Narrative:

Our flight went to the deice pad. Both engines were kept running while the aircraft was deiced. The airplane was treated initially with type 'I' and later with type 'iv' 100% kilfrost. All winter operations procedures were followed after the deicing and a max power takeoff was performed. Approximately; 15 minutes after takeoff; flight attendant 1; calls the cockpit and tells us the lavatory smoke detector in the aft cabin forward lavatory is going off. According to the flight attendants. The lavatory area was immediately inspected for any evidence of smoke/fire. No evidence was found and the smoke detector reset. A few minutes later the smoke detector starts to sound once again. The flight attendants called the cockpit again. Flight attendant 2 tells us that the detector is going off and he is noticing a haze inside the aft cabin area. At this time the odor of deicing fluid is prevalent inside the cockpit. The purser; (flight attendant 3); has been on the interphone keeping us updated and says she can also see the haze in the cabin. I asked flight attendant 2 if the odor he smelled was deicing fluid. He said he thought it was. I told the flight attendants to continue to monitor the cabin condition and to report to me any changes to the situation. We were climbing to FL290 at the time and I began to look into possible diversion airports. First officer and I suspect that this is all due to deicing fluid being ducted through the bleed system and into the cabin. We turn the right hand recirc fan 'off' so the pacts would operate in high flow in order to move more cabin air and vent the odor. The purser calls and says that the smoke detector at the mid cabin lavatory by door 2L is now going off. I asked if the haze was getting worse or better. Flight attendant 2 called from aft cabin and said that the haze seemed to be dissipating. The purser said she had to keep resetting the smoke detector in the mid lavatory. For a few minutes we continued to get ready for a possible diversion and emergency while investigating the source. According to the flight attendants; passengers were showing signs of concern. About this time the haze continued to dissipate and both the purser and flight attendant 2 confirmed that the cabin air was getting clearer. First officer made a PA announcement to the passenger and reassured them that we were investigating the source for the lavatory smoke detectors going off; although we suspected it was due to the residual deicing fluid. The cabin air cleared and the lavatory smoke detectors stopped going off. We continued to destination for an uneventful landing. I believe some research into the procedures for deicing and the amount of deicing fluid that might be ingested through the engine core or accumulated into the bleed system might be in order.

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Original NASA ASRS Text

Title: B757 Captain is informed of lavatory smoke alarms going off 15 minutes after departure by Cabin Attendants. No smoke is apparent but aircraft had been deiced prior to takeoff and deice fluid is suspected as the cause. Steps are taken to increase air flow and the smoke alarms stop sounding.

Narrative: Our flight went to the Deice Pad. Both engines were kept running while the aircraft was deiced. The airplane was treated initially with type 'I' and later with type 'IV' 100% Kilfrost. All winter operations procedures were followed after the deicing and a max power takeoff was performed. Approximately; 15 minutes after takeoff; Flight Attendant 1; calls the cockpit and tells us the lavatory smoke detector in the aft cabin forward lavatory is going off. According to the flight attendants. The lavatory area was immediately inspected for any evidence of smoke/fire. No evidence was found and the smoke detector reset. A few minutes later the smoke detector starts to sound once again. The flight attendants called the cockpit again. Flight Attendant 2 tells us that the detector is going off and he is noticing a haze inside the aft cabin area. At this time the odor of deicing fluid is prevalent inside the cockpit. The Purser; (Flight Attendant 3); has been on the interphone keeping us updated and says she can also see the haze in the cabin. I asked Flight Attendant 2 if the odor he smelled was deicing fluid. He said he thought it was. I told the flight attendants to continue to monitor the cabin condition and to report to me any changes to the situation. We were climbing to FL290 at the time and I began to look into possible diversion airports. First Officer and I suspect that this is all due to deicing fluid being ducted through the bleed system and into the cabin. We turn the right hand RECIRC FAN 'off' so the pacts would operate in high flow in order to move more cabin air and vent the odor. The Purser calls and says that the smoke detector at the mid cabin lavatory by door 2L is now going off. I asked if the haze was getting worse or better. Flight Attendant 2 called from aft cabin and said that the haze seemed to be dissipating. The Purser said she had to keep resetting the smoke detector in the mid lavatory. For a few minutes we continued to get ready for a possible diversion and emergency while investigating the source. According to the flight attendants; passengers were showing signs of concern. About this time the haze continued to dissipate and both The Purser and Flight Attendant 2 confirmed that the cabin air was getting clearer. First Officer made a PA announcement to the passenger and reassured them that we were investigating the source for the lavatory smoke detectors going off; although we suspected it was due to the residual deicing fluid. The cabin air cleared and the lavatory smoke detectors stopped going off. We continued to destination for an uneventful landing. I believe some research into the procedures for deicing and the amount of deicing fluid that might be ingested through the engine core or accumulated into the bleed system might be in order.

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.