Narrative:

Flight from agc to asg during day. Fuel stop at paducah, ky. Arriving paducah, thunderstorm in area. Deviated to hopkinsville for fuel. WX briefing at hopkinsville stated a line of scattered thunderstorms west of position, but several plane transitting. Departed hopkinsville on IFR flight plan and ATC vectored me toward hole in the line. Storm scope showing no activity, went IMC. Shortly after ward encountered severe turbulence. When turbulence prevented altitude and heading maintenance, declared emergency to get priority handling out of turbulence. ATC was so busy checking with several aircraft about their flight conditions that I had problems contacting them. After exiting the turbulence I cancelled the emergency status. ATC advised a large hole in the line south of my position and offered help if I wished to continue. I was VFR and clear of the clouds; therefore, I proceeded. ATC was very helpful vectoring around small cells. They advised a hole in the line with another plane in the hole at 14000' MSL, and a good ride. I asked ATC if there was a good place to land and wait out the storm. They advised that I was over tn and implied that there was no good spot. I was cleared to 13000', vectored to the hole that the other plane just used. My storm scope showed a clear path,, so I went IMC again. Prior to entering the cloud I throttled to maneuvering speed, dropped the gear and set approach flaps. Shortly after entering IMC, my storm scope lit up in all quadrants. I tried to reverse direction and contacted ATC for assistance. I encountered extremely severe turbulence. I could not control the aircraft. ATC said if I could hold on for a few more mi, I would be out of it, but could not give me any help in a direction to calm air. It didn't matter anyway as I could not have maintained a heading. The aircraft rose to over 17000' before being thrown out of the updraft. We were in a downdraft and descending nose down to about 6000', where I regained control still in IMC. I called ATC and requested the nearest airport to land. ATC vectored me to waverly, tn and I landed west/O problem. Suggestions to improve safety: 1) assume the WX to be worse than reported when a line of thunderstorms is present, even if reported as isolated. 2) never enter IMC with thunderstorms anywhere in the area. Cells generate too fast. 3) don't allow ATC to vector you into IMC with thunderstorms in the area. ATC was very helpful at times. This led me to believe their data and proceed IMC when I felt that I should stay VFR. 4) do not believe that if one aircraft has found a hole that it will stay for you no matter what ATC says. Check the accuracy of my storm scope more often. 6) despite what ATC suggests, land when thunderstorms are present in the area.

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Original NASA ASRS Text

Title: SMA CORP ACFT CONTINUES INTO KNOWN TSTM ACTIVITY WITH RADAR VECTORS. ENCOUNTERS SEVERE UP AND DOWNDRAFTS AND NO ACFT CTL. DECLARES EMERGENCY, LANDS.

Narrative: FLT FROM AGC TO ASG DURING DAY. FUEL STOP AT PADUCAH, KY. ARRIVING PADUCAH, TSTM IN AREA. DEVIATED TO HOPKINSVILLE FOR FUEL. WX BRIEFING AT HOPKINSVILLE STATED A LINE OF SCATTERED TSTMS W OF POS, BUT SEVERAL PLANE TRANSITTING. DEPARTED HOPKINSVILLE ON IFR FLT PLAN AND ATC VECTORED ME TOWARD HOLE IN THE LINE. STORM SCOPE SHOWING NO ACTIVITY, WENT IMC. SHORTLY AFTER WARD ENCOUNTERED SEVERE TURB. WHEN TURB PREVENTED ALT AND HDG MAINT, DECLARED EMER TO GET PRIORITY HANDLING OUT OF TURB. ATC WAS SO BUSY CHKING WITH SEVERAL ACFT ABOUT THEIR FLT CONDITIONS THAT I HAD PROBS CONTACTING THEM. AFTER EXITING THE TURB I CANCELLED THE EMER STATUS. ATC ADVISED A LARGE HOLE IN THE LINE S OF MY POS AND OFFERED HELP IF I WISHED TO CONTINUE. I WAS VFR AND CLR OF THE CLOUDS; THEREFORE, I PROCEEDED. ATC WAS VERY HELPFUL VECTORING AROUND SMALL CELLS. THEY ADVISED A HOLE IN THE LINE WITH ANOTHER PLANE IN THE HOLE AT 14000' MSL, AND A GOOD RIDE. I ASKED ATC IF THERE WAS A GOOD PLACE TO LAND AND WAIT OUT THE STORM. THEY ADVISED THAT I WAS OVER TN AND IMPLIED THAT THERE WAS NO GOOD SPOT. I WAS CLRED TO 13000', VECTORED TO THE HOLE THAT THE OTHER PLANE JUST USED. MY STORM SCOPE SHOWED A CLR PATH,, SO I WENT IMC AGAIN. PRIOR TO ENTERING THE CLOUD I THROTTLED TO MANEUVERING SPD, DROPPED THE GEAR AND SET APCH FLAPS. SHORTLY AFTER ENTERING IMC, MY STORM SCOPE LIT UP IN ALL QUADRANTS. I TRIED TO REVERSE DIRECTION AND CONTACTED ATC FOR ASSISTANCE. I ENCOUNTERED EXTREMELY SEVERE TURB. I COULD NOT CTL THE ACFT. ATC SAID IF I COULD HOLD ON FOR A FEW MORE MI, I WOULD BE OUT OF IT, BUT COULD NOT GIVE ME ANY HELP IN A DIRECTION TO CALM AIR. IT DIDN'T MATTER ANYWAY AS I COULD NOT HAVE MAINTAINED A HDG. THE ACFT ROSE TO OVER 17000' BEFORE BEING THROWN OUT OF THE UPDRAFT. WE WERE IN A DOWNDRAFT AND DSNDING NOSE DOWN TO ABOUT 6000', WHERE I REGAINED CTL STILL IN IMC. I CALLED ATC AND REQUESTED THE NEAREST ARPT TO LAND. ATC VECTORED ME TO WAVERLY, TN AND I LANDED W/O PROB. SUGGESTIONS TO IMPROVE SAFETY: 1) ASSUME THE WX TO BE WORSE THAN RPTED WHEN A LINE OF TSTMS IS PRESENT, EVEN IF RPTED AS ISOLATED. 2) NEVER ENTER IMC WITH TSTMS ANYWHERE IN THE AREA. CELLS GENERATE TOO FAST. 3) DON'T ALLOW ATC TO VECTOR YOU INTO IMC WITH TSTMS IN THE AREA. ATC WAS VERY HELPFUL AT TIMES. THIS LED ME TO BELIEVE THEIR DATA AND PROCEED IMC WHEN I FELT THAT I SHOULD STAY VFR. 4) DO NOT BELIEVE THAT IF ONE ACFT HAS FOUND A HOLE THAT IT WILL STAY FOR YOU NO MATTER WHAT ATC SAYS. CHK THE ACCURACY OF MY STORM SCOPE MORE OFTEN. 6) DESPITE WHAT ATC SUGGESTS, LAND WHEN TSTMS ARE PRESENT IN THE AREA.

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.