Narrative:

We were at 9000' in clouds 25 south of the myrtle beach VOR on a heading approved by ATC we had asked for to deviate east of V1 for heavy WX. We had no airborne WX radar but had specific reports from both the ground controllers and 1 other aircraft of heavy WX 10-15 northeast of grand stand/north myrtle beach (35-40 mi) from our position. The reported WX at grand stand was 80 overcast r- at the time. We elected to discontinue the flight and land at grand stand and asked for descent to 7000. We were told not able by the ground controller and we were aware of 2 other aircraft IFR both in excess of 10 NM to the north of grand stand. At that point we encountered moderate to severe turbulence and elected to make an immediate 180 degree turn to the east while asking grand stand approach for deviation and lower. Approximately 90 degree of turn, grand stand cleared us to 5000 and authorized a turn of 180 degree to remain clear of the turbulence. We landed after a visual approach at grand stand without further problems. We feel we had reliable information with regard to the heavy WX 35 mi to our north and west (from both ground and flight information) but were unwilling to continue into turbulence without any radar, storm scope and felt the safest avenue was a 180 degree turn given approach would not authorize lower. With hindsight, had we offered grand stand approach the option of lower or a deviation/180 degree/etc, they might have cleared us for a deviation (not being able to give us lower) immediately as opposed to after we had initiated the turn ourselves and then requesting it during the turn. We are unaware if our turn caused the approach facility to reroute after traffic although we did not hear any rerouting on the frequency and approach at no time advised us of any problems our turn had caused.

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Original NASA ASRS Text

Title: PLT OF SMA ENCOUNTERS SEVERE TURBULENCE IN CRUISE. WHEN UNABLE TO GET LOWER ALT FROM CRE APCH CTLR, HE EXERCISES HIS COMMAND AUTHORITY BY MAKING AN UNAUTHORIZED 180 DEG TURN.

Narrative: WE WERE AT 9000' IN CLOUDS 25 S OF THE MYRTLE BEACH VOR ON A HDG APPROVED BY ATC WE HAD ASKED FOR TO DEVIATE E OF V1 FOR HEAVY WX. WE HAD NO AIRBORNE WX RADAR BUT HAD SPECIFIC REPORTS FROM BOTH THE GND CTLRS AND 1 OTHER ACFT OF HEAVY WX 10-15 NE OF GRAND STAND/N MYRTLE BEACH (35-40 MI) FROM OUR POSITION. THE REPORTED WX AT GRAND STAND WAS 80 OVERCAST R- AT THE TIME. WE ELECTED TO DISCONTINUE THE FLT AND LAND AT GRAND STAND AND ASKED FOR DSCNT TO 7000. WE WERE TOLD NOT ABLE BY THE GND CTLR AND WE WERE AWARE OF 2 OTHER ACFT IFR BOTH IN EXCESS OF 10 NM TO THE N OF GRAND STAND. AT THAT POINT WE ENCOUNTERED MODERATE TO SEVERE TURBULENCE AND ELECTED TO MAKE AN IMMEDIATE 180 DEG TURN TO THE E WHILE ASKING GRAND STAND APCH FOR DEVIATION AND LOWER. APPROX 90 DEG OF TURN, GRAND STAND CLRED US TO 5000 AND AUTHORIZED A TURN OF 180 DEG TO REMAIN CLEAR OF THE TURBULENCE. WE LANDED AFTER A VISUAL APCH AT GRAND STAND WITHOUT FURTHER PROBLEMS. WE FEEL WE HAD RELIABLE INFO WITH REGARD TO THE HEAVY WX 35 MI TO OUR N AND W (FROM BOTH GND AND FLT INFO) BUT WERE UNWILLING TO CONTINUE INTO TURBULENCE WITHOUT ANY RADAR, STORM SCOPE AND FELT THE SAFEST AVENUE WAS A 180 DEG TURN GIVEN APCH WOULD NOT AUTHORIZE LOWER. WITH HINDSIGHT, HAD WE OFFERED GRAND STAND APCH THE OPTION OF LOWER OR A DEVIATION/180 DEG/ETC, THEY MIGHT HAVE CLRED US FOR A DEVIATION (NOT BEING ABLE TO GIVE US LOWER) IMMEDIATELY AS OPPOSED TO AFTER WE HAD INITIATED THE TURN OURSELVES AND THEN REQUESTING IT DURING THE TURN. WE ARE UNAWARE IF OUR TURN CAUSED THE APCH FAC TO REROUTE AFTER TFC ALTHOUGH WE DID NOT HEAR ANY REROUTING ON THE FREQ AND APCH AT NO TIME ADVISED US OF ANY PROBLEMS OUR TURN HAD CAUSED.

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.