Narrative:

I was the captain with 2 first officer's. During flight at takeoff and 1:30 a flight attendant called to report a smell/fume of melting plastic. Shortly after the call the first officer on break called to come into the cockpit to report a vibration in business class with the same melting plastic smell. Just prior to all of this the first officer who was acting as PF and myself noted a loud humming noise in the radome area but no smell or fumes. I directed the flight attendants to check the galley areas and ovens for any possible sources for the smell. The origin of the smell was indiscernible and within a few mins had dissipated with no other indications. The noise and vibration remained with no other indications of anything abnormal. The other pilots and I discussed any possible differences between the B757 versus B767 normal noises and couldn't arrive at a consensus of any aircraft differences that could be the cause. With no smell remaining and the vibration becoming virtually negligible and no other indications of an abnormality I asked the other pilots and the flight attendants if they had any concerns with the continuation of the flight with the flight attendants read on the passenger and the consensus was to proceed. This decision occurred approximately takeoff and 2:00. At takeoff and 2:30 a more pronounced noise with vibration occurred in the radome area with an inoperative light illuminating in the left recirc fan accompanied with the associated EICAS message. The first officer and I referenced and accomplished the QRH procedure for the left recirc fan inoperative light EICAS which required no action by the crew information only. Almost simultaneously with the completion of the QRH procedure the flight attendants called to report the smell had returned and stated the smell was much worse than before and that it had more of an acrid; electrical smell which was then followed with a haze forming in the aft cabin and it is moving forward. At this point the first officer and I donned our oxygen masks and established communications in the cockpit. I directed him to fly and handle the ATC communications. The relief first officer called and stated the vibration was apparent in business class again only worse than before. I asked her to return to the cockpit to assist in the situation. At this time we requested radar vectors to turn away from nat. The first officer as PF continued while the relief first officer and I accomplished the smoke or fire or fumes checklist in the QRH while simultaneously coordinating with the dispatcher via ACARS for a divert to the nearest suitable airfield for the situation we were in. From the geographic position we were at; ZZZZ was the nearest suitable airfield with the situation at that point worsening with the haze increasing as reported by the flight attendant in the aft cabin. As we were accomplishing the QRH procedure for smoke or fire or fumes and in the descent; the flight attendant additionally reported a worsening of the smell in the cabin. Only after the QRH step to turn off the left recirculation fan switch did the flight attendant report that it seemed to be improving but was still present. I had the first officer continue as the PF while the relief first officer and I completed the QRH to the point that the flight attendant said the haze was starting to lessen and the smell was diminishing. At approximately 18000 ft the smell was no longer evident in the cockpit and we all removed the oxygen masks. We declared an emergency and continued the descent and landing with accomplishment of all normal checklists. After consulting the QRH; I elected to not dump fuel so that we could land as soon as possible. I had the first officer accomplish the descent; approach and landing via a visual approach to runway xx. Reference to the aircraft's landing distance chart indicated a landing distance of 5400 ft. We conducted the visual approach to runway xx with the back course/localizer as a back up as the longer runway was closed. I conducted the pm duties and continued to monitor the situation in the cabin with the relief first officer and the lead flight attendant as well as coordinate with the tower and emergency personnel for the post landing inspection. Landing was uneventful. Afterward; first officer noted that it was difficult to communicate while wearing the oxygen mask. There is only listening capability at this jumpseat; with no place to plug in the microphone cord. This means the relief pilot has no way to communicate with other pilots; flight attendants; or outside agencies without removing the oxygen mask first and from the other jumpseat it is difficult to see the panels or out the windows; and nearly impossible to reach the interphone handset.

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Original NASA ASRS Text

Title: B767 CAPT REPORTS PLASTIC FUMES AND FAINT VIBRATION 90 MINUTES INTO FLIGHT. AT 2:30 INTO FLT VIBRATION RETURNS AND RECIRC FAN INOP LIGHT ILLUMINATES. FUMES RETURN MUCH STRONGER AND FLIGHT DIVERTS.

Narrative: I WAS THE CAPT WITH 2 FO'S. DURING FLT AT TKOF AND 1:30 A FLT ATTENDANT CALLED TO RPT A SMELL/FUME OF MELTING PLASTIC. SHORTLY AFTER THE CALL THE FO ON BREAK CALLED TO COME INTO THE COCKPIT TO RPT A VIBRATION IN BUSINESS CLASS WITH THE SAME MELTING PLASTIC SMELL. JUST PRIOR TO ALL OF THIS THE FO WHO WAS ACTING AS PF AND MYSELF NOTED A LOUD HUMMING NOISE IN THE RADOME AREA BUT NO SMELL OR FUMES. I DIRECTED THE FLT ATTENDANTS TO CHK THE GALLEY AREAS AND OVENS FOR ANY POSSIBLE SOURCES FOR THE SMELL. THE ORIGIN OF THE SMELL WAS INDISCERNIBLE AND WITHIN A FEW MINS HAD DISSIPATED WITH NO OTHER INDICATIONS. THE NOISE AND VIBRATION REMAINED WITH NO OTHER INDICATIONS OF ANYTHING ABNORMAL. THE OTHER PLTS AND I DISCUSSED ANY POSSIBLE DIFFERENCES BTWN THE B757 VERSUS B767 NORMAL NOISES AND COULDN'T ARRIVE AT A CONSENSUS OF ANY ACFT DIFFERENCES THAT COULD BE THE CAUSE. WITH NO SMELL REMAINING AND THE VIBRATION BECOMING VIRTUALLY NEGLIGIBLE AND NO OTHER INDICATIONS OF AN ABNORMALITY I ASKED THE OTHER PLTS AND THE FLT ATTENDANTS IF THEY HAD ANY CONCERNS WITH THE CONTINUATION OF THE FLT WITH THE FLT ATTENDANTS READ ON THE PAX AND THE CONSENSUS WAS TO PROCEED. THIS DECISION OCCURRED APPROX TKOF AND 2:00. AT TKOF AND 2:30 A MORE PRONOUNCED NOISE WITH VIBRATION OCCURRED IN THE RADOME AREA WITH AN INOP LIGHT ILLUMINATING IN THE L RECIRC FAN ACCOMPANIED WITH THE ASSOCIATED EICAS MESSAGE. THE FO AND I REFED AND ACCOMPLISHED THE QRH PROC FOR THE L RECIRC FAN INOP LIGHT EICAS WHICH REQUIRED NO ACTION BY THE CREW INFO ONLY. ALMOST SIMULTANEOUSLY WITH THE COMPLETION OF THE QRH PROC THE FLT ATTENDANTS CALLED TO RPT THE SMELL HAD RETURNED AND STATED THE SMELL WAS MUCH WORSE THAN BEFORE AND THAT IT HAD MORE OF AN ACRID; ELECTRICAL SMELL WHICH WAS THEN FOLLOWED WITH A HAZE FORMING IN THE AFT CABIN AND IT IS MOVING FORWARD. AT THIS POINT THE FO AND I DONNED OUR OXYGEN MASKS AND ESTABLISHED COMS IN THE COCKPIT. I DIRECTED HIM TO FLY AND HANDLE THE ATC COMS. THE RELIEF FO CALLED AND STATED THE VIBRATION WAS APPARENT IN BUSINESS CLASS AGAIN ONLY WORSE THAN BEFORE. I ASKED HER TO RETURN TO THE COCKPIT TO ASSIST IN THE SITUATION. AT THIS TIME WE REQUESTED RADAR VECTORS TO TURN AWAY FROM NAT. THE FO AS PF CONTINUED WHILE THE RELIEF FO AND I ACCOMPLISHED THE SMOKE OR FIRE OR FUMES CHKLIST IN THE QRH WHILE SIMULTANEOUSLY COORDINATING WITH THE DISPATCHER VIA ACARS FOR A DIVERT TO THE NEAREST SUITABLE AIRFIELD FOR THE SITUATION WE WERE IN. FROM THE GEOGRAPHIC POS WE WERE AT; ZZZZ WAS THE NEAREST SUITABLE AIRFIELD WITH THE SITUATION AT THAT POINT WORSENING WITH THE HAZE INCREASING AS RPTED BY THE FLT ATTENDANT IN THE AFT CABIN. AS WE WERE ACCOMPLISHING THE QRH PROC FOR SMOKE OR FIRE OR FUMES AND IN THE DSCNT; THE FLT ATTENDANT ADDITIONALLY RPTED A WORSENING OF THE SMELL IN THE CABIN. ONLY AFTER THE QRH STEP TO TURN OFF THE L RECIRCULATION FAN SWITCH DID THE FLT ATTENDANT RPT THAT IT SEEMED TO BE IMPROVING BUT WAS STILL PRESENT. I HAD THE FO CONTINUE AS THE PF WHILE THE RELIEF FO AND I COMPLETED THE QRH TO THE POINT THAT THE FLT ATTENDANT SAID THE HAZE WAS STARTING TO LESSEN AND THE SMELL WAS DIMINISHING. AT APPROX 18000 FT THE SMELL WAS NO LONGER EVIDENT IN THE COCKPIT AND WE ALL REMOVED THE OXYGEN MASKS. WE DECLARED AN EMER AND CONTINUED THE DSCNT AND LNDG WITH ACCOMPLISHMENT OF ALL NORMAL CHKLISTS. AFTER CONSULTING THE QRH; I ELECTED TO NOT DUMP FUEL SO THAT WE COULD LAND AS SOON AS POSSIBLE. I HAD THE FO ACCOMPLISH THE DSCNT; APCH AND LNDG VIA A VISUAL APCH TO RWY XX. REF TO THE ACFT'S LNDG DISTANCE CHART INDICATED A LNDG DISTANCE OF 5400 FT. WE CONDUCTED THE VISUAL APCH TO RWY XX WITH THE BC/LOC AS A BACK UP AS THE LONGER RWY WAS CLOSED. I CONDUCTED THE PM DUTIES AND CONTINUED TO MONITOR THE SITUATION IN THE CABIN WITH THE RELIEF FO AND THE LEAD FLT ATTENDANT AS WELL AS COORDINATE WITH THE TWR AND EMER PERSONNEL FOR THE POST LNDG INSPECTION. LNDG WAS UNEVENTFUL. AFTERWARD; FO NOTED THAT IT WAS DIFFICULT TO COMMUNICATE WHILE WEARING THE OXYGEN MASK. THERE IS ONLY LISTENING CAPABILITY AT THIS JUMPSEAT; WITH NO PLACE TO PLUG IN THE MIKE CORD. THIS MEANS THE RELIEF PLT HAS NO WAY TO COMMUNICATE WITH OTHER PLTS; FLT ATTENDANTS; OR OUTSIDE AGENCIES WITHOUT REMOVING THE OXYGEN MASK FIRST AND FROM THE OTHER JUMPSEAT IT IS DIFFICULT TO SEE THE PANELS OR OUT THE WINDOWS; AND NEARLY IMPOSSIBLE TO REACH THE INTERPHONE HANDSET.

Data retrieved from NASA's ASRS site as of May 2009 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.