Date: 201911
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; First Officer
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Human factors: Situational Awareness
Second reporter function: Flight Attendant (On Duty)
Anomaly: Flight Deck / Cabin / Aircraft Event Illness / Injury; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Attendant; Person Passenger
When detected: In-flight
Result: Flight Crew Overcame Equipment Problem; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: While in cruise; the FA (Flight Attendant)-A called and said that a passenger in first class thought they smelled smoke of some kind; but it was very faint. The flight attendant and other passengers could not smell the fumes at that time. Within about twenty minutes of the first report; a second passenger in first class said they thought they smelled something like what a gas leak in a house would smell like; but again was fairly faint. FA-A had another FA come forward to verify the odor because she could still not detect anything. The other FA said she could not smell anything; either. The first passenger then reported feeling nauseous; having hot flashes; and vomited. Several minutes later; a passenger in row 8 said they smelled a 'dirty socks' smell or something that smelled like sewage. At this time FA-A had the other FA come from the back of the aircraft to verify the smell. This time the aft FA could smell a 'dirty socks' smell. When the Captain and I heard 'dirty socks'; we immediately thought about a fume event and the Captain ran the QRH for Fumes in the cabin. About this time the FA-A reported that her eyes and nose felt like they were getting irritated. After the QRH; procedure was complete and we had turned PACK 1 off; the fumes subsided for the remainder of the flight. The Captain followed the guidance in the FOM and filled out the appropriate reports. The crew debriefed the event after the flight and a Report was submitted. There was some engine work done on the number one engine before we left; apparently replacing a high pressure valve for turbine cooling and additionally adding engine oil to both engines. This may be coincidental but I don't know what other parts the mechanics had to remove to perform this procedure. This was particularly insidious as the smell was quite faint for a long time. Only one passenger smelled it and it seemed to be in conjunction with the ovens at first. The description of the smell was also hard to decipher and only one passenger thought they smelled it for quite a while with no corroboration.


Second narrative: After service passenger in XC informed me she had been smelling an intermittent smoke/gasoline scent throughout the flight. I could not smell anything so I asked the FAs in the back to come and take a look. Neither of them could smell it. I looked for possible issues in the overhead bins and felt the walls but felt nothing strange. I let the passenger know it could've possibly been the oven since it has a strange smell but the pilots did know about the issue and to let me know if she smelled it again. About ten minutes later she rings her call light and smells it- I still did not. Passenger in YA started to get a pain in her stomach and got flashes- she started to vomit. I continued to let the pilots know but there was no guarantee that her illness was because of the smell. At this time we had to break the pilots so the C FA was guarding. After the f/d was closed the C claimed she got a little bit of the smell but she described it as the smell of a gas stove being left on. Not long after; XC claimed she was feeling a little nausea and XA agreed that he had smelled it. I still smelled nothing. C FA started to get a headache and a non rev was using the FC lav so I asked her if she smelled anything during the flight. She claimed she had actually smelled fuel for a moment but it went away during service so she thought nothing of it. XC rings her call light again and claims the smell is very strong so I asked the person in row 6 if he had smelled anything weird. He replied yes actually it smelt like a sewer or a men's locker room. This smell I actually did notice (assuming it was human) and my nose was burning so I let the pilots know. At this time the pilots agreed their nose burned too so they followed their checklist. After they turned off something no one else complained of any smells; YA was not sick anymore and eventually my nose stopped burning. C FA still had her headache. During clean up a passenger in row 7 told me that by the way during the flight she smelt burning. We needed to start precautions when the first complaint was brought to our attention. We should have asked other passengers earlier if they had smelled anything because we could've spent less time in contaminated air.


Synopsis: A320 First Officer reported Flight Attendant and passengers experienced physiological symptoms due to fumes in the cabin.