Date: 201510
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Night
Aircraft: Regional Jet 200 ER/LR (CRJ200)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Climb
Airspace: Class B ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Powerplant Lubrication System
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Distraction; Confusion; Communication Breakdown; Physiological - Other; Workload; Time Pressure
Anomaly: Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Automation Aircraft Other Automation; Person Flight Crew; Person Flight Attendant
When detected: In-flight
Result: Flight Crew Returned To Departure Airport; Flight Crew Took Evasive Action; Flight Crew Landed in Emergency Condition; General Maintenance Action; General Flight Cancelled / Delayed
Contributing factors: Human Factors; Aircraft
Primary problem: Aircraft

Narrative: Immediately after takeoff a light smell of burning oil enveloped the cockpit. At approximately 2;000 feet; the 'Smoke Toilet' caution message came on. I request a level off at 3;000 feet from ATC while the First Officer completed the smoke toilet checklist. The First Officer contacted the Flight Attendant to tell her of our situation and have her check the lavatory for any signs of smoke or fire. That's when the flight attendant told us that the cabin had a strong burning smell and the lavatory smoke detector was sounding. After checking the lavatory the flight attendant called to tell the First Officer that yes the alarm had 'gone off ' (sounded and still sounding) but did not see any smoke in the lavatory or cabin but a strong burning smell was still present. The First Officer thought that the fire extinguisher in the lavatory had 'gone off' or extinguished and a fire had been put out. I had already requested an immediate turn back to the airport. We briefly discussed landing over weight contacted the dispatcher and I decided to land over weight because of the uncertainty of the origin of the burning smell. Tower turned us back around for a landing. On our turn back on final the 'Smoke Toilet' light went out. The landing was uneventful at approximately 48;450 LBS at a descent rate of 200 FPM. As a precaution I requested that the firetrucks follow us to the gate. After parking; I asked the fireman to come on board and check the lavatory for us. They reported no fire in the lavatory. Even after our third aircraft swap of the night the passengers thanked us; when getting off the plane; for landing (even though the flight was cancelled) because they said they could not breathe in the cabin. One passenger stopped me in the concourse going home to tell me 'The burning smell caused a breathing irritant almost like a chemical burn'. Maintenance came on board. Verified the smell in the cabin but did not find any evidence of fire in the Lavatory and told us that the extinguisher had not discharged. The evidence suggests the smell was almost certainly burning oil coming from the air conditioning ducts. I must say that even with all the delays; aircraft swaps; maintenance issues; hot airplane; unruly passenger on previous aircraft; and the air turn back; the flight attendant and the first officer held it all together; were very professional; prompt; and cordial considering the circumstances. I commend them!Miscommunication when First Officer thought the flight attendant said that the fire extinguisher in the lavatory had 'gone off' or extinguished and a fire had been put out.My misinterpretation of what was really the origin of the smell. It was a burning oil smell; not something that is normally associated with the lavatory fire. But my information was that an extinguisher had been discharged in the lavatory. It's not that I didn't think of the A/C duct as the cause; it's just that I thought that something else might also be going on at the same time and since the flight attendant said that the smell was strong and people were complaining about breathing I thought it was best to land.It's difficult to say what we could have done differently because the time was so compressed. But I think the most important thing is to make sure that we question each other more and don't assume what you think the other person said; but go slowly and methodical in our questioning of the other person to better get a better understanding of what is really happening. I let myself get out of the loop with the First Officer and the flight attendant; but I had to fly the plane; communicate with ATC and make the proper decisions with the information available. Most likely a nice quite downwind to landing at normal weight would have been just fine; but who knows.I find the company training more than adequate to handle an event like this.




Synopsis: A CRJ-200 returned to land immediately after takeoff because of a burning oil odor which made breathing difficult and actuated the lavatory smoke alarm.