Date: 201209
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Night
Aircraft: MD-82
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class E ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Air Carrier
Reporter function: Pilot Flying; First Officer
Reporter qualification: Flight Crew Commercial
Human factors: Distraction; Time Pressure; Troubleshooting; Situational Awareness
Second reporter function: Pilot Not Flying; Captain
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Flight Crew; Person Passenger; Person Flight Attendant
When detected: In-flight
Result: Flight Crew Took Evasive Action; Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; General Declared Emergency
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: During initial climb flight crew; cabin crew and passengers detected strong odor. It was quickly determined that no smoke or toxic fumes appeared to be the cause. We initially thought it might have been a blown tire and since the odor persisted the Captain elected to declare an emergency and return to the departure airport. We maneuvered east of the field to lose altitude and made an uneventful landing. We were inspected by Airfield Rescue and Fire Fighters and escorted back to the gate.


Second narrative: After takeoff I heard multiple cabin chimes going off in the cabin (probably over 30 chimes) followed by a call to the cockpit by the flight attendants. Both pilots also (at the same time) noted a very strong odor. (The odor in the cockpit dissipated very quickly) flight attendants confirmed a very strong odor in cabin; no smoke; no haze; no fumes detected. Asked if they could define the source; and the #1 responded 'No'. Told First Officer to keep flying; take the ATC radios; and get us turned back toward the departure airport. I declared emergency; requested immediate return to the departure airport; briefed the flight attendants; told them we would be landing in 5 minutes and do their quick review though I suspected no need to evacuate at that moment due to the fact they said they thought the smell was 'going away.' Regardless; requested emergency equipment to meet the jet when we cleared our landing runway. Also gave a brief PA to the passengers. The flight attendants reported that the passengers all subsequently remained very calm; and followed all instructions. First Officer landed the jet; without incident. Taxied clear; Airfield Rescue and Fire Fighters inspected exterior of aircraft; noted nothing out of the ordinary. #1 Flight Attendant reported no more odor in the cabin. [We] taxied to the gate. The 3 flight attendants performed flawlessly; giving me good information and inspecting the entire cabin in just a few minutes; trying to identify the source of the odor. They also handled our passenger very well.

Second callback: The Reporter is uncertain what the odor was and when he asked five people; including the flight attendants; how they would describe the odor he got five different answers. One of the answers was a hydraulic fluid odor. He has not followed up with his Company to see maintenance findings. If he had to make an educated guess he would say odor's source was an air conditioning duct.

Synopsis: A strong odor was detected by a MD-80's pilots; flight attendants; and passengers after takeoff so an emergency was declared and the flight returned to the departure airport.