Narrative:

During climb EFIS screens blanked suddenly, then indicated missed approach fail along with loss of all automatic navigation functions. We immediately reverted to manual lateral navigation and kept the aircraft climbing on autoplt while requesting the flight attendants to see if any personal electronic devices were in use. As this aircraft is equipped with inertial reference units which were properly aligned at the gate it was very suspicious that a failure occurred. The flight attendants found 3 passenger using laptop computers and 1 listening to a portable radio. We asked that they be turned off and, after reprogramming the FMS, resumed automatic navigation. At cruise altitude the FMS, resumed automatic navigation. At cruise altitude the laptops were allowed to be used. A serious study needs to be made of the electronic interference problem 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 in-flight. The printed material on the aircraft does not seem to be effective. While in this event no serious harm was done, the effect could have been different if the aircraft was in heavy WX flying a complicated departure or arrival. Callback conversation with reporter revealed the following information: reporter said he was flying a glass cockpit aircraft. He is not sure what kind of device the listener was using, a radio or a clearance delivery player because the device was in a bag and only the headset was visible. After reaching higher altitude, 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 widebody transport where a laptop was almost certainly the cause of the flight director command bars being biased out of view.

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Original NASA ASRS Text

Title: 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.

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.