Narrative:

After leveling off last night on our way back; we experienced a couple of incidents of saint elmo's fire on both forward windscreens. Although it was only visible a few times we could both hear the sound of it sporadically though it was no longer visible. We began our initial descent on the arrival early because of continuous light chop due to associated weather in the area. After setting the assigned altitude; I attempted to go into vertical speed mode on the MCP; however; the window did not illuminate when I thumbed the wheel to start our descent. I then selected level change to no avail and then VNAV. I initiated the descent in cws pitch mode. At that point it dawned on us that the clicking sound we were hearing may be arcing and not saint elmo's fire since the MCP was unresponsive. We both began looking around and that's when I noticed there was some electrical arcing on the inside of my forward windscreen just to the left of the fold down handle. At that point; I pointed it out to the captain and he verified it as well. He let the flight attendants know that we were experiencing the arcing and to let him know if they had any abnormal indications in the cabin. The captain also notified center and I believe they cleared us directly to destination. A few minutes later the a flight attendant called us and said that there was smoke in the forward part of the cabin/galley. We both donned our oxygen mask and I put my goggles on and also retrieved the cockpit fire extinguisher so that it was readily available. The captain asked ATC what the nearest airport was and we turned towards it. Descending; the arcing would intensify and then dissipate. During the descent; the only functions of the MCP that would work were the heading knob and the course selector for the HSI although the autopilot would not couple to any vertical or lateral modes. The IAS window was stuck so the speed bug could only be selected manually. We landed uneventfully and taxied into the gate with no further incidents.communications became a barrier once we put our oxygen masks on because the captain could not hear me or ATC through his headset and so he had his speaker on. This caused us to get a lot of feedback making communications even more difficult. He took control of the aircraft as well as the comms. I continued through the smoke in the cockpit checklist since we were having problems communicating with each other on the flight intercom. We tried to troubleshoot this on the ground and also in the follow on aircraft (the captains headset worked fine with the mask on). I don't know if this is a just an isolated problem or if it's an equipment issue. I was wearing a bose X headset and the captain was wearing a telex 850 headset.

Related reports:

Google
 

Original NASA ASRS Text

Title: B737 First Officer reports MCP failure during descent with arcing along the bottom of the windshield. Smoke is reported in the forward part of the cabin and the crew elects to divert and experiences intra cockpit communication difficulties using oxygen masks and smoke goggles.

Narrative: After leveling off last night on our way back; we experienced a couple of incidents of Saint Elmo's fire on both forward windscreens. Although it was only visible a few times we could both hear the sound of it sporadically though it was no longer visible. We began our initial descent on the arrival early because of continuous light chop due to associated weather in the area. After setting the assigned altitude; I attempted to go into Vertical Speed mode on the MCP; however; the window did not illuminate when I thumbed the wheel to start our descent. I then selected Level Change to no avail and then VNAV. I initiated the descent in CWS Pitch mode. At that point it dawned on us that the clicking sound we were hearing may be arcing and not Saint Elmo's fire since the MCP was unresponsive. We both began looking around and that's when I noticed there was some electrical arcing on the inside of my forward windscreen just to the left of the fold down handle. At that point; I pointed it out to the Captain and he verified it as well. He let the Flight Attendants know that we were experiencing the arcing and to let him know if they had any abnormal indications in the cabin. The Captain also notified Center and I believe they cleared us directly to destination. A few minutes later the A Flight Attendant called us and said that there was smoke in the forward part of the cabin/galley. We both donned our oxygen mask and I put my goggles on and also retrieved the cockpit fire extinguisher so that it was readily available. The Captain asked ATC what the nearest airport was and we turned towards it. Descending; the arcing would intensify and then dissipate. During the descent; the only functions of the MCP that would work were the heading knob and the course selector for the HSI although the autopilot would not couple to any vertical or lateral modes. The IAS window was stuck so the speed bug could only be selected manually. We landed uneventfully and taxied into the gate with no further incidents.Communications became a barrier once we put our oxygen masks on because the Captain could not hear me or ATC through his headset and so he had his speaker on. This caused us to get a lot of feedback making communications even more difficult. He took control of the aircraft as well as the comms. I continued through the Smoke in the Cockpit Checklist since we were having problems communicating with each other on the flight intercom. We tried to troubleshoot this on the ground and also in the follow on aircraft (The Captains headset worked fine with the mask on). I don't know if this is a just an isolated problem or if it's an equipment issue. I was wearing a Bose X Headset and the Captain was wearing a Telex 850 headset.

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.