Date: 201910
Local time of day: 1201-1800
Location: ZZZZ.Airport, FO
Flight conditions: VMC
Weather elements / visibility: Thunderstorm; Turbulence
Light: Night
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; First Officer
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Troubleshooting; Workload; Distraction; Situational Awareness; Time Pressure; Human-Machine Interface; Communication Breakdown
Second reporter function: Captain; Pilot Flying
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown; Inflight Event / Encounter Unstabilized Approach
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Regained Aircraft Control; Flight Crew Became Reoriented
Contributing factors: Weather; Human Factors; Equipment / Tooling; Aircraft
Primary problem: Aircraft

Narrative: Captain was Pilot flying; and I (First Officer) was Pilot Monitoring. First leg of a 4 day sequence. Flight was uneventful until arrival -to-approach phase into ZZZZ. Night flight isolated thunderstorms; with moderate turbulence. We were cleared for the STAR; ILS DME Runway XX. During before landing checklist the recall step turned our attention to a Pack light that had temporarily illuminated and created a distraction in the cockpit; it was determined it was illuminated for temporary changes in duct pressure. Now below 10;000 ft. MSL; once cleared for the approach; pilot flying set up the mode control panel automation for an ILS approach. It is unknown whether the event occurred because of automation malfunction or self-induced automation errors that occurred as a result from the aforementioned distraction. This led to a situation where we were temporarily without proper navigation indications. Lateral mode had reverted to control wheel steering in the roll mode. Pilot monitoring lost flight director indications. Pilot flying was able to restore glide-slope indications on pilot flying side. In an attempt to restore proper navigation indications to both pilots displays; the pilot monitoring told the Captain: 'hey let's level off; tell ATC and get a turn out and fix this automation'; followed by 'hey time-out' 'I'm not comfortable lets figure this out'; and finally I spoke directly to ATC and requested a turn to holding to troubleshoot the problem; but aircraft did not because the Captain told me to tell ATC that we were continuing. We were able to restore partial navigation indications to the Captain side of the cockpit. The Captain was determined to continue the approach in an effort to safely land with working but degraded navigation equipment. I tried to encourage the Captain to discontinue the approach and restore proper navigation displays to both sides while in holding. It is important to mention that we were carrying plenty of ferried fuel to divert: we had all the time necessary to fix the problem (we landed with 12;000 lbs. of fuel; or approximately 2 hours of fuel). I believed that discontinuing the approach and going to holding to be the safest course of action. I utilized all cockpit resource management strategies to help the Captain make the right decision to discontinue the approach and go to holding to restore proper navigational inputs to both displays. After exhausting all efforts to do this; and being told to tell ATC we are continuing; I helped the Captain make the best approach possible. I had to be very directive on configuration and airspeed. Additionally; I am writing this report because it is unknown if we were fully flap configured by 1;000 ft. AGL. In any case; not having flaps in the fully configured landing position we should have executed a go-around; I as Pilot Monitoring should have called for the go-around when it was not executed by the Captain. However; I feel it necessary to mention that I am not confident the Captain would have responded to my go-around call as I had exhausted all attempts to help him discontinue the approach earlier. Other than the flaps; we were stabilized and I did not want to have to wrestle the pilot for the flight controls if he decided to not go-around. Under the circumstances I felt that a stabilized landing was the safer option; and ultimately it is what occurred.This event occurred when a distraction led to an error being introduced to the mode control panel. It is unknown if it was crew or navigational degradation that caused this loss of navigational display. This led to a situation where we were temporarily without proper navigation indications. This event was further compounded by the Captain's resistance to suggestions from the First Officer (myself) to discontinue the approach in an effort to fix unknown navigational issues. I think we should further emphasize the use and implementation of protected phrases; example: 'I'm in the yellow; I'm in the red.' And how unfamiliar crews can better communicate when there is high task loading.


Second narrative: During the STAR to ZZZZ we encountered weather and moderate turbulence which resulted in the aircraft arriving high to start the ILS DME Runway XX approach. The autopilot was on with LNAV being the active lateral mode and with the localizer mode armed for capture. I believe that the active descent mode was flight level change. As we were in the turn or just prior to the turn to intercept the localizer the FO (First Officer) did a recall check which resulted in the left pack light remaining illuminated. This resulted in a momentary distraction as we tried to determine the cause of the light. It seemed to be the result of a momentary split in duct pressure. By the time that I returned my attention to the approach I realized that the autopilot lateral mode had downgraded to CWS (Control Wheel Steering) and we had not captured the localizer and in fact were deviating north of the localizer. Initially I was startled about the situation and I disconnected the autopilot and reengaged it in an attempt to regain lateral guidance; but that attempt was not successful. The remainder of the flight occurred without any flight director or HUD lateral guidance. Not knowing what was causing this set of circumstances and fearing that an attempt to go around might result in a go around with no lateral guidance for me and with the FO's flight director still inoperative; I made the decision to continue the approach to an attempted landing. The approach was not a stable approach as I was correcting for a high start and was referring to my Navigation Display for lateral guidance and of course hand flying the approach. The approach was not comfortable to me and as this was the FO's first flight into ZZZZ it certainly wasn't comfortable to him. We successfully acquired the runway and were able to land; but it was by no means a good approach. That being said while it was certainly not a stable approach I felt not knowing if would have had lateral guidance during a go around which turned toward high terrain justified the unstable approach from which we could have still initiated a go around if we could not get into a position from which a safe landing on the runway could be made.Obviously my high start to the approach made it more difficult; but I have no idea why we lost the FO's flight director and my lateral guidance.


Synopsis: B737-800 flight crew reported multiple instrument failures that resulted in an unstabilized approach.