Narrative:

Approaching fuzzy intersection while inbound on the fuzzy 3 arrival into las, first officer's flight instruments, 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 heading select mode and altitude hold mode engaged. Just prior to reaching fuzzy intersection, aircraft made an uncommanded 15 degree left turn. Flight crew checked autoplt status to determine if VOR localizer mode was armed, it wasn't. Aircraft began a right turn to original heading when first officer interceded and turned aircraft back to the left to intercept bld VOR 269 degree radial inbound. Descending through approximately 14000 ft, first officer observed that both his HSI and RMI compass cards where slewing plus or minus 70 degrees either side of heading selected (089 degrees). With autoplt still in cmd mode, aircraft made shallow banking motions as it initiated both left and right turns. On next occurrence, first officer engaged cws mode on autoplt to eliminate dutch roll caused by autoplt anomaly. On next occurrence, with autoplt in cws and first officer's HSI and RMI compass cards randomly slewing left and right of heading selected, aircraft remained on desired heading. On next occurrence, it was determined that neither the captain's HSI or RMI compass cards were being affected. Flight crew suspected possible electronic interference. Captain requested that flight attendants check cabin to see if anyone was operating a portable electronic device. 1 passenger was found to be operating a portable compact disk player. Flight attendants requested that the passenger turn off the clearance delivery player. No other anomalies with the first officer's HSI or RMI compass cards were observed for the remainder of the flight. General comments: no warning flags were observed during any portion of the occurrences. Captain's flight instruments were unaffected during occurrences. All occurrences of suspected electronic interference to first officer's flight instruments took place between top of descent and 10000 ft AGL. No make on model of clearance delivery player could be determined. Until such time that corrective measures mistaken by industry and government to rectify potential hazards caused by electronic interference, airline should give consideration to having portable electronic devices shut off at time of departure. Callback conversation with reporter revealed the following information: reporter stated that the aircraft used in this incident was an B737- 200. He was recommended to the company to have a passenger announcement early in the descent 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.

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Original NASA ASRS Text

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

Narrative: 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.

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.