Narrative:

During arrival at stl, we were coming down the rivers arrival toward some heavy precipitation. As we approached the precipitation area, we saw numerous lightning flashes in the clouds immediately in front of us. I was unable to get a word in to ATC requesting deviation. I told the first officer to turn right to avoid the storm cloud. As the turn was initiated, I was able to notify ATC about the deviation. We had barely strayed from course when ATC was notified. We turned back parallel to the arrival as soon as we were clear of the WX. ATC did comment about turning without permission, but no other comments were made. I felt that the situation required immediate action to guarantee the safety of the aircraft and passenger.

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Original NASA ASRS Text

Title: MD80 CREW ARRIVING STL DEVIATED AROUND A TSTM, BUT WERE UNABLE TO OBTAIN CLRNC FROM ATC, BECAUSE OF FREQ CONGESTION.

Narrative: DURING ARR AT STL, WE WERE COMING DOWN THE RIVERS ARR TOWARD SOME HEAVY PRECIP. AS WE APCHED THE PRECIP AREA, WE SAW NUMEROUS LIGHTNING FLASHES IN THE CLOUDS IMMEDIATELY IN FRONT OF US. I WAS UNABLE TO GET A WORD IN TO ATC REQUESTING DEVIATION. I TOLD THE FO TO TURN R TO AVOID THE STORM CLOUD. AS THE TURN WAS INITIATED, I WAS ABLE TO NOTIFY ATC ABOUT THE DEVIATION. WE HAD BARELY STRAYED FROM COURSE WHEN ATC WAS NOTIFIED. WE TURNED BACK PARALLEL TO THE ARR AS SOON AS WE WERE CLR OF THE WX. ATC DID COMMENT ABOUT TURNING WITHOUT PERMISSION, BUT NO OTHER COMMENTS WERE MADE. I FELT THAT THE SIT REQUIRED IMMEDIATE ACTION TO GUARANTEE THE SAFETY OF THE ACFT AND PAX.

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.