Narrative:

During cruise; FL330; #2 flight attendant calls cockpit to report that a passenger over the left wing is seeing intermittent sparking and a small blue flame in a gap of the wing. The #2 flight attendant confirmed he also saw the same condition. I then called the #1 flight attendant to also look at the wing and confirm what they saw. He also stated that he could see intermittent arcing; like you would see from an electrical short and an intermittent small flame. The first officer then passed back a page from the operations manual with a drawing of the wing. We ask the #1 flight attendant to mark exactly where on the wing they are seeing this. I started evaluating our options on the nearest suitable airport with my first officer and initiated a phone patch with dispatch. I briefed the dispatcher on our situation and she initiated a conference call with maintenance. During this time I had all three flight attendants again look and confirm what they saw on the left wing. Again; all reported intermittent arcing and a small blue flame. I asked my first officer to request a lower altitude in anticipation of diverting. The #1 flight attendant came to the cockpit and showed us on the operations page where on the wing this was happening. The location was on the left wing slat; at the first gap outboard from the fuselage. I passed this information and they suggested we turn off all exterior lights to see if that stopped the problem. We did this; but the flight attendants reported that this did not stop the arcing. At this time we were coming abeam an airport and I asked dispatch if this was a suitable alternate? She confirmed yes and I told her we would be declaring an emergency and diverting into the airport. Contacted center declaring an emergency passed on all required information and requested arff to meet the aircraft on landing; briefed the #1 flight attendant on test items. During descent discussed with my first officer the approach; completed appropriate checklists and briefed after landing intentions; checked in with approach; confirmed emergency aircraft requesting arff after landing. Landed and turned off on taxiway and parked aircraft. Requested arff to inspect left wing for any signs of arcing or burns. They came back negative; so we requested taxi to the gate with arff escort. After completing the parking checklist; my first officer went out to inspect the wing; I briefed the passengers and called dispatch to update them on our situation. First officer returned to report there was no evidence of electrical arcing; burns or fire. I then went outside and met with the station manager; confirming a contract mechanic had been called. We then coordinated with the agents to allow the passengers to deplane and get something to eat or drink. I then met with arff personal and re-inspected the wing/slat area. Again; no indication of arcing or burn marks. Shortly after that I was asked to call the tower. After giving them my cell number; tower called and said they were caught off guard that I wanted arff to respond after landing. I told them we confirmed 'emergency aircraft' and requested arff to meet the aircraft on every frequency we checked in on. Then I received a call from the FAA emergency operation center in washington D.C.; they stated when we used the term 'possible flame' on the wing; it got their attention. I briefly explained the whole situation and that there was no evidence of fire or electrical short. They commended the crew and said to call if we needed any further assistance. When the mechanic arrived; we explained the situation and I called maintenance and dispatch to update them on our status. After conferring on the findings of the crew and mechanic; I said that we felt comfortable continuing with the plane to destination. We re-boarded the passengers; had the logbook signed off and coordinated with dispatch for our flight to continue. Even though there was no evidence of damage; I want to commend the entire crew ontheir performance and professionalism.

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Original NASA ASRS Text

Title: MD83 Captain is informed in cruise that a passenger sees intermittent sparking and a small blue flame on the left wing leading edge slat at the first gap. The flight attendants all concur that they see the same thing and the crew elects to divert to a suitable airport. After landing nothing can be found amiss and the flight eventually continues to destination.

Narrative: During cruise; FL330; #2 Flight Attendant calls cockpit to report that a passenger over the left wing is seeing intermittent sparking and a small blue flame in a gap of the wing. The #2 Flight Attendant confirmed he also saw the same condition. I then called the #1 Flight Attendant to also look at the wing and confirm what they saw. He also stated that he could see intermittent arcing; like you would see from an electrical short and an intermittent small flame. The First Officer then passed back a page from the Operations Manual with a drawing of the wing. We ask the #1 Flight Attendant to mark exactly where on the wing they are seeing this. I started evaluating our options on the nearest suitable airport with my First Officer and initiated a phone patch with Dispatch. I briefed the Dispatcher on our situation and she initiated a conference call with Maintenance. During this time I had all three flight attendants again look and confirm what they saw on the left wing. Again; all reported intermittent arcing and a small blue flame. I asked my First Officer to request a lower altitude in anticipation of diverting. The #1 Flight Attendant came to the cockpit and showed us on the Operations page where on the wing this was happening. The location was on the left wing slat; at the first gap outboard from the fuselage. I passed this information and they suggested we turn off all exterior lights to see if that stopped the problem. We did this; but the flight attendants reported that this did not stop the arcing. At this time we were coming abeam an airport and I asked Dispatch if this was a suitable alternate? She confirmed yes and I told her we would be declaring an emergency and diverting into the airport. Contacted Center declaring an emergency passed on all required information and requested ARFF to meet the aircraft on landing; briefed the #1 Flight Attendant on TEST items. During descent discussed with my First Officer the approach; completed appropriate checklists and briefed after landing intentions; checked in with Approach; confirmed emergency aircraft requesting ARFF after landing. Landed and turned off on taxiway and parked aircraft. Requested ARFF to inspect left wing for any signs of arcing or burns. They came back negative; so we requested taxi to the gate with ARFF escort. After completing the Parking checklist; my First Officer went out to inspect the wing; I briefed the passengers and called Dispatch to update them on our situation. First Officer returned to report there was no evidence of electrical arcing; burns or fire. I then went outside and met with the Station Manager; confirming a Contract Mechanic had been called. We then coordinated with the agents to allow the passengers to deplane and get something to eat or drink. I then met with ARFF personal and re-inspected the wing/slat area. Again; no indication of arcing or burn marks. Shortly after that I was asked to call the Tower. After giving them my cell number; Tower called and said they were caught off guard that I wanted ARFF to respond after landing. I told them we confirmed 'emergency aircraft' and requested ARFF to meet the aircraft on every frequency we checked in on. Then I received a call from the FAA Emergency Operation Center in Washington D.C.; they stated when we used the term 'possible flame' on the wing; it got their attention. I briefly explained the whole situation and that there was no evidence of fire or electrical short. They commended the crew and said to call if we needed any further assistance. When the mechanic arrived; we explained the situation and I called Maintenance and Dispatch to update them on our status. After conferring on the findings of the crew and mechanic; I said that we felt comfortable continuing with the plane to destination. We re-boarded the passengers; had the logbook signed off and coordinated with Dispatch for our flight to continue. Even though there was no evidence of damage; I want to commend the entire crew ontheir performance and professionalism.

Data retrieved from NASA's ASRS site as of April 2012 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.