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

Date: 1994-04 · Aircraft: SA-226 TC Metro II

Anomalies: deviation-altitude-excursion-from-assigned-altitude|inflight-event-encounter-loss-of-aircraft-control|inflight-event-encounter-other-unknown|other-unspecified

Synopsis

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.

Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.