Air carrier flight crew reported a lavatory smoke warning message during descent. A flight attendant reported smoke was seen in the forward lavatory. Smoke worsened during descent; therefore after landing a precautionary evacuation was completed.
Synopsis
Air carrier flight crew reported a lavatory smoke warning message during descent. A flight attendant reported smoke was seen in the forward lavatory. Smoke worsened during descent; therefore after landing a precautionary evacuation was completed.
Narrative
Precautionary evacuation due to SMOKE FWD LAV" warning and Flight Attendant information. While descending well into the arrival; we received a "SMOKE FWD LAV" warning message. We also heard the beeping from the smoke detector in the main cabin. The Captain initiated me to run "SMOKE FWD LAV QRH." Shortly after turning to the QRH Checklist page; ATC gave us instructions preparing us for final vectors to land. It was at this time we let ATC know we had an issue and relayed the message we received. The Captain instructed me to [request priority handling] with ATC. ATC responded and asked how many souls and pounds of fuel onboard. I let them know that information; and the Captain got a call from the Flight Attendant believing they could smell a slight burning smell from the front lavatory area. In addition; the "SMOKE FWD LAV" warning message extinguished. After he gathered this information from them; I returned to the QRH. However; both the Captain and I agreed due to our low altitude and workload management getting the aircraft ready for landing; it would be best to both focus on configuring the aircraft safely. He transferred controls to me while he made maybe one or two more calls to the flight attendants; and coordinated with ATC for response. Landing was uneventful. ATC asked if we would like to taxi off or if the trucks should come to us. ATC said it is no problem for the trucks to come to us; and we said to standby while we checked in with the Flight Attendant on the situation. The forward Flight Attendant said; "The smell is getting stronger." I relayed this to the Captain and he said we will be evacuating here. He instructed me to begin the Evacuation Checklist which then triggered the evacuation. Evacuation happened without incident or injuries."
Second reporter narrative
On approach for landing; Passenger A used the forward lavatory. While in the lavatory the smoke detector went off for about 15 seconds. Passenger A did not come out right away - maybe XX-XY seconds after smoke detector stopped. When they came out; there was a cloud of smoke that followed the Passenger. I even noticed it coming from their hair as they sat down. I immediately questioned if they were smoking. They said; No." I explained that the only time the smoke detector goes off is because there is smoke. They asked if it was a malfunction - I said no. I asked them if they could see any smoke coming from anywhere in the lavatory or smell smoke. They said; no. I asked aft FA (Flight Attendant) to check for any signs of smoke or fire in the lavatory and to check the halon to see if it went off/activated. I asked Passenger A if they were vaping. They said no. I could smell smoke - not cigarette smoke; but smoke from something burning. The aft FA said that the halon is still in normal mode; she checked for fire and hotspots and didn't find anything. But she said she could smell smoke too. I also checked for hotspots; smoke and fire in the lavatory and in the galley service area.Within minutes of the smoke detector sound stopping; the Flight Deck; FD; called and told aft FA we have a priority situation. Aft FA told me that the Captain was unclear in his description. I called to verify/confirm. Captain said that; "We have a priority situation - we got an alert indicator of smoke in forward lavatory and that emergency personnel will meet us upon landing on tarmac. Prepare for normal landing. Standby for further instructions." I said that I believed a passenger was smoking in the forward lavatory. Aft FA and I were in process of putting service items away when all of this happening. So we quickly secured the galley and then I made the preparation PA. Right before touching down; the smell of smoke became stronger; but no visible smoke. We landed and stopped on tarmac. I waited for direction from Captain. He called and said emergency personnel are on their way and to wait to open the door. I said that the smell of smoke got stronger. He then said we're going to evacuate. After what seem like a long 1 - 2 minutes he made PA "Evacuate!" The power was off; so I began to yell at the passengers to "come this way - evacuate now!" Passengers began grabbing their belongings; so I yelled; "LEAVE EVERYTHING; EVACUATE; COME THIS WAY!" Passengers were evacuated within XX -XY minutes. I went to Passenger A and asked them if they were using any kind of spray. They said no. Everyone was accounted for with no injuries."
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.