Narrative:

Flight departed and climbed to cruise altitude without incident. Shortly after reaching cruise altitude; an aft flight attendant called stating that the aft-fwd lavatory smoke alarm was going off. A passenger emerged from the lavatory shortly after the alarm was heard. Flight attendant reported that the detector had not been tampered with; nor had the passenger smoked a cigarette. The detector was reset by the flight attendant. Several moments later a different passenger used the same lavatory and the smoke detector again sounded. This was relayed to the cockpit and the flight attendant was instructed to again reset the detector. A few minutes later a call from a forward flight attendant; relayed that she could see smoke or a haze in the aft cabin. A very faint acrid odor was detected in the cockpit. The smoke/fire/fumes QRH was begun and the possibility of a diversion was discussed. The aft flight attendant could not locate a fire source. After the QRH; the smoke in the aft cabin appeared to have gotten thicker according to a forward positioned flight attendant. An emergency was declared and we decided to divert to the nearest suitable airport. An approach briefing and discussion with ATC on runway availability ensued. A cabin advisory was issued to the flight attendant's. A normal landing and runway exit was accomplished. Fire trucks and the control tower detected no exterior smoke or flames. Shortly after touchdown cabin air cleared. Aircraft was shutdown normally and passengers were deplaned via stairs.

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Original NASA ASRS Text

Title: B757-200 flight crew reported they were informed lavatory smoke alarms had activated for no apparent reason. After resetting the alarms twice; a faint haze was detected in in the cabin and the flight crew elects to divert to the nearest suitable airport.

Narrative: Flight departed and climbed to cruise altitude without incident. Shortly after reaching cruise altitude; an aft Flight Attendant called stating that the aft-fwd lavatory smoke alarm was going off. A passenger emerged from the lavatory shortly after the alarm was heard. Flight Attendant reported that the detector had not been tampered with; nor had the passenger smoked a cigarette. The detector was reset by the Flight Attendant. Several moments later a different passenger used the same lavatory and the smoke detector again sounded. This was relayed to the cockpit and the Flight Attendant was instructed to again reset the detector. A few minutes later a call from a forward Flight Attendant; relayed that she could see smoke or a haze in the aft cabin. A very faint acrid odor was detected in the cockpit. The Smoke/Fire/Fumes QRH was begun and the possibility of a diversion was discussed. The aft Flight Attendant could not locate a fire source. After the QRH; the smoke in the aft cabin appeared to have gotten thicker according to a forward positioned Flight Attendant. An emergency was declared and we decided to divert to the nearest suitable airport. An approach briefing and discussion with ATC on runway availability ensued. A cabin advisory was issued to the Flight Attendant's. A normal landing and runway exit was accomplished. Fire trucks and the Control Tower detected no exterior smoke or flames. Shortly after touchdown cabin air cleared. Aircraft was shutdown normally and passengers were deplaned via stairs.

Data retrieved from NASA's ASRS site as of April 2012 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.