MD80 flight crew was informed by the flight attendants that two lavatory smoke alarms are going off ...

Narrative:

Shortly after gear was retracted during a normal takeoff the flight attendants chimed us stating the lavatory fire detection system in the aft lavatory was alarming. Seconds later a second alarm began to ring; but this time in the forward lavatory. The flight attendants quickly verified there was no smoke or fire in any lavatory or in the cabin. We had leveled off at 5;000 ft per our clearance. We had no indications of anything malfunctioning or fire in the cockpit. I again verified with the flight attendants that there were no signs of smoke or fire. We then consulted with the QRH and there was no guidance found concerning lavatory smoke; fire; or false alarms. We decided to declare an emergency as a precaution and return to the airfield. We proceeded to the airport and decided to hold since there was no physical evidence of smoke or fire and agreed it was a false warning. We held for a about 10 to 15 minutes over the airport to reduce to below max gross landing weight to ensure no structural damage would be caused due to a false warning. We were holding directly over the airfield if any additional fire or smoke indications should arise; providing an alternate plan if needed. After landing maintenance personnel determined it was false lavatory smoke alarms. Hopefully guidance could be included within the QRH concerning lavatory smoke; fire; or false alarms.

Original NASA ASRS Text

Title: MD80 flight crew was informed by the Flight Attendants that two lavatory smoke alarms are going off with no detectable smoke. The crew elected to return to their departure airport after holding to land below maximum landing weight.

Narrative: Shortly after gear was retracted during a normal takeoff the Flight Attendants chimed us stating the lavatory fire detection system in the aft lavatory was alarming. Seconds later a second alarm began to ring; but this time in the forward lavatory. The Flight Attendants quickly verified there was NO smoke or fire in any lavatory or in the cabin. We had leveled off at 5;000 FT per our clearance. We had no indications of anything malfunctioning or fire in the cockpit. I again verified with the Flight Attendants that there were no signs of smoke or fire. We then consulted with the QRH and there was NO guidance found concerning lavatory smoke; fire; or false alarms. We decided to declare an emergency as a precaution and return to the airfield. We proceeded to the airport and decided to hold since there was NO physical evidence of smoke or fire and agreed it was a false warning. We held for a about 10 to 15 minutes over the airport to reduce to below Max Gross Landing Weight to ensure no structural damage would be caused due to a false warning. We were holding directly over the airfield if any additional fire or smoke indications should arise; providing an alternate plan if needed. After landing Maintenance personnel determined it was false lavatory smoke alarms. Hopefully guidance could be included within the QRH concerning Lavatory smoke; fire; or false alarms.

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.

Attributes
ACN	912899
Time
Date	201010
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	MD-83
Operating Under FAR Part	Part 121
Flight Phase	Takeoff
Component
Aircraft Component	Toilet Smoke Overheat Fire Detectors & Warning
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Pilot Flying Captain
Qualification	Flight Crew Instrument Flight Crew Multiengine Flight Crew Flight Instructor Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 105 Flight Crew Total 7900 Flight Crew Type 2700
Events
Anomaly	Aircraft Equipment Problem Less Severe

MD80 flight crew was informed by the flight attendants that two lavatory smoke alarms are going off with no detectable smoke. The crew elected to return to their departure airport after holding to land below maximum landing weight.