B737-700 crew deviating for WX; returned to original course without coordinating with ATC.

Attributes
ACN	691094
Time
Date	200603
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : ont.airport
State Reference	CA
Altitude	msl single value : 6000
Environment
Flight Conditions	IMC
Weather Elements	Turbulence Thunderstorm Ice
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sct.tracon
Operator	common carrier : air carrier
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 220 flight time total : 15000 flight time type : 10000
ASRS Report	691094
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 210 flight time total : 5500 flight time type : 1100
ASRS Report	691278
Events
Anomaly	other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance flight crew : returned to original clearance
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Weather ATC Human Performance Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

During our approach into ont; socal cleared us direct to petis. However; between our position and petis; there were some cells we wanted to deviate around. We asked for 15 degrees to the right (north) of course which were approved by ATC. When we approached a gap between 2 cells that would allow us to go back towards petis; we started to make the turn. ATC promptly vectored us back to the north and told us we needed to coordination the turn back to petis before we did it as there was potential of conflict with another IFR aircraft. The rest of the approach was uneventful.

Original NASA ASRS Text

Title: B737-700 CREW DEVIATING FOR WX; RETURNED TO ORIGINAL COURSE WITHOUT COORDINATING WITH ATC.

Narrative: DURING OUR APCH INTO ONT; SOCAL CLRED US DIRECT TO PETIS. HOWEVER; BTWN OUR POS AND PETIS; THERE WERE SOME CELLS WE WANTED TO DEVIATE AROUND. WE ASKED FOR 15 DEGS TO THE R (N) OF COURSE WHICH WERE APPROVED BY ATC. WHEN WE APCHED A GAP BTWN 2 CELLS THAT WOULD ALLOW US TO GO BACK TOWARDS PETIS; WE STARTED TO MAKE THE TURN. ATC PROMPTLY VECTORED US BACK TO THE N AND TOLD US WE NEEDED TO COORD THE TURN BACK TO PETIS BEFORE WE DID IT AS THERE WAS POTENTIAL OF CONFLICT WITH ANOTHER IFR ACFT. THE REST OF THE APCH WAS UNEVENTFUL.

Data retrieved from NASA's ASRS site as of January 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.