Narrative:

Aircraft at cruise FL390 (captain PF). Approximately 40 mins after takeoff; a mid cabin lavatory smoke detector activated. Flight attendant advised pilots of the detector and a full inspection of lavatory and waste basket with no findings of smoke; fire or other suspicious debris. Flight attendant determined a faulty detector. The lavatory was locked out with detector being disarmed. Approximately 15 mins later; flight attendant reported multiple lavatory smoke detectors (3) activated; along with a faint burning smell. Flight attendant also reported a 'haze' beginning to accumulate in the cabin. An emergency was declared with ATC and the abnormal (QRH) checklist was initiated. The captain remained in control of the aircraft and with ATC and the first officer ran the QRH checklist as well as communications with the flight attendants. Initial descent to FL250 with subsequent clearance to 10000 ft. A brief PA was made by first officer to passenger informing them of situation. ZZZ was selected as divert airport. During descent and before QRH checklist was completed; maintenance sent an ACARS message suggestion to shut off left pack. Shortly after pack was turned off; flight attendant reported haze and smell subsided. Once with approach control; emergency equipment was requested on approach. Flight attendant reported haze and smell was gone. After normal landing; aircraft was brought to a stop on taxiway and an exterior inspection was done by fire squad. After completion of exterior inspection; aircraft was taxied to the ramp and shut down. Passenger deplaned utilizing air stairs in an orderly fashion. Aircraft interior and cargo holds were inspected by fire crew with no evidence of fire found.

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Original NASA ASRS Text

Title: A B767-300 IN CRUISE AT FL390 DECLARED AN EMER AND DIVERTED DUE TO LAVATORY SMOKE DETECTORS ACTIVATED AND HAZE IN CABIN AIR.

Narrative: ACFT AT CRUISE FL390 (CAPT PF). APPROX 40 MINS AFTER TKOF; A MID CABIN LAVATORY SMOKE DETECTOR ACTIVATED. FLT ATTENDANT ADVISED PLTS OF THE DETECTOR AND A FULL INSPECTION OF LAVATORY AND WASTE BASKET WITH NO FINDINGS OF SMOKE; FIRE OR OTHER SUSPICIOUS DEBRIS. FLT ATTENDANT DETERMINED A FAULTY DETECTOR. THE LAVATORY WAS LOCKED OUT WITH DETECTOR BEING DISARMED. APPROX 15 MINS LATER; FLT ATTENDANT RPTED MULTIPLE LAVATORY SMOKE DETECTORS (3) ACTIVATED; ALONG WITH A FAINT BURNING SMELL. FLT ATTENDANT ALSO RPTED A 'HAZE' BEGINNING TO ACCUMULATE IN THE CABIN. AN EMER WAS DECLARED WITH ATC AND THE ABNORMAL (QRH) CHKLIST WAS INITIATED. THE CAPT REMAINED IN CTL OF THE ACFT AND WITH ATC AND THE FO RAN THE QRH CHKLIST AS WELL AS COMS WITH THE FLT ATTENDANTS. INITIAL DSCNT TO FL250 WITH SUBSEQUENT CLRNC TO 10000 FT. A BRIEF PA WAS MADE BY FO TO PAX INFORMING THEM OF SITUATION. ZZZ WAS SELECTED AS DIVERT ARPT. DURING DSCNT AND BEFORE QRH CHKLIST WAS COMPLETED; MAINT SENT AN ACARS MESSAGE SUGGESTION TO SHUT OFF L PACK. SHORTLY AFTER PACK WAS TURNED OFF; FLT ATTENDANT RPTED HAZE AND SMELL SUBSIDED. ONCE WITH APCH CTL; EMER EQUIP WAS REQUESTED ON APCH. FLT ATTENDANT RPTED HAZE AND SMELL WAS GONE. AFTER NORMAL LNDG; ACFT WAS BROUGHT TO A STOP ON TXWY AND AN EXTERIOR INSPECTION WAS DONE BY FIRE SQUAD. AFTER COMPLETION OF EXTERIOR INSPECTION; ACFT WAS TAXIED TO THE RAMP AND SHUT DOWN. PAX DEPLANED UTILIZING AIR STAIRS IN AN ORDERLY FASHION. ACFT INTERIOR AND CARGO HOLDS WERE INSPECTED BY FIRE CREW WITH NO EVIDENCE OF FIRE FOUND.

Data retrieved from NASA's ASRS site as of January 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.