Date: 201604
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: IMC
Weather elements / visibility: 2
Light: Daylight
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Air Conditioning Distribution System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Attendant
When detected: In-flight
Result: Aircraft Equipment Problem Dissipated; Flight Crew Landed As Precaution; Flight Crew Returned To Departure Airport
Contributing factors: Aircraft; Weather
Primary problem: Aircraft

Narrative: Climbing out of 10;000 ft a FA called to inform us of a smoke smell and visible smoke in mid to aft cabin. She said she saw a 'fog like' smoke that smelled like 'burnt plastic; burnt paint; burnt chemicals.' We did not see or smell anything in the cockpit. We advised ATC and shot the ILS. Upon landing we asked the FAs if they still smelled anything. They said no; so we went to the gate and had the equipment follow us and standby while we assessed at the gate. There were no smoke indications at the gate. A logbook entry was made for the cabin smoke and overweight (17;000 pounds; smooth touchdown) landing.We did not don oxygen masks and smoke goggles; since we had no indications of smoke in the cockpit. Our priority was to set up properly for a quick; safe return; under adverse weather conditions. We were prepared to don them immediately at the first indication of smoke in the cockpit. Under the circumstances they would have been an unnecessary distraction. I believe this went about as well as possible. The FO and the FAs handled the situation in a calm and professional manner. I did not hear of any unexpected complaints from the Passengers. Afterwards; the FO; our offline cockpit jumpseat rider; and myself; discussed the issue of not donning masks. We all agreed that under those conditions we'd made the right decision.


Second narrative: Our flight pushed from the gate approximately 2.5 hours late. I was the PM; and this was the first leg of a four-day trip. The Captain and I had flown a trip together previously. It was the first flight of the day for the aircraft. We had an offline Pilot riding in the cockpit jumpseat. After departure we were climbing out on the Departure and at about 12;000 ft; we received a call from the FAs which was answered by the Captain. When he returned from the call; he asked the jumpseat rider; and me; if we smelled any smoke. Neither of us smelled anything unusual. The Captain informed us that the FAs smelled smoke in the aft cabin. We decided to and request vectors to return. The Captain; and I; agreed that if we saw or smelled any smoke in the cockpit; we would don our oxygen masks and smoke goggles immediately. We leveled off at approximately 15;000 ft. After receiving a clearance to descend and vectors back; at the Captains request; I began loading the FMS with the ILS approach. After I loaded the approach and set both NAV frequencies and course selectors for the approach; I pulled out the QRC. I found the Smoke; Fire or Fumes Checklist. We were already diverting; the first item on the checklist. We had also decided to leave our masks off until we could see; or smell smoke; or fumes in the cockpit; so I put the QRC away and grabbed the QRH and put it in my lap. I then began coordinating with ATC. I gave them fuel on board; our requested runway; etc. We received multiple vectors and descents for the approach. I quickly typed an ACARS message to Dispatch; letting them know we were returning; due to smoke in the cabin. We continued to configure the aircraft; run checklists; and prepared to land. We discussed the fact that we would be landing overweight; and decided to pull off the runway after landing; and reassess the smoke situation with the F/As at that time. As we were turning final; just outside the final approach fix; I realized I wouldn't have time to run the QRH Checklist. I put the QRH away; and double checked our configuration; frequencies; and began performing the normal Pilot Monitoring duties. We landed without incident. The Captain talked to the FAs after we cleared the runway and they agreed there was no need to evacuate. We returned to the gate and deplaned the aircraft.


Synopsis: B737 flight crew was informed by a Flight Attendant during climbout that they smelled smoke in the mid-cabin and there was a visible haze. The crew elected to return to the departure airport and landed overweight with the smoke having dissipated during the approach.