Narrative:

We departed savannah, GA, bound for freeport, bahamas. Sav tower had us fly runway heading. Sav departure cleared us direct freeport. The stratus layer over sav was easily topped and we flew comfortably at 6000 ft. ZJX cleared us to 10000 ft but took exception to our traversing the warning area. We were directed to ormond beach and vero beach VOR's. This southerly heading put us into the building cumulus. I mostly fly in an area where cumulus build-ups are common but slow to ascend. These are things I always avoid if at all possible. The ride became increasingly choppy, leading to moderate turbulence. We flew in and out of some lower cumulus build-ups but managed to avoid the big towers. About 10 mi ahead was a line of low cumulus towers, several thousand ft below me. In expectation of topping the line, I asked for and received clearance to 16000 ft. By now passenger and I were using supplemental oxygen. The closer I got to the cumulus tops the higher they seemed to be. It soon became obvious that I would not clear the tops. We were severely bounced around inside the clouds. Upon exiting the build-up, we could see more ahead, but clear air appeared off to our right. I asked for and received clearance to deviate 10-20 degrees to the right. At this time the frequency was saturated with pilots deviating somewhere. The controller was doing a marvelous job of keeping the aluminum pieces apart. I believe we were talking to ZMA at this time, near melbourne VOR. The build-ups were so rapid that I could see the tops rolling and climbing. I have never seen so rapid a rise of cloud tops before. Remembering the turbulence of a few mins earlier, I deviated farther to the right than the controller thought was appropriate. It was probably 30-35 degrees. This prompted an on-air rebuke that was deserved. Turning back on course, we entered another build-up that contained moderate to severe turbulence. I had to disconnect the autoplt and try to remain merely level. The ride was so rough that my passenger had a bruise on the knee from the control wheel and my back was in pain for several days after landing. Immediately upon exiting that build-up we were given an amended clearance to an unfamiliar intersection called jakel, close to freeport. I quickly hit the flight director, altitude hold, heading bug and autoplt 'on' buttons. Then my passenger and I tried to find the maps that were now scattered all over the airplane. Unbeknown to me, I had hit the altitude hold button twice (or once insufficiently). Consequently, during the search for the maps and intersection, we lost 2000 ft of altitude. The controller was again understandably irate. By this time we were in clear off-shore air again and stabilized on BR62V headed toward jakel. The flight continued uneventfully on to freeport. We returned to michigan a week later. There are several things I will remember from this trip. Always be prepared for the unexpected. Cumulus burlaps are survivable, and not an excuse for excessive deviation (emergency authority/authorized excepted). When engaging the autoplt make sure the heading and altitude lock lights are lit. Communicate with the controller and relay any additional deviations you may require.

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Original NASA ASRS Text

Title: THE PLT OF AN M20P DEVIATED FROM ASSIGNED HDG AND ALT.

Narrative: WE DEPARTED SAVANNAH, GA, BOUND FOR FREEPORT, BAHAMAS. SAV TWR HAD US FLY RWY HDG. SAV DEP CLRED US DIRECT FREEPORT. THE STRATUS LAYER OVER SAV WAS EASILY TOPPED AND WE FLEW COMFORTABLY AT 6000 FT. ZJX CLRED US TO 10000 FT BUT TOOK EXCEPTION TO OUR TRAVERSING THE WARNING AREA. WE WERE DIRECTED TO ORMOND BEACH AND VERO BEACH VOR'S. THIS SOUTHERLY HDG PUT US INTO THE BUILDING CUMULUS. I MOSTLY FLY IN AN AREA WHERE CUMULUS BUILD-UPS ARE COMMON BUT SLOW TO ASCEND. THESE ARE THINGS I ALWAYS AVOID IF AT ALL POSSIBLE. THE RIDE BECAME INCREASINGLY CHOPPY, LEADING TO MODERATE TURB. WE FLEW IN AND OUT OF SOME LOWER CUMULUS BUILD-UPS BUT MANAGED TO AVOID THE BIG TWRS. ABOUT 10 MI AHEAD WAS A LINE OF LOW CUMULUS TWRS, SEVERAL THOUSAND FT BELOW ME. IN EXPECTATION OF TOPPING THE LINE, I ASKED FOR AND RECEIVED CLRNC TO 16000 FT. BY NOW PAX AND I WERE USING SUPPLEMENTAL OXYGEN. THE CLOSER I GOT TO THE CUMULUS TOPS THE HIGHER THEY SEEMED TO BE. IT SOON BECAME OBVIOUS THAT I WOULD NOT CLR THE TOPS. WE WERE SEVERELY BOUNCED AROUND INSIDE THE CLOUDS. UPON EXITING THE BUILD-UP, WE COULD SEE MORE AHEAD, BUT CLR AIR APPEARED OFF TO OUR R. I ASKED FOR AND RECEIVED CLRNC TO DEVIATE 10-20 DEGS TO THE R. AT THIS TIME THE FREQ WAS SATURATED WITH PLTS DEVIATING SOMEWHERE. THE CTLR WAS DOING A MARVELOUS JOB OF KEEPING THE ALUMINUM PIECES APART. I BELIEVE WE WERE TALKING TO ZMA AT THIS TIME, NEAR MELBOURNE VOR. THE BUILD-UPS WERE SO RAPID THAT I COULD SEE THE TOPS ROLLING AND CLBING. I HAVE NEVER SEEN SO RAPID A RISE OF CLOUD TOPS BEFORE. REMEMBERING THE TURB OF A FEW MINS EARLIER, I DEVIATED FARTHER TO THE R THAN THE CTLR THOUGHT WAS APPROPRIATE. IT WAS PROBABLY 30-35 DEGS. THIS PROMPTED AN ON-AIR REBUKE THAT WAS DESERVED. TURNING BACK ON COURSE, WE ENTERED ANOTHER BUILD-UP THAT CONTAINED MODERATE TO SEVERE TURB. I HAD TO DISCONNECT THE AUTOPLT AND TRY TO REMAIN MERELY LEVEL. THE RIDE WAS SO ROUGH THAT MY PAX HAD A BRUISE ON THE KNEE FROM THE CTL WHEEL AND MY BACK WAS IN PAIN FOR SEVERAL DAYS AFTER LNDG. IMMEDIATELY UPON EXITING THAT BUILD-UP WE WERE GIVEN AN AMENDED CLRNC TO AN UNFAMILIAR INTXN CALLED JAKEL, CLOSE TO FREEPORT. I QUICKLY HIT THE FLT DIRECTOR, ALT HOLD, HDG BUG AND AUTOPLT 'ON' BUTTONS. THEN MY PAX AND I TRIED TO FIND THE MAPS THAT WERE NOW SCATTERED ALL OVER THE AIRPLANE. UNBEKNOWN TO ME, I HAD HIT THE ALT HOLD BUTTON TWICE (OR ONCE INSUFFICIENTLY). CONSEQUENTLY, DURING THE SEARCH FOR THE MAPS AND INTXN, WE LOST 2000 FT OF ALT. THE CTLR WAS AGAIN UNDERSTANDABLY IRATE. BY THIS TIME WE WERE IN CLR OFF-SHORE AIR AGAIN AND STABILIZED ON BR62V HEADED TOWARD JAKEL. THE FLT CONTINUED UNEVENTFULLY ON TO FREEPORT. WE RETURNED TO MICHIGAN A WK LATER. THERE ARE SEVERAL THINGS I WILL REMEMBER FROM THIS TRIP. ALWAYS BE PREPARED FOR THE UNEXPECTED. CUMULUS BURLAPS ARE SURVIVABLE, AND NOT AN EXCUSE FOR EXCESSIVE DEV (EMER AUTH EXCEPTED). WHEN ENGAGING THE AUTOPLT MAKE SURE THE HDG AND ALT LOCK LIGHTS ARE LIT. COMMUNICATE WITH THE CTLR AND RELAY ANY ADDITIONAL DEVS YOU MAY REQUIRE.

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.