Narrative:

Climbing to FL370; about 50 minutes into flight; the first officer and I noticed a hot; electrical smell. We queried the flight attendants and they also smelled it. No smoke was visible and none reported. We had the engine anti-ice on and saw a lot of st. Elmo's fire on our windscreens. The relief pilot (international relief officer) came forward from the crew-rest seat as he also noticed the smell. The flight attendants and international relief officer walked through the cabin to try to localize the source; especially the galleys; with no results. The first officer and I were on oxygen as a precaution. We leveled off clear of clouds and static and turned off the engine anti-ice. The smell seemed to dissipate some. The flight attendants reported passengers expressing concern with some complaining of minor eye irritation. As pilot monitoring; I contacted dispatch and maintenance control. Maintenance suggested some steps to localize the source when the lead flight attendant reported that the one flight attendant was feeling poorly and going on oxygen. I then told dispatch we were diverting and they requested we return to the departure airport. I did not consider that it was necessary to divert to the nearest airport as there was no smoke and the smell seemed to be diminishing. We turned toward the departure airport and in the descent through clouds; the smell seemed to increase again so we declared an emergency with ATC to receive priority handling and high speed descent. The smell again seemed to decrease. I assumed pilot flying duties and made a normal landing in VFR weather. As requested; paramedics met us at the gate. We asked passengers to remain seated so those wanting assistance (3 flight attendants and 2 passengers) could be seen to. Four flight attendants went with the paramedics for tests/observation. I filled out the odor report form; made a lengthy entry in the fdml and spoke to a maintenance supervisor. The first officer; international relief officer and I felt no ill effects other than possible mild eye irritation. Electrical smell from unknown source.

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Original NASA ASRS Text

Title: An A330 in heavy St Elmo's fire with engine anti-ice on developed a strong electrical odor which crew and passengers reacted to; so the flight returned to the departure airport. Maintenance discovered no anomalies and suspected a weather related phenomenon.

Narrative: Climbing to FL370; about 50 minutes into flight; the First Officer and I noticed a hot; electrical smell. We queried the flight attendants and they also smelled it. No smoke was visible and none reported. We had the engine anti-ice on and saw a lot of St. Elmo's fire on our windscreens. The Relief Pilot (IRO) came forward from the crew-rest seat as he also noticed the smell. The flight attendants and IRO walked through the cabin to try to localize the source; especially the galleys; with no results. The First Officer and I were on oxygen as a precaution. We leveled off clear of clouds and static and turned off the engine anti-ice. The smell seemed to dissipate some. The flight attendants reported passengers expressing concern with some complaining of minor eye irritation. As pilot monitoring; I contacted Dispatch and Maintenance Control. Maintenance suggested some steps to localize the source when the Lead Flight Attendant reported that the one Flight Attendant was feeling poorly and going on oxygen. I then told Dispatch we were diverting and they requested we return to the departure airport. I did not consider that it was necessary to divert to the nearest airport as there was no smoke and the smell seemed to be diminishing. We turned toward the departure airport and in the descent through clouds; the smell seemed to increase again so we declared an emergency with ATC to receive priority handling and high speed descent. The smell again seemed to decrease. I assumed pilot flying duties and made a normal landing in VFR weather. As requested; paramedics met us at the gate. We asked passengers to remain seated so those wanting assistance (3 flight attendants and 2 passengers) could be seen to. Four flight attendants went with the paramedics for tests/observation. I filled out the odor report form; made a lengthy entry in the FDML and spoke to a Maintenance Supervisor. The First Officer; IRO and I felt no ill effects other than possible mild eye irritation. Electrical smell from unknown source.

Data retrieved from NASA's ASRS site 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.