Narrative:

One hour into flight; at cruise; lead flight attendant called to report a dirty socks smell with a resultant headache. He described the odor localized at row 22; AC left. He further stated that one other flight attendant was feeling dizzy. He went on to say; that flight attendant was well familiar with the odor as he had experienced four previous events. We quickly established sat phone contact with dispatch and maintenance. I advised them that I would keep them informed; especially should the situation worsen. Shortly thereafter; the lead flight attendant called and said the smell was expanding to cover approximately four rows around row 22; now AC left and right. He further stated that more flight attendants were feeling ill with dizziness; coughing and headache symptoms. At this point; I made the decision; with the help of the lead; first officer and [relief pilot] (he had quickly been summoned back to the flight deck from break) to return to ZZZ. I asked the flight attendant to keep me informed. The decision to return to ZZZ was based; in part; that the smell was localized and pax and crew had been moved out of the affected area. Shortly after informing ATC and reversing course; the lead informed me that the majority of crew were now suffering symptoms and that one was vomiting and on O2. At that point; I made the decision to [advise ATC about a medical event] and land as soon as possible which was ZZZ1. At that point we were approximately 60NM north of ZZZ1 at 37;000 feet. Through CRM; duties were assigned; and we began our descent. Because we were so close to ZZZ1; the complete QRH procedure was not completed. Without being too rushed; we got the airplane on the ground approx. 25-30 minutes after the decision to [advise ATC]. A smooth overweight landing (413;000 lbs.) was accomplished with the requisite parameters entered in the logbook. After the pax were removed; our flight attendants and [relief pilot] were taken to the hospital for evaluation.

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Original NASA ASRS Text

Title: A330 flight crew reported executing medical divert due to 'dirty socks' odor in passenger cabin which resulted in the majority of the flight attendants experiencing health issues.

Narrative: One hour into flight; at cruise; lead Flight Attendant called to report a dirty socks smell with a resultant headache. He described the odor localized at row 22; AC left. He further stated that one other Flight Attendant was feeling dizzy. He went on to say; that Flight Attendant was well familiar with the odor as he had experienced four previous events. We quickly established sat phone contact with Dispatch and Maintenance. I advised them that I would keep them informed; especially should the situation worsen. Shortly thereafter; the lead Flight Attendant called and said the smell was expanding to cover approximately four rows around row 22; now AC left and right. He further stated that more flight attendants were feeling ill with dizziness; coughing and headache symptoms. At this point; I made the decision; with the help of the lead; First Officer and [Relief Pilot] (he had quickly been summoned back to the flight deck from break) to return to ZZZ. I asked the Flight Attendant to keep me informed. The decision to return to ZZZ was based; in part; that the smell was localized and pax and crew had been moved out of the affected area. Shortly after informing ATC and reversing course; the Lead informed me that the majority of crew were now suffering symptoms and that one was vomiting and on O2. At that point; I made the decision to [advise ATC about a medical event] and land ASAP which was ZZZ1. At that point we were approximately 60NM north of ZZZ1 at 37;000 feet. Through CRM; duties were assigned; and we began our descent. Because we were so close to ZZZ1; the complete QRH procedure was not completed. Without being too rushed; we got the airplane on the ground approx. 25-30 minutes after the decision to [advise ATC]. A smooth overweight landing (413;000 lbs.) was accomplished with the requisite parameters entered in the logbook. After the pax were removed; our flight attendants and [Relief Pilot] were taken to the hospital for evaluation.

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.