EFIS SCREENS AND AUTONAV FUNCTIONS WERE LOST. PAX ELECTRONIC DEVICE WAS SUSPECTED AS CAUSE.

Narrative

DURING CLB EFIS SCREENS BLANKED SUDDENLY; THEN INDICATED MISSED APCH FAIL ALONG WITH LOSS OF ALL AUTO NAV FUNCTIONS. WE IMMEDIATELY REVERTED TO MANUAL LATERAL NAV AND KEPT THE ACFT CLBING ON AUTOPLT WHILE REQUESTING THE FLT ATTENDANTS TO SEE IF ANY PERSONAL ELECTRONIC DEVICES WERE IN USE. AS THIS ACFT IS EQUIPPED WITH INERTIAL REF UNITS WHICH WERE PROPERLY ALIGNED AT THE GATE IT WAS VERY SUSPICIOUS THAT A FAILURE OCCURRED. THE FLT ATTENDANTS FOUND 3 PAX USING LAPTOP COMPUTERS AND 1 LISTENING TO A PORTABLE RADIO. WE ASKED THAT THEY BE TURNED OFF AND; AFTER REPROGRAMMING THE FMS; RESUMED AUTO NAV. AT CRUISE ALT THE FMS; RESUMED AUTO NAV. AT CRUISE ALT THE LAPTOPS WERE ALLOWED TO BE USED. A SERIOUS STUDY NEEDS TO BE MADE OF THE ELECTRONIC INTERFERENCE PROB ON TODAY'S MODERN FLEETS IN ORDER TO RESOLVE THE ISSUE OF WHAT THE NEWSPAPERS ARE TELLING THE PUBLIC WHAT THEY MAY BRING ABOARD AND USE INFLT. THE PRINTED MATERIAL ON THE ACFT DOES NOT SEEM TO BE EFFECTIVE. WHILE IN THIS EVENT NO SERIOUS HARM WAS DONE; THE EFFECT COULD HAVE BEEN DIFFERENT IF THE ACFT WAS IN HVY WX FLYING A COMPLICATED DEP OR ARR. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR SAID HE WAS FLYING A GLASS COCKPIT ACFT. HE IS NOT SURE WHAT KIND OF DEVICE THE LISTENER WAS USING; A RADIO OR A CD PLAYER BECAUSE THE DEVICE WAS IN A BAG AND ONLY THE HEADSET WAS VISIBLE. AFTER REACHING HIGHER ALT; THE LAPTOP USERS WERE ALLOWED TO RESUME USE OF THEIR COMPUTERS AND THE LISTENER WAS ASKED NOT TO USE HIS DEVICE. THE INTERFERENCE DID NOT RETURN. HE CITED ANOTHER CASE ON A WDB WHERE A LAPTOP WAS ALMOST CERTAINLY THE CAUSE OF THE FLT DIRECTOR COMMAND BARS BEING BIASED OUT OF VIEW.