MD11 flight crew en route from lax to hnl deviated around WX without prior approval from ATC.

Attributes
ACN	636943
Time
Date	200411
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	intersection : duffe
State Reference	US
Altitude	msl single value : 34000
Environment
Flight Conditions	IMC
Weather Elements	Thunderstorm
Light	Night
Aircraft 1
Controlling Facilities	artcc : zoa.artcc
Operator	common carrier : air carrier
Make Model Name	MD-11
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : level
Route In Use	enroute : pacific
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 20000 flight time type : 2000
ASRS Report	636943
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	inflight encounter : weather non adherence : clearance other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	flight crew : took precautionary avoidance action
Supplementary
Problem Areas	Weather
Primary Problem	Weather

Narrative:

En route from lax to hnl on R576 just prior to duffe intersection we observed a large cell on the center of the airway. I called center and asked for a 10 mi deviation to the left. 5 mins later center came back and said that the deviation was disapproved. I then asked for a deviation to the right. A few mins later center said that deviation was disapproved. I then exercised my captain's authority/authorized and told center that we were deviating 10 mi right off course due to a large cell on the center of the airway. They acknowledged my call and gave no explanation for my previous request being denied. We observed TCASII traffic 2000 ft below us deviating to the left and no traffic to the right. We avoided the WX and corrected to course as soon as we were clear of the WX.

Original NASA ASRS Text

Title: MD11 FLT CREW ENRTE FROM LAX TO HNL DEVIATED AROUND WX WITHOUT PRIOR APPROVAL FROM ATC.

Narrative: ENRTE FROM LAX TO HNL ON R576 JUST PRIOR TO DUFFE INTXN WE OBSERVED A LARGE CELL ON THE CTR OF THE AIRWAY. I CALLED CENTER AND ASKED FOR A 10 MI DEV TO THE L. 5 MINS LATER CENTER CAME BACK AND SAID THAT THE DEV WAS DISAPPROVED. I THEN ASKED FOR A DEV TO THE R. A FEW MINS LATER CENTER SAID THAT DEV WAS DISAPPROVED. I THEN EXERCISED MY CAPT'S AUTH AND TOLD CENTER THAT WE WERE DEVIATING 10 MI R OFF COURSE DUE TO A LARGE CELL ON THE CTR OF THE AIRWAY. THEY ACKNOWLEDGED MY CALL AND GAVE NO EXPLANATION FOR MY PREVIOUS REQUEST BEING DENIED. WE OBSERVED TCASII TFC 2000 FT BELOW US DEVIATING TO THE L AND NO TFC TO THE R. WE AVOIDED THE WX AND CORRECTED TO COURSE AS SOON AS WE WERE CLR OF THE WX.

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.