN THE FLC BEGAN TO BE VERY BOTHERED BY THE ENCOUNTER.