ACR PIC RPT ON NAVAID INTERFERENCE CREATED BY A PAX OPERATING A HIGH PWRED LAPTOP COMPUTER. PIC HAD SUSPECTED ELECTRONIC MAGNETIC INTERFERENCE AS THE CULPRIT.

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LOCATION: FROM VICINITY FUZ TO S OF PER; WE EXPERIENCED RAW DATA GROSS AND VARIED VOR COURSE INDICATIONS DURING THIS TIME PERIOD. THE PNF (FO) WAS CONTINUOUSLY IN RAW DATA THE ENTIRE FLT AND INITIALLY CALLED TO MY ATTN THE DEVS AND FLUCTUATIONS OF HIS COURSE INDICATOR USING BOTH FUZ AND PER VORTACS. I (PF) WAS USING THE FMC FOR NAV AND EXPERIENCED NO OFF COURSE INDICATIONS NOR CALLS FROM ATC OF A DEV. I CALLED THE #1 FLT ATTENDANT AND HAD HIM DO A COMPUTER COUNT AND TO CHK FOR CELLULAR PHONE USAGE. HE RPTED BACK TO US THAT NO CELL PHONES WERE IN USE AND ONLY 1 LAPTOP IN FIRST CLASS CABIN WAS IN USE. I IMMEDIATELY INSTRUCTED HIM TO ORDER THE COMPUTER TURNED OFF AS WE WATCHED THE NAV DISPLAYS. IMMEDIATELY UPON TURNING OFF THE LAPTOP OUR PRIMARY NAV DISPLAYS INDICATED STEADY NEEDLES AND ON COURSE. THE #1 FLT ATTENDANT RPTED TO ME THAT WHEN HE INFORMED THE PAX TO TURN IT OFF; HE OFFERED NO ARGUMENT AND HE FELT THAT THIS HAD PROBABLY HAPPENED BEFORE. I TRIED TO CATCH PAX DEBOARDING (BUT HE GOT AWAY TOO QUICKLY) SO THAT I COULD EXAMINE THE LAPTOP PERSONALLY. I FEEL THAT HE HAS A SOUPED-UP PWR SOURCE UNUSUAL COMPUTER CONFIGURATION. HE RPTED IT AS A COMPAQ ARMADA 4130T (ALLEGEDLY). WE CHKED THE RAW DATA DISPLAYS VERSUS FMS AND THEY WORKED PERFECTLY ON THE RETURN LEG.