Narrative:

Passed over vtu VOR inbound on sadde 6 arrival. Instructed by socal approach to 'proceed direct santa monica airport, caution wake turbulence in trail of heavy B747 6 mi.' we were then cleared to descend to 10000 ft MSL, we reported both the B747 and lax airport in sight. Upon arriving at 10000 ft, we felt turbulence in a series of bumps (approximately 3-6) and then aircraft took a roll of 60 degrees to starboard, the first officer corrected, and aircraft then rolled 45 degrees to the left. We took several smaller rolls in each direction before the aircraft stabilized. WX was unusually clear (no smog) for the los angeles basin. Both the first officer and myself had flown into lax many times and had developed the habit of always staying above (in altitude) any heavy aircraft we were following. We were both surprised to hit wake turbulence that far behind a heavy. Callback conversation with reporter revealed the following information: this reporter was flying a beech 1900D and he was behind a B747. The WX was very clear and calm with visibility around 100 mi and no wind. He thought that 6 mi was plenty of distance behind the B747, but as he approached smo at 10000 ft he suddenly rolled to the right. The first officer (flying) put in full left aileron, but the bank angle reached 60 degrees anyway. Then the aircraft rolled rapidly to the left to 45 degrees again with the first officer attempting to stop the roll with full opposite aileron. After this, several lesser rolling moments were encountered. The approach controller was informed. During the approach the flight crew stayed high on the GS and avoided further encounters.

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Original NASA ASRS Text

Title: THE FLC OF A BEECH 1900D HITS THE WAKE OF A B747 THAT WAS 6 MI AHEAD OF THEM AT 10000 FT. THE BEECH 1900D ROLLS SEVERAL TIMES, INCLUDING A BANK ANGLE OF 60 DEGS FOR 1 ROLL WITH FULL OPPOSITE AILERON APPLIED.

Narrative: PASSED OVER VTU VOR INBOUND ON SADDE 6 ARR. INSTRUCTED BY SOCAL APCH TO 'PROCEED DIRECT SANTA MONICA ARPT, CAUTION WAKE TURB IN TRAIL OF HVY B747 6 MI.' WE WERE THEN CLRED TO DSND TO 10000 FT MSL, WE RPTED BOTH THE B747 AND LAX ARPT IN SIGHT. UPON ARRIVING AT 10000 FT, WE FELT TURB IN A SERIES OF BUMPS (APPROX 3-6) AND THEN ACFT TOOK A ROLL OF 60 DEGS TO STARBOARD, THE FO CORRECTED, AND ACFT THEN ROLLED 45 DEGS TO THE L. WE TOOK SEVERAL SMALLER ROLLS IN EACH DIRECTION BEFORE THE ACFT STABILIZED. WX WAS UNUSUALLY CLR (NO SMOG) FOR THE LOS ANGELES BASIN. BOTH THE FO AND MYSELF HAD FLOWN INTO LAX MANY TIMES AND HAD DEVELOPED THE HABIT OF ALWAYS STAYING ABOVE (IN ALT) ANY HVY ACFT WE WERE FOLLOWING. WE WERE BOTH SURPRISED TO HIT WAKE TURB THAT FAR BEHIND A HVY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THIS RPTR WAS FLYING A BEECH 1900D AND HE WAS BEHIND A B747. THE WX WAS VERY CLR AND CALM WITH VISIBILITY AROUND 100 MI AND NO WIND. HE THOUGHT THAT 6 MI WAS PLENTY OF DISTANCE BEHIND THE B747, BUT AS HE APCHED SMO AT 10000 FT HE SUDDENLY ROLLED TO THE R. THE FO (FLYING) PUT IN FULL L AILERON, BUT THE BANK ANGLE REACHED 60 DEGS ANYWAY. THEN THE ACFT ROLLED RAPIDLY TO THE L TO 45 DEGS AGAIN WITH THE FO ATTEMPTING TO STOP THE ROLL WITH FULL OPPOSITE AILERON. AFTER THIS, SEVERAL LESSER ROLLING MOMENTS WERE ENCOUNTERED. THE APCH CTLR WAS INFORMED. DURING THE APCH THE FLC STAYED HIGH ON THE GS AND AVOIDED FURTHER ENCOUNTERS.

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.