Narrative:

Air carrier X. I was about 2 mi northeast of smo on a heading of 070 degree at 7000 ft. We encountered wake turbulence from a 747 that was descending through my altitude at a distance of more than 5 mi. The first officer was the flying pilot. As the aircraft started to roll unctlably to the left, I took control of the aircraft. The aircraft continued to roll more than 90 degrees and then pitched straight down. I was able to recover back on our original heading at 6300 ft. I then declared an emergency and was immediately cleared to 5000 ft. I noticed we were not being handled as if we had declared an emergency. I then asked southern california approach if they were aware that we had declared an emergency. At that point, they asked if we still wanted to declare an emergency. Since everything seemed to be ok, I said `no'. Supplemental information from acn 269183: X told we were more than 5 mi in trail of the 747 descending through our altitude. As we entered the wake turbulence, the aircraft began an uncommanded roll to the left and I applied full right aileron but the aircraft continued to roll left. At this point, the captain came on the controls as well. The aircraft continued to roll left past 90 degrees to the horizon and the nose pitched down steeply. At this point, the aircraft was almost completely inverted and pitching nose down, we pushed forward on the yoke and the right aileron we had been holding in began to take effect. When the aircraft was wings level, we had surprisingly lost less than 1000 ft and rolled out close to our heading. Supplemental information from acn 269536: on downwind to lax, I had an SW3 5 mi behind a B747, descending to the same altitude at the same speed (170 KTS). The SW3 advised me that he was declaring an emergency due to wake turbulence. The pilot advised that his aircraft became inverted. After several xmissions, the pilot canceled the emergency.

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Original NASA ASRS Text

Title: ACR X LOSS OF ACFT CTL DUE TO WAKE TURB ENCOUNTER B747.

Narrative: ACR X. I WAS ABOUT 2 MI NE OF SMO ON A HDG OF 070 DEG AT 7000 FT. WE ENCOUNTERED WAKE TURB FROM A 747 THAT WAS DSNDING THROUGH MY ALT AT A DISTANCE OF MORE THAN 5 MI. THE FO WAS THE FLYING PLT. AS THE ACFT STARTED TO ROLL UNCTLABLY TO THE L, I TOOK CTL OF THE ACFT. THE ACFT CONTINUED TO ROLL MORE THAN 90 DEGS AND THEN PITCHED STRAIGHT DOWN. I WAS ABLE TO RECOVER BACK ON OUR ORIGINAL HDG AT 6300 FT. I THEN DECLARED AN EMER AND WAS IMMEDIATELY CLRED TO 5000 FT. I NOTICED WE WERE NOT BEING HANDLED AS IF WE HAD DECLARED AN EMER. I THEN ASKED SOUTHERN CALIFORNIA APCH IF THEY WERE AWARE THAT WE HAD DECLARED AN EMER. AT THAT POINT, THEY ASKED IF WE STILL WANTED TO DECLARE AN EMER. SINCE EVERYTHING SEEMED TO BE OK, I SAID `NO'. SUPPLEMENTAL INFO FROM ACN 269183: X TOLD WE WERE MORE THAN 5 MI IN TRAIL OF THE 747 DSNDING THROUGH OUR ALT. AS WE ENTERED THE WAKE TURB, THE ACFT BEGAN AN UNCOMMANDED ROLL TO THE L AND I APPLIED FULL R AILERON BUT THE ACFT CONTINUED TO ROLL L. AT THIS POINT, THE CAPT CAME ON THE CTLS AS WELL. THE ACFT CONTINUED TO ROLL L PAST 90 DEGS TO THE HORIZON AND THE NOSE PITCHED DOWN STEEPLY. AT THIS POINT, THE ACFT WAS ALMOST COMPLETELY INVERTED AND PITCHING NOSE DOWN, WE PUSHED FORWARD ON THE YOKE AND THE R AILERON WE HAD BEEN HOLDING IN BEGAN TO TAKE EFFECT. WHEN THE ACFT WAS WINGS LEVEL, WE HAD SURPRISINGLY LOST LESS THAN 1000 FT AND ROLLED OUT CLOSE TO OUR HDG. SUPPLEMENTAL INFO FROM ACN 269536: ON DOWNWIND TO LAX, I HAD AN SW3 5 MI BEHIND A B747, DSNDING TO THE SAME ALT AT THE SAME SPD (170 KTS). THE SW3 ADVISED ME THAT HE WAS DECLARING AN EMER DUE TO WAKE TURB. THE PLT ADVISED THAT HIS ACFT BECAME INVERTED. AFTER SEVERAL XMISSIONS, THE PLT CANCELED THE EMER.

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.