Date: 201702
Local time of day: 1801-2400
Location: ZZZ.ARTCC, US
Flight conditions: IMC
Weather elements / visibility: Icing; Turbulence
Light: Night
Aircraft: Regional Jet 900 (CRJ900)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Second aircraft: Widebody Transport
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Second reporter function: First Officer; Pilot Flying
Anomaly: Conflict Airborne Conflict; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Detector: Automation Aircraft TA; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Separated Traffic; Flight Crew Took Evasive Action
Contributing factors: Airspace Structure; Human Factors; Procedure
Primary problem: Procedure

Narrative: Once climbing through 10;000 feet I accomplished my flow of turning off the applicable lights and moved the sterile switch to the off position. At that time I informed the First Officer (FO) who was pilot flying that I was going to go off com 1 to communicate to the FA's that we were going to be possibly heading into turbulence for an unforeseeable amount of time. If I remember correctly ATC had notified us earlier that we were in an area of possible moderate precipitation. Once the FO confirmed he had com 1 I immediate called the Flight Attendants (FA) on the PA/Call function to inform them that I felt it would be unsafe for them to get up and begin a service based on current conditions (rain; beginning of light turbulence). After we were briefly discussing the details on how notification to begin service would begin I immediately switched back to Com 1.Upon returning on frequency I remember hearing the altitude alerter going off and I notice the FO was in a descent to 11000 from an altitude that I can't specifically remember as I also noticed an amber TCAS message and if I remember correctly he was also communicating with ATC all at about the same time. I inquired about what has happen since my absence (30 seconds max). He explained that we slightly went above our assigned altitude and that we had gotten a vector from ATC because of our proximity to another Aircraft. I inquired ATC about the incident and asked if we needed a number to talk about the situation. After she communicated with what I assume was a supervisor she told us that due to an alert on her end we did. We eventually received a number to call and continued the remainder of the flight without incident.As stated above I had not noticed until returning to com 1 which by then the event had already occurred.I am honestly unsure. Communating with the Flight Attendant about the change from normal operation due to a safety concerned diverted my attention just long enough from the initiation of a level off at 11;000 feet that I have no recollection of the precise causes of the event.I do believe the weather played a factor as conditions were well beyond a standard day being that it was night; IMC; icing; precipitation and turbulent.I was trying to catch up to current events.I could have possibly waited until a positive level off at 11;000 feet. But at the same time I still felt that the Saftey and Communication with my crew was also a top priority at the time. Minus the weather a level off was the last was only clearance we had left to accomplish at the time.


Second narrative: Overview: Had an altitude deviation on initial level-off at 11;000 feet; which created a yellow traffic alert with Aircraft Y aircraft. The event lasted about 30-45 seconds.I was the First Officer (FO)/Pilot Flying (PF) on this night; last leg of a four-day trip. Thunderstorms were moving through the area; especially directly in our route of flight east of ZZZ. Took off from runway XY; and was given an initial course vector of 050 degrees; then a climb to 11;000 feet. Autopilot was off. In IMC from 1000 feet to well past the event. At 10;000 feet; the Captain (CA)/Pilot Monitoring (PM) did his flow then asked me to take the radios because he had to warn the FAs about mod precip and possible turbulence expected shortly. I acknowledged and almost immediately was given a 'direct [ZZZZZ Intersection]' call from departure. I immediate selected direct [ZZZZZ Intersection] in the FMS; hit NAV mode and autopilot ON. I checked to see if the CA was watching me do this to confirm the FMS change; but he was still busy with the Flight Attendant (FA) call. At the same time I was tracking a yellow traffic target on TCAS that was ahead and left few miles; about 1000 to 1200 feet above. I saw the ALTS CAP message on the PFD for 11;000. Just then ATC gave me a traffic callout for the Aircraft Y; the same target I had been seeing on TCAS. Because of the quickness of all of those events happening while being PF and working the radios & FMS; and watching the traffic getting closer laterally and now at 1000 feet above (zooming in on the MFD); I forgot to reduce thrust out of CLMB as the autopilot started to level at 11;000 feet. I then noticed the altitude still rising to 11;200 and ATC gave me a turn to 25 degrees right to avoid the traffic. I immediately reduced thrust and the altitude began to settle back down to 11;000 feet. The Aircraft Y got a traffic alert; and did we; no RA's. ATC questioned us on our altitude and I told her I was going back down to 11000 feet as we turned away from the traffic. At some point during this; the CA/PM had gotten off the call to the FAs. We talked about what had just happened and continued the flight uneventfully. The CA/PM did; however; inquire immediately from ATC if she had a phone number for us to call; but they didn't seem too concerned. She did explain that she had no feedback from her side; but that her system had sent an automated message to a Center about the loss of separation/traffic alert. We inquired again; but didn't get a phone number until several minutes later. The CA called Center after we landed.Other factors involved were weather and the Intercom Communication System (ICS). Weather concerned and distracted us and also created a bumpy ride in IMC while getting St Elmo's Fire on the windscreen. It also was the reason the CA had to call the FAs at 10;000 feet; which started the chain of events. The ICS became an issue for me because the CA did not deselect his hot mic while talking to the FAs; which made the radio calls harder to hear and created more distractions.I'm not sure what more I could have done differently looking back; besides maybe turning on the autopilot earlier when I entered IMC. The events happened so fast (~30-45 seconds) that not having the CA handling the radios and FMS; and me flying; getting multiple calls; looking for traffic; changing waypoints in the FMS and leveling off was just a task saturating event. Those things led me to miss reducing power in the level-off; which in turn over-whelmed the autopilot in leveling off from a high climb rate at high thrust. I also believe that ATC could've done better in not vectoring me directly into the lateral path of the Aircraft Y since I was climbing vertically towards him too.


Synopsis: The flight crew of a Bombardier CRJ-900 reported that they neglected to reduce thrust and passed through the assigned altitude resulted in requiring a turn to avoid traffic.