Date: 202011
Local time of day: 1801-2400
Location: MSO.Airport, MT
Flight conditions: Marginal
Weather elements / visibility: Cloudy; Icing; Windshear
Light: Night
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach; Initial Approach
Airspace: Class D MSO
ATC / advisory: TRACON GEG
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Human factors: Situational Awareness; Workload
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Unstabilized Approach; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Became Reoriented; Flight Crew Executed Go Around / Missed Approach; General Flight Cancelled / Delayed
Contributing factors: Company Policy; Environment - Non Weather Related; Human Factors; Weather
Primary problem: Weather

Narrative: Upon arriving at MSO airport on [Date] at approximately XA:00 the winds were not favorable to execute the ILS to RWY (Runway) 12. The weather conditions to perform the RNAV GPS D were alternating between ceiling and visibility going below minimum conditions. We were communicating with Dispatch along the way and were discussing diverting to our first alternate; which [was] Billings (BIL). The ceiling and visibility at MSO was above minimums at time of arrival. We started the RNAV approach with a circle to land on RWY 30. After crossing the final approach fix at 6;800 ft.; and descending to our MDA of 4;700 ft.; we started to have some ground contact. The FO (First Officer) said that he saw the PAPI lights to the right of us. The approach did not allow for us to circle to land northeast of RWY 12/30. The only way to commence the circle was to fly over the airport and circle around to the west. We briefly discussed circling to the west and quickly decided that it would be unsafe to circle around the airport at night in low visibility with LLWS (Low Level Wind Shear) conditions in mountainous terrain. During the decision making phase I had inadvertently disconnected the auto throttle. We continued to the missed approach point. As we went around I had realized that the MAP fix was not in the box. As we looked at the approach plate and quickly made a climbing left turn on a heading of about 340. We asked ATC for a heading while we headed in the proper direction. Once WENKE was back in the box we realized we were right on course.At approximately 8;000 ft. we were back in radar contact and was giving a vector off the final approach course. ATC asked us if we wanted to commence another approach or divert to a different airport. After discussing the conditions that we saw and weather forecast to be deteriorating; we unanimously decided that it would be unsafe to conduct a circle to land night approach based on the current weather and forecasted conditions.We then told ATC that we were going to divert to BIL. We sent ACARS message to Dispatch telling them we were diverting as well. After landing at BIL; Dispatch told us that we were to refuel and proceed back to MSO. Dispatch then said the weather was not good enough to go back and was delaying our departure. After waiting about an hour Dispatch said the winds were improving and we should be able to do the ILS RWY 12 back into MSO. We departed BIL for MSO with BIL as our alternate if we could not get in. We executed the ILS to RWY 12. While in Billings we contacted ATC and they told us at that time that they did not have radar until about 8;000 ft. The controller said that he was not working at that time but discussed with the previous controller that we were right where we were supposed to be and we said we just were at a high work load and wanted to verify with them that we were on course.High workload with low ceilings; LLWS; at night in mountainous terrain. Having to circle with visibility below what was projected and inadvertently disconnected auto throttles to land.I feel like this approach is not a safe approach to do at night. I spoke with several carriers that land at this airport and this approach is not authorized.




Synopsis: Air carrier Captain reported difficulties while conducting a circle-to-land approach at night in mountainous terrain in low visibility conditions followed by an improperly executed missed approach.