Narrative:

Noted burning smell in cockpit at rotation. At approximately 400 ft AGL received a lav smoke warning on EICAS. Requested a return for landing; stated nature of emergency and declared emergency. About 2 minutes later the lav smoke warning went out. Landed on 27R; exited the runway; set the parking brake and completed the lav smoke checklist. Crash fire rescue equipment was waiting and boarded the aircraft to investigate. Found everything ok; smell was dissipating; crash fire rescue equipment exited aircraft and followed us to the gate. Entered acrid smell and lavatory smoke during rotation in logbook. No known injuries. Weather was clear.

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Original NASA ASRS Text

Title: Air carrier aircraft returned to departure airport under emergency conditions when a LAV SMOKE EICAS warning supported a burning smell.

Narrative: Noted burning smell in cockpit at rotation. At approximately 400 FT AGL received a LAV SMOKE warning on EICAS. Requested a return for landing; stated nature of emergency and declared emergency. About 2 minutes later the LAV SMOKE warning went out. Landed on 27R; exited the runway; set the parking brake and completed the LAV SMOKE checklist. CFR was waiting and boarded the aircraft to investigate. Found everything OK; smell was dissipating; CFR exited aircraft and followed us to the gate. Entered acrid smell and lavatory smoke during rotation in logbook. No known injuries. Weather was clear.

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.