Date: 201910
Local time of day: 1801-2400
Location: RDM.Airport, OR
Flight conditions: VMC
Weather elements / visibility: 10
Light: Night
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class E ZSE
ATC / advisory: Center ZSE
Second aircraft: Any Unknown or Unlisted Aircraft Manufacturer
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Confusion; Communication Breakdown; Situational Awareness
Second reporter function: First Officer; Pilot Flying
Anomaly: Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Executed Go Around / Missed Approach
Contributing factors: Airspace Structure; Human Factors; Procedure
Primary problem: Ambiguous

Narrative: ATC cleared us for the ILS to Runway 23 into RDM in VMC conditions. Seattle Center advised us to cancel on the ground and frequency change approved. I was the PM (Pilot Monitoring) and made numerous position calls on the CTAF frequency for a straight in Runway 23 landing. There was Aircraft Y reporting in the area as well. He stated that he was 4 SM north of the field and would over-fly the airport and extend downwind and wait for us to land. Conditions were Night VMC calm winds; 10 SM visibility; 30.35. As we continued [on what] was a visual approach; I noticed that Aircraft Y was not where he was reporting; 3 mile final; Runway 29. Instead; he was almost over the threshold as we were the same. At that point I called out 'Go-around' and the PF (Pilot Flying) executed the procedure and made the call outs. As we turned to the northwest; I noticed that there was other traffic on TCAS southwest of our position as well although we never heard from them. As we climbed up to altitude; I was communicating with Aircraft Y and making CTAF callouts. At this point it was my assumption that we were essentially VFR in VMC conditions and we made the CTAF callouts and joined the right downwind for another visual approach to the same runway. We completed the pattern and landed without further incident.Once on the ground we contacted Seattle Center to advise and they stated that there may have been a pilot deviation because we didn't fly the published MAP and did not contact the Center to advise. Once at the gate; I contacted the Center watch desk and spoke to the Supervisor who then stated that since I was on an ILS and not a visual; I needed to fly the MAP and contact them for instructions. He stated that he would be making a report and asked for my information which I supplied.RDM airport is usually busy at this time with GA traffic and numerous aircraft are usually in the area going to different runways. In this case Aircraft Y gave incorrect information which almost caused a collision on intersecting runways. My frustration with the other pilot and the gravity of the situation contributed to my omission to contact the Center on the missed approach/go-around. On top of that we had been in visual contact with the airport for 20+ miles and had forgotten that I was not on a visual and was in fact on the ILS.Apart from having an open Control Tower which can provide separation and active instructions; I need to be aware of the clearance given and the full procedure to follow in the event of a missed approach/go-around.


Second narrative: ATC cleared us for the ILS to Runway 23 into RDM in VMC conditions. Seattle Center advised us to cancel on the ground and frequency change approved. Captain briefed me on the threat of GA traffic late at night in the RDM area. He was extra vigilant during the approach making several callouts to the area to make sure we were situationally aware. Captain monitored his position while Aircraft Y overflew the airfield and entered the downwind for the intersecting Runway 29. Aircraft Y reported a 3 mile final as we approached the threshold. Captain kept vigilance on his position and noticed that Aircraft Y was actually over the threshold instead of the 3 miles out he had reported. Captain notified me and I executed the missed approach. We initially followed the procedure. Captain then began to advise we should enter into the downwind and to resume traffic pattern under his assumption we were in VFR conditions on a VMC day. We continued around for another approach and landed with no incident. Seattle Center then advised us we were to proceed with the published MAP as opposed to the pattern that we flew.The RDM airport is uncontrolled and is usually busy with GA traffic at this time as the flight schools operate at night. Aircraft Y approaching Runway 29 gave incorrect position reports. After he had landed and we had executed the go-around; he then stated that his intention was to land and try [to] stop short of our runway. This oversight of the Aircraft Y pilot could have caused a catastrophe. We were already over the threshold when the decision was made to execute a missed. As Pilot Flying I executed the missed approach and initiated the appropriate callouts. My attention was fully focused on the duties of flying the plane and making sure that everything was going to procedure. The combined factors of having to execute a go-around; trying to maintain situational awareness to terrain and other VFR traffic in the area; and trying to comply with the MAP; led to a higher workload. The Captain begin to suggest headings to enter the downwind which at the time made logical sense as we had been visual for quite some time and it made sense to do so in order to continue a safe flight. We both omitted the fact that we were supposed to contact Seattle Center and continue flying the missed approach procedure.Apart from having a Control Tower that can provide separation and runway assignments. I should have taken a moment to verify with the Captain that we; in fact; should be on a visual missed approach. The increased workload contributed to lack of cross verification.


Synopsis: Air carrier flight crew reported not flying the published missed approach procedure to RDM airport as they performed a go-around to avoid conflicting traffic.