Narrative:

CCC flight X scheduled ATR-42 service from orf to jfk. Jfk arrival ATIS was: information tango at KK50Z 1400 ft broken 3500 ft overcast visibility 7 mi light rain wind 110 degrees at 12 KTS, altimeter 29.90, landing ILS runway 04R and ILS runway 04L. New york approach initially assigned us the ILS runway 04R and then changed it to ILS runway 04L when we were about 10 mi out. Established on the runway 04L ILS at approximately 1000 ft we encountered wake turbulence which rolled the aircraft 45 degree right. I took control of the aircraft and exited the vortex. We landed without further incident. A question to the tower confirmed what we already knew -- our preceding traffic to runway 04L was a shorts commuter. Neither approach nor tower mentioned a preceding heavy 747 until I specifically asked what type was preceding us on the runway 04R ILS. It was then revealed that an air carrier B747 (flight Y) had preceded us by 4-5 mi on the ILS runway 04R. The east wind had drifted his left wing vortice directly into our flight path. To make matters worse, runways 04L and 04R are staggered with the touchdown zone on runway 04R approximately 3200 ft further down field than that of runway 04L. This places the runway 04R glidepath above the runway 04L glidepath and with an easterly wind heavy aircraft wake vortices descend into the runway 04L approach zone and as demonstrated are a distinct threat to aircraft on ILS runway 04L. Additionally, the pilots of CCC flight Z, also an ATR, told me they encountered wake turbulence during their arrival on the runway 04L ILS about 15 mins earlier. Upon hearing this I called kennedy tower and advised them of the encounters and our assessment of the wind/runway situation. They said they would 'look into it.' callback conversation with reporter revealed the following: reporter stated the magnitude of the wake turbulence at 1000 ft, but added that the turbulence was being felt all the way down final descent. It was the sudden change of turbulence at 1000 ft that bothered their flight path. As the aircraft rolled to the right in a 45 degree bank, the captain took over as PF. Captain stated that he would not let the same situation occur again. He would avoid the situation by refusing an ILS to runway 04L when a heavy aircraft is flying ILS to runway 04R with an east wind. Turbulence caused 45 degree bank, partial control loss for a period of 5 seconds, causing temporary emotional stress. Reporter's aircraft was an ATR 42 while the wake generating aircraft was a B-747.

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Original NASA ASRS Text

Title: WAKE TURB ENCOUNTER.

Narrative: CCC FLT X SCHEDULED ATR-42 SVC FROM ORF TO JFK. JFK ARR ATIS WAS: INFO TANGO AT KK50Z 1400 FT BROKEN 3500 FT OVCST VISIBILITY 7 MI LIGHT RAIN WIND 110 DEGS AT 12 KTS, ALTIMETER 29.90, LNDG ILS RWY 04R AND ILS RWY 04L. NEW YORK APCH INITIALLY ASSIGNED US THE ILS RWY 04R AND THEN CHANGED IT TO ILS RWY 04L WHEN WE WERE ABOUT 10 MI OUT. ESTABLISHED ON THE RWY 04L ILS AT APPROX 1000 FT WE ENCOUNTERED WAKE TURB WHICH ROLLED THE ACFT 45 DEG R. I TOOK CTL OF THE ACFT AND EXITED THE VORTEX. WE LANDED WITHOUT FURTHER INCIDENT. A QUESTION TO THE TWR CONFIRMED WHAT WE ALREADY KNEW -- OUR PRECEDING TFC TO RWY 04L WAS A SHORTS COMMUTER. NEITHER APCH NOR TWR MENTIONED A PRECEDING HVY 747 UNTIL I SPECIFICALLY ASKED WHAT TYPE WAS PRECEDING US ON THE RWY 04R ILS. IT WAS THEN REVEALED THAT AN ACR B747 (FLT Y) HAD PRECEDED US BY 4-5 MI ON THE ILS RWY 04R. THE E WIND HAD DRIFTED HIS L WING VORTICE DIRECTLY INTO OUR FLT PATH. TO MAKE MATTERS WORSE, RWYS 04L AND 04R ARE STAGGERED WITH THE TOUCHDOWN ZONE ON RWY 04R APPROX 3200 FT FURTHER DOWN FIELD THAN THAT OF RWY 04L. THIS PLACES THE RWY 04R GLIDEPATH ABOVE THE RWY 04L GLIDEPATH AND WITH AN EASTERLY WIND HVY ACFT WAKE VORTICES DSND INTO THE RWY 04L APCH ZONE AND AS DEMONSTRATED ARE A DISTINCT THREAT TO ACFT ON ILS RWY 04L. ADDITIONALLY, THE PLTS OF CCC FLT Z, ALSO AN ATR, TOLD ME THEY ENCOUNTERED WAKE TURB DURING THEIR ARR ON THE RWY 04L ILS ABOUT 15 MINS EARLIER. UPON HEARING THIS I CALLED KENNEDY TWR AND ADVISED THEM OF THE ENCOUNTERS AND OUR ASSESSMENT OF THE WIND/RWY SIT. THEY SAID THEY WOULD 'LOOK INTO IT.' CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: RPTR STATED THE MAGNITUDE OF THE WAKE TURB AT 1000 FT, BUT ADDED THAT THE TURB WAS BEING FELT ALL THE WAY DOWN FINAL DSCNT. IT WAS THE SUDDEN CHANGE OF TURB AT 1000 FT THAT BOTHERED THEIR FLT PATH. AS THE ACFT ROLLED TO THE R IN A 45 DEG BANK, THE CAPT TOOK OVER AS PF. CAPT STATED THAT HE WOULD NOT LET THE SAME SIT OCCUR AGAIN. HE WOULD AVOID THE SIT BY REFUSING AN ILS TO RWY 04L WHEN A HVY ACFT IS FLYING ILS TO RWY 04R WITH AN E WIND. TURB CAUSED 45 DEG BANK, PARTIAL CTL LOSS FOR A PERIOD OF 5 SECONDS, CAUSING TEMPORARY EMOTIONAL STRESS. RPTR'S ACFT WAS AN ATR 42 WHILE THE WAKE GENERATING ACFT WAS A B-747.

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.