Flight Crew Air Transport Pilot (ATP)
Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Flight Crew Landed As Precaution; Flight Crew Diverted
Aircraft
During cruise flight; at FL330; the Flight Attendants called the Flight Deck and informed myself and the First Officer that there was a noticeable odor in the cabin; and the odor appeared to be getting stronger. The First Officer and I began reviewing the Cabin Fire/Smoke Checklist. The Lead Flight Attendant called the Flight Deck again and stated that the cabin lights had been turned off; and the odor had dissipated rapidly. The Cabin Crew suspected that there might be a problem with one of the ballasts. The odor never returned during the rest of the flight.After some time had passed; we were informed by the Cabin Crew that the aft left lavatory was very hot; and the walls and floor of the airplane in that area were too hot to even touch. They advised that they could feel the heat of the floor through their shoes. After receiving this information; I told the Flight Attendants to keep me advised of any changes; I transferred controls to the First Officer; and then I declared an emergency with ATC and asked for their help in finding a nearby suitable diversion airfield. I then made a PA to the passengers that we would be executing a landing in [a nearby airport]; and to follow the instructions of the crewmembers. We descended and landed normally; and we had [emergency services] inspect the exterior of the aircraft. The [emergency services] Captain advised me that through infrared he could see large heat signatures in the back of the aircraft; in particular; he advised that the bags in the aft cargo compartment appeared to be glowing. Once [emergency services] advised that the aircraft was cleared; and the Flight attendants reported that there were no adverse changes in the cabin; we proceeded to the north transient ramp and deplaned via the forward stairs; with [emergency services] continuously standing by and monitoring. More effective aircraft maintenance and inspection procedures.
MD-80 Captain reported diverting to an alternate after heat and odor were noticed in the cabin.