Narrative:

ATR-42 on a visual approach to jfk runway 4R. Following an airbus 340, we were approximately 8 NM behind (using TCASII to estimate) distance. We had the ILS tuned in and were flying above GS when we encountered the airbus wake. It was a violent roll. We were able to counteract it, however, it lasted only about 5 second. This encounter happened outside the heavy wake parameters. I fly the ATR- 42. It has a split elevator disconnect system. Whereby, if 1 side gets jammed you can disconnect and recover 1 side. During the wake encounter, it was rough enough to elicit a momentary (crew alert computer) 'warning' of a 'pitch (elevator) disconnect' for a split second, which means it came very close to splitting by itself. Luckily it did not. Conclusion: it appears that new generation aircraft are producing wakes that are greater than their predecessors and bear studying. Callback conversation with reporter revealed the following information: the reporter states that the crews are very aware of the effects of wake turbulence and they try to avoid it. In this case, they were 8 mi behind the A340 in their ATR-42 and offset to the localizer course when the wake was encountered. Part of the problem is that everyone is vectored at the same altitudes while in the pattern and on a calm day some of the wakes are very persistent. Another factor the reporter has noted is that in WX the controllers will have as little as 2 1/2 mi in-trail on the ILS approach. The reporter thinks that the newer technology aircraft have much more violent vortices than older aircraft. He also does not think that controllers are concerned about the problem. He feels that the heavy, new tech aircraft should be sent to a separate runway and from a separate pattern.

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Original NASA ASRS Text

Title: ATR 42 HAS MOMENTARY LOSS OF ACFT CTL DUE TO WAKE TURB FROM PRECEDING AIRBUS 340.

Narrative: ATR-42 ON A VISUAL APCH TO JFK RWY 4R. FOLLOWING AN AIRBUS 340, WE WERE APPROX 8 NM BEHIND (USING TCASII TO ESTIMATE) DISTANCE. WE HAD THE ILS TUNED IN AND WERE FLYING ABOVE GS WHEN WE ENCOUNTERED THE AIRBUS WAKE. IT WAS A VIOLENT ROLL. WE WERE ABLE TO COUNTERACT IT, HOWEVER, IT LASTED ONLY ABOUT 5 SECOND. THIS ENCOUNTER HAPPENED OUTSIDE THE HVY WAKE PARAMETERS. I FLY THE ATR- 42. IT HAS A SPLIT ELEVATOR DISCONNECT SYS. WHEREBY, IF 1 SIDE GETS JAMMED YOU CAN DISCONNECT AND RECOVER 1 SIDE. DURING THE WAKE ENCOUNTER, IT WAS ROUGH ENOUGH TO ELICIT A MOMENTARY (CREW ALERT COMPUTER) 'WARNING' OF A 'PITCH (ELEVATOR) DISCONNECT' FOR A SPLIT SECOND, WHICH MEANS IT CAME VERY CLOSE TO SPLITTING BY ITSELF. LUCKILY IT DID NOT. CONCLUSION: IT APPEARS THAT NEW GENERATION ACFT ARE PRODUCING WAKES THAT ARE GREATER THAN THEIR PREDECESSORS AND BEAR STUDYING. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATES THAT THE CREWS ARE VERY AWARE OF THE EFFECTS OF WAKE TURB AND THEY TRY TO AVOID IT. IN THIS CASE, THEY WERE 8 MI BEHIND THE A340 IN THEIR ATR-42 AND OFFSET TO THE LOC COURSE WHEN THE WAKE WAS ENCOUNTERED. PART OF THE PROB IS THAT EVERYONE IS VECTORED AT THE SAME ALTS WHILE IN THE PATTERN AND ON A CALM DAY SOME OF THE WAKES ARE VERY PERSISTENT. ANOTHER FACTOR THE RPTR HAS NOTED IS THAT IN WX THE CTLRS WILL HAVE AS LITTLE AS 2 1/2 MI IN-TRAIL ON THE ILS APCH. THE RPTR THINKS THAT THE NEWER TECHNOLOGY ACFT HAVE MUCH MORE VIOLENT VORTICES THAN OLDER ACFT. HE ALSO DOES NOT THINK THAT CTLRS ARE CONCERNED ABOUT THE PROB. HE FEELS THAT THE HVY, NEW TECH ACFT SHOULD BE SENT TO A SEPARATE RWY AND FROM A SEPARATE PATTERN.

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.