Date: 201211
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: MD-83
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Human-Machine Interface
Anomaly: Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Crew; Person Flight Attendant
When detected: In-flight
Result: Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; General Maintenance Action; General Declared Emergency
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: On climbout at approximately FL180; we began smelling a strong odor of smoke. Shortly; the flight attendants advised there was also a strong smell of smoke in the cabin. We leveled the airplane at our cleared altitude of FL190 and; immediately afterward; the flight attendants advised the First Officer there was now quite a lot of smoke in the back of the cabin and that they could see the smoke move around when they waved their hands through the air. I declared an emergency with ATC and requested an immediate return for landing. The Controller told us to maintain FL190 while she coordinated with another Controller for a lower altitude. My First Officer said that the smoke was getting worse and we needed to return for landing immediately. I exercised emergency authority and told ATC we were vacating our assigned altitude and needed a clearance to return for landing as soon as possible. I suspected the smoke may have been coming from the air conditioning packs so; before descending; I reached up and turned the auto temperature controllers to 'cold' and switched both air conditioning supply switches to HP Bleed Off. I noticed that the Flow light came on when doing this and decided to turn them back to auto. There was no annunciation on the Electronic Overhead Annunciator Panel (EOAP) at any time and no master caution.We both took out our smoke goggles and got the oxygen masks ready for use but; because there was no smoke in the cockpit and wearing them made it more difficult to perform our duties; we elected to keep them by our side ready for use if needed. I also asked the First Officer to read the emergency checklist for smoke in the cabin which we then completed. We then re-contacted ATC who cleared us direct to our departure airport as we continued our descent for landing. We completed the return and the approach checklists as Air Traffic Control asked for souls on board and fuel remaining. The First Officer then contacted Operations and notified them we were returning. Descending through approximately 12;000 FT we noticed that the smoky smell had dissipated. The First Officer called the Flight Attendants who confirmed the amount of smoke in the cabin was also dissipating. We told Air Traffic Control that we were still an emergency aircraft; but that the smoke in the cabin was clearing. They asked if we still wanted emergency vehicles when we landed and we responded in the affirmative. We received vectors for the ILS 29; shot the approach and landed normally. The rest of the flight was uneventful. We told ATC that we were able to taxi to the gate under our own power. We asked that the emergency vehicles follow us to the gate just to be on the safe side. We pulled into the gate; shut down the engines and deplaned the passengers without further incident. By the time we arrived at the gate; the smoke had completely dissipated in the cabin. I contacted Dispatch; then the duty pilot; and then Maintenance Control and explained what had happened. There was no further incident with the flight.




Synopsis: An MD-83 flight crew declared and emergency and returned to their departure airport when smoke and smoky odors were detected in the cabin and cockpit.