Date: 201512
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: IMC
Weather elements / visibility: Rain; 3
Light: Daylight
Aircraft: Medium Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Climb
Airspace: Class B ZZZ
ATC / advisory: Tower ZZZ
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Confusion; Distraction; Situational Awareness; Workload
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Wake Vortex Encounter; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Returned To Departure Airport
Contributing factors: Human Factors; Weather
Primary problem: Human Factors

Narrative: We met the previous crew when we took over the aircraft. The Captain mentioned that one of the engines seemed to have vibrations but was within limitations. The flight departed the gate on time and taxied for departure. Conditions at the airport included light rain; 3 miles visibility; and ceiling about 400 ft. As we pulled onto the runway; the FO turned off the windshield wipers. I told him to turn them on for takeoff for the rain. We were cleared for takeoff. I advanced the thrust levers and made the appropriate callouts. After rotation and the call of positive rate I called gear up; speed mode; nav mode. I usually call for wipers off at this point but my FO already had them turned off. It was right at this time that I hit some wake turbulence right as we were entering the clouds. It was a 10 degree roll left in attitude which I corrected for and soon I got the FMS call from the FO. I noticed there was a distinct vibration which I could feel in the yoke and that the usual attitudes I plan for on the departure were not giving me familiar climb performance. I knew something wasn't right but not sure what. I adjusted pitch attitude to compensate; called for flaps 0 after takeoff check which the FO called complete. I then called for autopilot. At this point we start[ed] discussing the vibration. Being predisposed to expecting an engine vibration I stated that there is no way this is an engine vibration. I was concerned and asked ATC to keep our speed at 200 KIAS and stop the climb at 6000 feet. I transferred the controls to my FO so I could more easily talk to ATC and work the problem. This is where I should have caught the mistake but I didn't. I called the dispatcher and told them that we had an unusual vibration and that we were returning to ZZZ. I got initials and time from them. I spoke with both the flight attendant and the passengers. I took the controls back and had the FO set up the speed; approach etc. We landed on the 45;000 lb card so there was no overweight landing. As we turned an extended base the FO noticed the gear were still down. At this point; I decided to continue the approach; land; and go to the gate for the following reasons: we were at low altitude on approach; I doubt we would have had enough fuel to continue to ZZZ1 at that point let alone if we took the time to find out if we did; I obviously was having a situational awareness issue so I asked myself what else have I missed; we were both so shocked that we missed something so basic that we were very distracted; and I felt that our safety culture always says; do not try to salvage a bad situation get yourself out of there. So with that in mind I felt it was the safer course of action to just hit the restart and start the leg over. At the gate I spoke with maintenance and told them the story. We were fueled almost immediately and had a new release very shortly after that. I did not however tell the passengers much. I kept it vague so as not to alarm them. Maintenance returned saying that we had to do a download of flight data anytime there is an air return so we did have to wait on the machine and the download during which time a few passengers decided to take a different flight. After the download was complete we pushed back and completed the flight to ZZZ1 without further incident.Threats included: first flight with a new crew; weather conditions; wake turbulence; complacency. The errors included: me; jumping to the conclusion that the vibration was what the other crew was talking about and not looking for a simpler answer; me; not taking the offer to speak with maintenance about the problem (I felt uncomfortable in the air with the feel of the plane at that point) which might have led us to checking the gear position; me; not being 'in the game' and losing situational awareness; and the FO not backing up the flow with a checklist and verifying gear handle position. I do have a theory why this happened and it is something that airline pilots have to guard against. The FO mentioned that he normally does not use the windshield wipers on takeoff. When I asked him to turn them on for takeoff and he subsequently turned them off at the positive rate call his muscle memory was satisfied that he had reached out and operated a lever albeit the wrong one. This muscle memory action coincided with the wake turbulence encounter precisely and interrupted the flow. All this being said; I am very embarrassed and will take steps to combat complacency and loss of situational awareness including most importantly slowing down and taking a step back to assess the situation.




Synopsis: CRJ200 Captain reported incorrectly attributing a vibration after takeoff as an engine issue. A clearance back to the departure airport was received; however when configuring the aircraft for landing it was discovered that the landing gear had never been retracted after takeoff and was the source of the vibration. An uneventful landing was accomplished.