Narrative:

At gate; when crew (3 pilots; 11 flight attendants) boarded aircraft; emergency exit lights inside aircraft started flashing intermittently. Master emergency exit lights switch in cockpit was off. Could not turn off flashing emergency exit lights. Mechanics could not find cause. Crew switched to another aircraft. Same phenomenon occurred on second aircraft when crew boarded. Seemed to indicate that crew triggered the activation of the emergency exit lights. Crew exited aircraft with all crew bags onto the jetbridge. Security personnel examined each crew member bag to check if an electronic device inside a bag triggered the emergency exit lights system. No such device was discovered. Flight crew individually reentered the aircraft in delayed sequence to check each crew member. 1 crew member was entering the aircraft when emergency light flashed briefly. Baggage was checked again; but nothing was found and lights did not flash again. No further system malfunction and aircraft departed for destination. After 2 hours into flight at cruise; emergency exit lights flashed intermittently briefly for approximately 10 seconds. No further flashing occurred for remainder of flight. Logbook entry made at destination.

Related reports:

Google
 

Original NASA ASRS Text

Title: A B777 EMER EXIT LIGHTS WERE FLICKERING. THE FLT CREW CHANGED ACFT AND THE EMER EXITS LIGHT FLASHED ON THE NEW ACFT ALSO.

Narrative: AT GATE; WHEN CREW (3 PLTS; 11 FLT ATTENDANTS) BOARDED ACFT; EMER EXIT LIGHTS INSIDE ACFT STARTED FLASHING INTERMITTENTLY. MASTER EMER EXIT LIGHTS SWITCH IN COCKPIT WAS OFF. COULD NOT TURN OFF FLASHING EMER EXIT LIGHTS. MECHS COULD NOT FIND CAUSE. CREW SWITCHED TO ANOTHER ACFT. SAME PHENOMENON OCCURRED ON SECOND ACFT WHEN CREW BOARDED. SEEMED TO INDICATE THAT CREW TRIGGERED THE ACTIVATION OF THE EMER EXIT LIGHTS. CREW EXITED ACFT WITH ALL CREW BAGS ONTO THE JETBRIDGE. SECURITY PERSONNEL EXAMINED EACH CREW MEMBER BAG TO CHK IF AN ELECTRONIC DEVICE INSIDE A BAG TRIGGERED THE EMER EXIT LIGHTS SYS. NO SUCH DEVICE WAS DISCOVERED. FLT CREW INDIVIDUALLY REENTERED THE ACFT IN DELAYED SEQUENCE TO CHK EACH CREW MEMBER. 1 CREW MEMBER WAS ENTERING THE ACFT WHEN EMER LIGHT FLASHED BRIEFLY. BAGGAGE WAS CHKED AGAIN; BUT NOTHING WAS FOUND AND LIGHTS DID NOT FLASH AGAIN. NO FURTHER SYS MALFUNCTION AND ACFT DEPARTED FOR DEST. AFTER 2 HRS INTO FLT AT CRUISE; EMER EXIT LIGHTS FLASHED INTERMITTENTLY BRIEFLY FOR APPROX 10 SECONDS. NO FURTHER FLASHING OCCURRED FOR REMAINDER OF FLT. LOGBOOK ENTRY MADE AT DEST.

Data retrieved from NASA's ASRS site as of January 2009 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.