Date: 201706
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Regional Jet 200 ER/LR (CRJ200)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach; Final Approach
Airspace: Class B ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Oxygen System/General
Component problem: Design
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Distraction; Situational Awareness; Workload
Second reporter function: Pilot Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown; Inflight Event / Encounter Bird / Animal
Detector: Person Flight Crew
When detected: In-flight
Result: Aircraft Aircraft Damaged; Flight Crew Took Evasive Action; General Maintenance Action
Contributing factors: Procedure; Human Factors; Environment - Non Weather Related
Primary problem: Human Factors

Narrative: On final; shortly after autopilot was disconnected a mosquito appeared in the cockpit. This was a great distraction to my First Officer (FO) who was pilot flying. They repeatedly tried swatting at the mosquito while hand flying the aircraft. I grabbed the rolled up release and smashed the mosquito so that my FO would no longer be distracted. After swatting the mosquito a ding was heard for caution message and the caution switch light illuminated. There was a PAX OX ON message. I instructed the FO to continue the landing. After exiting the runway and completing the after landing check I instructed to the FO to speak with the Flight Attendant (FA) to assess the situation. We continued to the hold pad since our gate was not open. In the hold pad I spoke with the FA about the passengers and the masks. She informed me that no passenger donned the masks as she made an announcement that they had deployed in error. Once our gate opened we taxied over and deplaned the passengers. All passengers appeared in good spirits despite the wait in the hold pad and the masks. I notified Maintenance of the deployment and they arrived at the aircraft. I informed them of what occurred and showed them that the guard did not function properly to protect the switch from inadvertent activation. The cause of this event was the distraction caused by the mosquito in the cockpit and the failure of the switch guard on the passenger oxygen switch. More training or awareness that this switch guard failure is a known issue and to avoid the switch as much as possible or refit or repair those guards which do not function properly.


Second narrative: During the final approach phase as the Pilot Flying I identified a mosquito in my field of view. It is my understanding that the Pilot Monitoring attempted to remove the Mosquito from my field of view. During this attempt; the Guarded Passenger oxygen mask switch was inadvertently contacted issuing a single chime followed by a yellow master caution 'Pass Oxy on'. We continued without incident given the nature of time associated with the threat. Captain notified Maintenance on landing. The cause of the event is the Crew's untimely handling of removing the mosquito from the field of view. Follow Company SOPs to avoid participating in activities or resolving issues in the cockpit while in the approach phase of flight unless such issues become a flight risk or pose a safety risk to any or all persons on board.


Synopsis: CRJ 200 flight crew reported accidentally deploying the passengers oxygen masks after being distracted by a mosquito in the cockpit.