Date: 202001
Local time of day: 1801-2400
Location: ZZZ.Tower, US
Light: Night
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class D ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: FMS/FMC
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Human factors: Situational Awareness
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Executed Go Around / Missed Approach; Flight Crew Became Reoriented; Flight Crew Overcame Equipment Problem
Contributing factors: Aircraft; Human Factors; Weather
Primary problem: Ambiguous

Narrative: An initial attempt to make the landing resulted in descent below minimums and past the point at which an extraction procedure became mandatory. The autopilot was disconnected and all appropriate calls were made; manual speeds; heading mode; and 'activate' for the pre constructed extraction procedure. When the FO (First Officer) was told to activate; all navigational functions disappeared. Within 2-3 seconds the decision was made to begin the extraction procedure per SOP. The pre-built extraction procedure and the back up waypoints were removed; uncommanded by the crew. Although terrain displays were up and functioning; the extraction and the back up extraction waypoints and guidance were not visible. As the Captain and Pilot Flying; I made the decision to follow the missed approach overlay which was still visible on the MFD and was hand flown. This was based on a risk assessment which would have involved guessing on the extraction waypoints using only terrain mapping; and in consideration of the aircraft's loading and performance which was maximized by a light payload and low temperature. Terrain high points were looked at and the published missed approach waypoints and minimum altitudes; along with the approach MSA were also considered. Improved ground visibility existed along the missed approach path; while hard IMC conditions existed along the extraction procedure. A normal diversion to the listed alternate was completed.Part of the cause is still unknown; why the waypoints and the backup fixes would disappear are not understood. It is believed that the FO hit the auto throttle button instead of the heading button at the time of commands coming when descending below minimums; which started a confusion chain reaction with both pilots; beginning with a rollback of thrust which was immediately overridden. Night conditions along with the disablement of the installed witness lights made it impossible to quickly determine the error. Having to look at the FMA to confirm flight mode activation takes eyes out of the flight deck windows and into the EFIS. At low altitude on an extraction procedure; it is impossible to do with any degree of accuracy.Both Captains and FOs should receive some simulator training for ZZZ that includes extractions; FMS failures; along with a combination of engine failures during those procedures; and in night and IMC conditions. While Captains receive a specific check out for ZZZ operations; FOs do not and frequently the Captain is completing ZZZ IOE at times when FO proficiency must not be in question. The witness 'active mode' lights should be reactivated and properly trained as they were installed by the aircraft manufacturer; most likely for a reason. Additionally; initial and recurrent training should focus on the pilot's normal bidding routes in addition to other Company and FAA mandates. It is simply useless to spend hours flying visuals into ZZZ when the pilot is based in a location and at a seniority that means they are not flying into those locations but into high mountain airports where single engine missed approaches and avionics failures are not going to be assisted by ATC. Some consideration needs to be given to a pilot's normal flying routine and made abnormal in training.




Synopsis: E-175 Captain reported executing a go-around after descending below minimums. The go-around was complicated by the unexplained loss of navigational information.