<< >> NASA ASRS Report 365045, April 1997

PIC of B757 on oceanic flight experiences severe turbulence at FL350. Declares an emergency and descends to FL280 for smoother ride. ZNY was notified of altitude deviation. Later clearance received for FL280. No off course deviation noted.

Attributes
ACN	365045
Time
Date	199704
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : zny
State Reference	NY
Altitude	msl bound lower : 28000 msl bound upper : 35000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zny
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other descent other other
Route In Use	enroute : atlantic enroute : other oceanic enroute airway : zny
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	365045
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter other non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance flight crew : declared emergency flight crew : exited adverse environment other
Consequence	Other
Supplementary
Primary Problem	Weather

Narrative:

CAT at FL350. Approximately AM05Z frequency/altitude, HF-6577-5550. ATC facility: HF-6577-5550, FL350, new york oceanic. Location: approximately 100 mi south of nutre on amber 30. Experienced light then moderate chop and had seat belt sign on and all flight attendants seated via interphone and PA. Soon thereafter, experienced moderate turbulence that was increasing in intensity. The turbulence became severe and I determined then that the safest course of action was to immediately descend to a lower altitude and simultaneously declared an emergency and notified ZNY and other aircraft via 121.5, HF radios and 130.55. Descended to FL280 and received new altitude clearance at FL280 for remainder of en route cruise altitude. No injuries and continued uneventfully to jfk. We had visual conditions during descent and TCASII and aircraft lights were being used as well as communication with other aircraft in the area.

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Original NASA ASRS Text

Title: PIC OF B757 ON OCEANIC FLT EXPERIENCES SEVERE TURB AT FL350. DECLARES AN EMER AND DSNDS TO FL280 FOR SMOOTHER RIDE. ZNY WAS NOTIFIED OF ALTDEV. LATER CLRNC RECEIVED FOR FL280. NO OFF COURSE DEV NOTED.

Narrative: CAT AT FL350. APPROX AM05Z FREQ/ALT, HF-6577-5550. ATC FACILITY: HF-6577-5550, FL350, NEW YORK OCEANIC. LOCATION: APPROX 100 MI S OF NUTRE ON AMBER 30. EXPERIENCED LIGHT THEN MODERATE CHOP AND HAD SEAT BELT SIGN ON AND ALL FLT ATTENDANTS SEATED VIA INTERPHONE AND PA. SOON THEREAFTER, EXPERIENCED MODERATE TURB THAT WAS INCREASING IN INTENSITY. THE TURB BECAME SEVERE AND I DETERMINED THEN THAT THE SAFEST COURSE OF ACTION WAS TO IMMEDIATELY DSND TO A LOWER ALT AND SIMULTANEOUSLY DECLARED AN EMER AND NOTIFIED ZNY AND OTHER ACFT VIA 121.5, HF RADIOS AND 130.55. DSNDED TO FL280 AND RECEIVED NEW ALT CLRNC AT FL280 FOR REMAINDER OF ENRTE CRUISE ALT. NO INJURIES AND CONTINUED UNEVENTFULLY TO JFK. WE HAD VISUAL CONDITIONS DURING DSCNT AND TCASII AND ACFT LIGHTS WERE BEING USED AS WELL AS COM WITH OTHER ACFT IN THE AREA.

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.