Date: 201812
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Aircraft: Regional Jet 900 (CRJ900)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Anomaly: Flight Deck / Cabin / Aircraft Event Passenger Misconduct
Detector: Person Flight Attendant; Person Flight Crew
When detected: Aircraft In Service At Gate
Result: General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: The FO (First Officer) and I went to ZZZ and we were running behind due to crew swap as we were both on Airport Ready Reserve. We knew that a change of aircraft was going to take place as well as a crew swap with new flight attendants once we arrived in ZZZ.While the passengers were deplaning from the flight [to ZZZ]; I elected to deplane and move to the other plane at the other gate.When I arrived at the gate the gate agent was frazzled; and came to me stating that she started boarding the [next] flight without the pilots because the flight attendants were there and ready to bring passengers on the plane. I said that is fine; but then she said that she stopped boarding because one of the passengers opened the over-wing exit door. I told her that it was good to stop boarding; and that I would make an announcement to the passengers in the jetway; and on the plane to move back to the boarding gate area and off the plane. I made an announcement to all the passengers in the jet-way to head back to the boarding gate area. Once on the plane I asked the forward Flight Attendant what happened and she confirmed the gate agents' words. As I looked back to the aft Flight Attendant; she looked worried and not happy. I immediately made an announcement thanking the passengers for their cooperation and informed them that we would need to deplane and take all of their belongings with them back to the boarding gate area. I related the need for safety and that an inspection was needed for the over-wing exit door by a qualified maintenance individual. Everyone deplaned and then I was able to move to the exit row; see the over-wing exit door sitting on the seat; and get the complete story from the aft Flight Attendant in the presence of [a Company staff member] from ZZZ.After hearing the cause; I called Dispatch; and had them stay on the line as we spoke with Maintenance Control. We spoke with [Maintenance Control;] and informed them about what happened. He said that an inspection was needed and a possible pressurization check might need to happen. He coordinated local maintenance from ZZZ; and I went to the Gate Area to let the gate agents and the passengers know what was happening; and that this might take a while to complete. I also reiterated the importance of safety; and that this kind of behavior was not acceptable; and how it impacts everyone; passengers; crew; and others at other airports. All of the passengers were thankful and many shook my hand. When local maintenance arrived they inspected the door; and relayed to me that a pressurization was not needed. They signed to maintenance log and we proceeded to [our destination.] The flight attendants did not want the passenger or the passenger's friend on the flight. She mentioned this in front of the [Company staff member]; and he mentioned that they were already removed from the flight; and mentioned that they might be on the 'no fly' list moving forward. I agreed with not letting these 2 individuals back on the plane; and I fully supported the flight attendants' wishes.All passengers deplaned and I moved to the exit row where the Flight Attendant and the [Company staff member] were waiting. I saw the exit door sitting in the seat. I asked her what happened and she explained.This report from the Aft FA (Flight Attendant) [describes the cause:]There were 2 guys that boarded the plane and it appeared that they were in the bar before the flight as it was delayed. They were loud and talking back and forth. One of the passengers was approximately 2 rows forward of the other sitting in the exit row. He mentioned 'hey dude you are in the exit row;' and the other said 'ya; I am going to keep you safe dude. I have got this and it is my responsibility to keep everyone safe on this plane; man.' At this time the flight attendant came forward and said; I am glad that you are taking your responsibilities seriously in the exit row. She was doing this to confirm that she was hearing slurring words coming from this man and she wanted to be closer to him. Immediately after she said this to him he said; 'oh; ya; I got this; I know exactly what to do.' Immediately he pulled the exit door handle and removed the over wing exit door. This all happened while the FA was saying 'Nooooooooo!' At this point she told him to put the door on his seat and remain there. She called the forward Flight Attendant and let her know what happened and she informed the gate agent to stop boarding immediately.I came on the plane shortly after this. Both FAs did not want these 2 individuals on the plane due to safety concerns and I agreed.




Synopsis: CRJ-900 Captain reported being informed during passenger boarding that a passenger opened the Emergency Overwing Exit door.