MLG ELECTRONIC COMPASS INDICATORS GIVE ERRATIC INDICATIONS DURING DSCNT DUE TO POSSIBLE PAX OPERATED 'CD' PORTABLE PLAYER.

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APCHING FUZZY INTXN WHILE INBOUND ON THE FUZZY 3 ARR INTO LAS; FO'S FLT INSTS; IE; HSI AND RMI COMPASS CARDS; SHOWED INDICATIONS OF POSSIBLE ELECTRONIC INTERFERENCE. THE FOLLOWING IS THE DETAILS OF THE OCCURRENCE: AUTOPLT 'B' IN CMD MODE WITH HDG SELECT MODE AND ALT HOLD MODE ENGAGED. JUST PRIOR TO REACHING FUZZY INTXN; ACFT MADE AN UNCOMMANDED 15 DEG L TURN. FLC CHKED AUTOPLT STATUS TO DETERMINE IF VOR LOC MODE WAS ARMED; IT WASN'T. ACFT BEGAN A R TURN TO ORIGINAL HDG WHEN FO INTERCEDED AND TURNED ACFT BACK TO THE L TO INTERCEPT BLD VOR 269 DEG RADIAL INBOUND. DSNDING THROUGH APPROX 14000 FT; FO OBSERVED THAT BOTH HIS HSI AND RMI COMPASS CARDS WHERE SLEWING PLUS OR MINUS 70 DEGS EITHER SIDE OF HDG SELECTED (089 DEGS). WITH AUTOPLT STILL IN CMD MODE; ACFT MADE SHALLOW BANKING MOTIONS AS IT INITIATED BOTH L AND R TURNS. ON NEXT OCCURRENCE; FO ENGAGED CWS MODE ON AUTOPLT TO ELIMINATE DUTCH ROLL CAUSED BY AUTOPLT ANOMALY. ON NEXT OCCURRENCE; WITH AUTOPLT IN CWS AND FO'S HSI AND RMI COMPASS CARDS RANDOMLY SLEWING L AND R OF HDG SELECTED; ACFT REMAINED ON DESIRED HDG. ON NEXT OCCURRENCE; IT WAS DETERMINED THAT NEITHER THE CAPT'S HSI OR RMI COMPASS CARDS WERE BEING AFFECTED. FLC SUSPECTED POSSIBLE ELECTRONIC INTERFERENCE. CAPT REQUESTED THAT FLT ATTENDANTS CHK CABIN TO SEE IF ANYONE WAS OPERATING A PORTABLE ELECTRONIC DEVICE. 1 PAX WAS FOUND TO BE OPERATING A PORTABLE COMPACT DISK PLAYER. FLT ATTENDANTS REQUESTED THAT THE PAX TURN OFF THE CD PLAYER. NO OTHER ANOMALIES WITH THE FO'S HSI OR RMI COMPASS CARDS WERE OBSERVED FOR THE REMAINDER OF THE FLT. GENERAL COMMENTS: NO WARNING FLAGS WERE OBSERVED DURING ANY PORTION OF THE OCCURRENCES. CAPT'S FLT INSTS WERE UNAFFECTED DURING OCCURRENCES. ALL OCCURRENCES OF SUSPECTED ELECTRONIC INTERFERENCE TO FO'S FLT INSTS TOOK PLACE BTWN TOP OF DSCNT AND 10000 FT AGL. NO MAKE ON MODEL OF CD PLAYER COULD BE DETERMINED. UNTIL SUCH TIME THAT CORRECTIVE MEASURES MISTAKEN BY INDUSTRY AND GOV TO RECTIFY POTENTIAL HAZARDS CAUSED BY ELECTRONIC INTERFERENCE; AIRLINE SHOULD GIVE CONSIDERATION TO HAVING PORTABLE ELECTRONIC DEVICES SHUT OFF AT TIME OF DEP. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THE ACFT USED IN THIS INCIDENT WAS AN B737- 200. HE WAS RECOMMENDED TO THE COMPANY TO HAVE A PAX ANNOUNCEMENT EARLY IN THE DSCNT THAT WOULD ASK THAT ALL ELECTRONIC DEVICES BE STORED! HE HAS NOT BEEN GIVEN ANY FEED BACK OF HIS SUGGESTION OR WHAT IF ANYTHING HAS BEEN LEARNED ABOUT OTHER INCIDENTS AND INVESTIGATION OF THIS ONE. HE DOES KNOW THAT THIS INCIDENT WAS TURNED OVER TO THE COMPANY'S AVIONICS SHOP.