Date: 201906
Location: ZZZZ.Airport, FO
Flight conditions: VMC
Aircraft: B777 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
ATC / advisory: Center ZZZZ
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Human factors: Situational Awareness
Second reporter function: Pilot Flying; Captain
Anomaly: Deviation / Discrepancy - Procedural Hazardous Material Violation; 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: Aircraft Equipment Problem Dissipated; Flight Crew Overcame Equipment Problem; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: At cruise over ZZZ VOR enroute to ZZZZ at FL360 (VMC conditions; smooth ride); when one of the flight attendants called and said that she noticed a strange smell in the forward cabin; and that at the same time a passenger approached her and mentioned the smell also; and complained of a 'heavy feeling' in her chest; causing her to cough. The Flight Attendant asked if we had any indications; which I said we did not; but would look into it. I advised the other First Officer of the conversation; and we began discussing options.While reviewing the flight manual for an appropriate checklist; I received another call from the Flight Attendant stating that some of her colleagues were also having some of the same symptoms; and more passengers were reporting the same. The symptoms were reported as 'heavy feeling' in chest; coughing; and some eye irritation; and a metallic taste. No smoke or haze was reported; and seemed to be from the mid-galley; forward. I informed the Flight Attendant that if it continued to get worse; that we would wake the Captain (as he was about an hour into his break); and that meanwhile; we would continue our efforts to run the appropriate checklist.Again I advised the other First Officer of the conversation (as he had been reviewing the Flight Manual); and discussed whether the SMOKE/FUMES checklist was appropriate or not (we had no flight deck indication of smoke or fumes); and diversion options; if it came to that. It was then that we remembered that we had Dangerous Goods onboard (13 separate items); and reviewed the Dangerous Good summary.Another call from the cabin with yet more of the same report; and it was decided to wake the Captain from his break and inform him of the events. This all happened within a matter of just a few minutes. I called the Captain and informed him of the situation; told him we were about to run the Cabin Air Quality checklist from the Flight Manual; and plans to inform Dispatch. He agreed; and said he would talk to the cabin crew and then join us on the flight deck.We ran the Cabin Air Quality checklist; and had Dispatch call us on the satellite phone; and informed him of the situation. He said he would look into the Dangerous Goods and eventually sent us another set of Dangerous Goods paperwork (which we already had from before departure). About this time; the Captain came to the flight deck; and mentioned that he; too; had noticed the smell while talking to the cabin crew. We had no smell or other indications on the flight deck. Together we reviewed the Dangerous Goods summary and drill codes; one of which mentions possible inhalation and eye irritation.After a few more minutes had passed; we called the Flight Attendant and asked about the air quality. She said it seemed to be improving slightly. We agreed to continue; and the Captain said he would go back and sit in seat 1A for a while and monitor; and then would return to his break. Subsequent checks with the cabin crew seemed to suggest that the problem was being managed. We also informed Dispatch that the issue seemed to be under control. After the Captain and flying First Officer returned from their break; the Captain entered a Maintenance write-up regarding the odor; and that it was possibly (emphasis added) from a leaky Dangerous Goods container.A normal descent; approach; landing and taxi in were accomplished. Upon engine shutdown at the gate; a very strong odor (similar but not exactly like jet exhaust) went through the entire cabin; and for the first time was noticed from the flight deck. When the Gate Agent opened the door; he also commented on the smell. A Tech-Ops representative met us during deplaning and had the Captain fill out a form. At this time; the Flight Attendant asked if we had a list of the Dangerous Goods. We gave her a copy of the Dangerous Goods Summary; as we had already disposed of the entire Dangerous Goods list (and other flight paperwork) in the trash; and it was now spoiled.


Second narrative: I had just taken my break and the First Officers called the bunkroom. They told me that several flight attendants were experiencing dry throat; itching eyes; and headache. I went to the cockpit to help with the situation. We had several packages of hazardous materials in the cargo compartment. The First Officers had already completed the checklist for air quality. The result was to turn off the recirculation fans and improve airflow through the cabin. They had already talked to the Dispatcher about the situation. We decided to monitor the air quality and the flight attendants' reports with regard to their potential respiratory distress. I personally talked to three or four of the flight attendants affected and asked them to keep me advised as to how they were feeling and the smells that they had experienced. I took the rest break seat 1A. I blocked off the cockpit from the cabin with the barrier to keep passengers away from the cockpit in the event that I had to return to the cockpit rapidly. About 45 minutes to an hour later the Chief Purser came to me and said the air quality was getting better and the affected flight attendants were feeling better. There were also two passengers who felt the effects of the air quality or lack thereof. Two hours after the incident everyone was feeling much better so we decided that the recirculation fans in the off position had a positive effect. We continued the flight to ZZZZ.We had reviewed all of the checklists associated with smoke fire fumes and diversion in the event that we had to go somewhere immediately or put the cockpit on 100% oxygen. We also made a maintenance write-up and sent that via ACARS. We also sent a note to the station in ZZZZ. We asked them to inspect the hazardous material shipments to make sure they were intact and secure after landing. Maintenance personnel met the flight and asked us to fill out a report on smoke or fumes. We debriefed the situation and felt like we had covered all of the necessary checklists and that the air quality did improve so there was no need to [advise ATC] or divert.


Synopsis: B777 flight crew reported Flight Attendant notification of 'strange fumes' in cabin noticed by cabin crew and passengers. Cabin crew also reported experiencing health issues. Flight crew completed appropriate checklist as the fumes dissipated until gate arrival at destination.