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Aircraft receives light wake turbulence from preceding B-757. Flight crew initially thinks the turbulence is normal until they are aware they are following a B-757 in trail, 15 mi ahead. What surprises the flight crew is that they get 10-15 degree roll when they are so far behind the B-757.
| Attributes | |
| ACN | 306395 |
| Time | |
| Date | 199505 |
| Day | Wed |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : isp |
| State Reference | NY |
| Altitude | msl bound lower : 21000 msl bound upper : 21000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zny artcc : clt |
| Operator | common carrier : air carrier |
| Make Model Name | B737-300 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | descent other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | B757 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | descent other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : flight engineer |
| Experience | flight time last 90 days : 160 flight time total : 13000 flight time type : 4000 |
| ASRS Report | 306395 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument |
| Events | |
| Anomaly | inflight encounter other |
| Independent Detector | other flight crewa |
| Resolutory Action | none taken : insufficient time none taken : unable |
| Consequence | Other |
| Miss Distance | horizontal : 90000 |
| Supplementary | |
| Air Traffic Incident | other |
Narrative:
ATC clearance to descend to FL210 for clearance to isp. Following an air carrier B757 at FL210 as indicated on TCASII 15 mi ahead at 12 O'clock. I called ZNY about moderate chop at FL210 and turned on seat belt sign when the bumps started. Both pilots realized after my call that it was not clear air turbulence but wake turbulence. The vertical bumps were similar to moderate chop, but at the same time we received roll inputs that were approximately 10-15 percent left and right. The incident lasted only a few seconds and the autoplt did not disengage. No injuries to passenger or crew. We considered the upset as 'light.' the air carrier was inbound to jfk and was probably being set up for a VOR 13 approach. We continued to isp without incident. Winds aloft, although available at the time, were not recorded.
Original NASA ASRS Text
Title: ACFT RECEIVES LIGHT WAKE TURB FROM PRECEDING B-757. FLC INITIALLY THINKS THE TURB IS NORMAL UNTIL THEY ARE AWARE THEY ARE FOLLOWING A B-757 IN TRAIL, 15 MI AHEAD. WHAT SURPRISES THE FLC IS THAT THEY GET 10-15 DEG ROLL WHEN THEY ARE SO FAR BEHIND THE B-757.
Narrative: ATC CLRNC TO DSND TO FL210 FOR CLRNC TO ISP. FOLLOWING AN ACR B757 AT FL210 AS INDICATED ON TCASII 15 MI AHEAD AT 12 O'CLOCK. I CALLED ZNY ABOUT MODERATE CHOP AT FL210 AND TURNED ON SEAT BELT SIGN WHEN THE BUMPS STARTED. BOTH PLTS REALIZED AFTER MY CALL THAT IT WAS NOT CLR AIR TURB BUT WAKE TURB. THE VERT BUMPS WERE SIMILAR TO MODERATE CHOP, BUT AT THE SAME TIME WE RECEIVED ROLL INPUTS THAT WERE APPROX 10-15 PERCENT L AND R. THE INCIDENT LASTED ONLY A FEW SECONDS AND THE AUTOPLT DID NOT DISENGAGE. NO INJURIES TO PAX OR CREW. WE CONSIDERED THE UPSET AS 'LIGHT.' THE ACR WAS INBOUND TO JFK AND WAS PROBABLY BEING SET UP FOR A VOR 13 APCH. WE CONTINUED TO ISP WITHOUT INCIDENT. WINDS ALOFT, ALTHOUGH AVAILABLE AT THE TIME, WERE NOT RECORDED.
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.