B757 flight crew encounters severe turbulence east bound at FL370. No injuries occur; however crew e...

Attributes
ACN	816581
Time
Date	200812
Local Time Of Day	0001 To 0600
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 37000
Environment
Weather Elements	Turbulence
Aircraft 1
Controlling Facilities	artcc : zzz.artcc
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Route In Use	enroute airway : zzz.airway
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 240 flight time total : 14500 flight time type : 4000
ASRS Report	816581
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 160 flight time total : 12000 flight time type : 3600
ASRS Report	816588
Events
Anomaly	inflight encounter : turbulence other anomaly other anomaly
Independent Detector	other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : diverted to another airport flight crew : exited adverse environment flight crew : declared emergency
Supplementary
Problem Areas	Weather
Primary Problem	Weather

Narrative:

During cruise; light to moderate chop; light mountain wave; +/- .01 mach; we sat the passengers and told the flight attendants they may need to sit shortly. Approaching approximately 40 mile west of xxxxx; mountain wave became moderate (+/- .02 mach and ivsi +/-700 FPM) with moderate chop and we sat the flight attendants via interphone; followed up with PA of 'flight attendants be seated immediately.' within a very short time; the ivsi swung from +/-1;500 FPM and our .79 mach increased to near barber pole .84 mach. The autopilot kicked off during a pitch-up of about 8 degrees; followed by a bank of 15-20 degrees. Pilots took control of the aircraft and requested immediate descent due to the now 'severe turbulence.' ATC cleared flight to FL330 and the crew descended in moderate chop. Cabin crew confirmed all passengers were seated and crew was all safe in their seats as well. At FL330 over xxxxx; a few minutes later; a pair of severe jolts was encountered. During this encounter; the captain was on SELCAL with dispatch and maintenance to determine best course of action; i.e.; continue to ZZZ2 or land ZZZ3 where the flight might recover and continue with another aircraft. Both pilots with coordination from dispatch and ATC declared an emergency and got a clearance to ZZZ3. The autopilot was reengaged after it was determined the aircraft could be trimmed and flown in a normal manner. An uneventful approach and landing followed with taxi to the gate.

Original NASA ASRS Text

Title: B757 flight crew encounters severe turbulence east bound at FL370. No injuries occur; however crew elects to divert for maintenance inspection.

Narrative: During cruise; light to moderate chop; light mountain wave; +/- .01 Mach; we sat the passengers and told the Flight Attendants they may need to sit shortly. Approaching approximately 40 mile west of XXXXX; mountain wave became moderate (+/- .02 Mach and IVSI +/-700 FPM) with moderate chop and we sat the Flight Attendants via interphone; followed up with PA of 'Flight Attendants be seated immediately.' Within a very short time; the IVSI swung from +/-1;500 FPM and our .79 Mach increased to near barber pole .84 Mach. The autopilot kicked off during a pitch-up of about 8 degrees; followed by a bank of 15-20 degrees. Pilots took control of the aircraft and requested immediate descent due to the now 'Severe Turbulence.' ATC cleared flight to FL330 and the crew descended in moderate chop. Cabin crew confirmed all passengers were seated and crew was all safe in their seats as well. At FL330 over XXXXX; a few minutes later; a pair of severe jolts was encountered. During this encounter; the Captain was on SELCAL with Dispatch and Maintenance to determine best course of action; i.e.; continue to ZZZ2 or land ZZZ3 where the flight might recover and continue with another aircraft. Both Pilots with coordination from Dispatch and ATC declared an emergency and got a clearance to ZZZ3. The autopilot was reengaged after it was determined the aircraft could be trimmed and flown in a normal manner. An uneventful approach and landing followed with taxi to the gate.

Data retrieved from NASA's ASRS site as of May 2009 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.