<< >> NASA ASRS Report 1420341, January 2017

B737 captain reported deviating around an area of reported severe turbulence on a trans-pacific flight without ATC approval.

Attributes
ACN	1420341
Time
Date	201701
Local Time Of Day	0001-0600
Place
Locale Reference	KZAK.ARTCC
State Reference	HI
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	B737 Next Generation Undifferentiated
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Route In Use	Oceanic
Flight Plan	IFR
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Type 1733
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Track / Heading All Types

Narrative:

Enroute [while over the pacific ocean] I was notified by ATC and dispatch of a SIGMET that had a report of observed severe turbulence on our route and altitude. I attempted for one hour to get a new route north of the area or lower altitude below the reported/forecast area of turbulence. Approaching fix gitle after ATC was only willing to let me offset 50 NM south into the forecast area to get a lower altitude and dispatch was unable to get ATC to change my route; I [exercised my captain's authority]. We turned 45 degrees north and offset 15 NM then descended to FL270. Then we returned to our route. FL270 was below the SIGMET area. I prepped the cabin for turbulence while we passed the area just in case. The flight was normal and ATC and dispatch were advised.

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Original NASA ASRS Text

Title: B737 Captain reported deviating around an area of reported severe turbulence on a trans-Pacific flight without ATC approval.

Narrative: Enroute [while over the Pacific Ocean] I was notified by ATC and Dispatch of a SIGMET that had a report of Observed Severe Turbulence on our route and altitude. I attempted for one hour to get a new route north of the area or lower altitude below the reported/forecast area of turbulence. Approaching fix GITLE after ATC was only willing to let me offset 50 NM south into the forecast area to get a lower altitude and Dispatch was unable to get ATC to change my route; I [exercised my Captain's authority]. We turned 45 degrees north and offset 15 NM then descended to FL270. Then we returned to our route. FL270 was below the SIGMET area. I prepped the cabin for turbulence while we passed the area just in case. The flight was normal and ATC and Dispatch were advised.

Data retrieved from NASA's ASRS site 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.