Date: 201912
Location: ORD.Airport, IL
Aircraft: B737-900
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B ORD
ATC / advisory: Tower ORD
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Human factors: Workload
Anomaly: Deviation - Altitude Excursion From Assigned Altitude; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Unstabilized Approach
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Returned To Clearance
Contributing factors: Aircraft; Airport; Human Factors
Primary problem: Human Factors

Narrative: I (FO (First Officer)) was PM (Pilot Monitoring). Arrival to airport began with a late brief; somewhat late checklist calls and cabin PAs. ILS capture issues due to distance. Autopilot was actually steering the wrong way. Quickly realized the issue; but had trouble getting back into LNAV for better course tracking since it had already 'captured'. Still high and quite a ways out; had safe time and distance and altitude to solve the issue. Vertical deviations throughout this approach were minor; lateral deviations more pronounced. Deviations were called and were responded to by PF (Pilot Flying); always in the appropriate magnitude and direction. Despite this; there were many overshoots. They were not sustained overshoots. I strongly suspect ground aircraft intrusion into the ILS safety zone on taxiway could be the cause of needle fluctuations and subsequent chasing by PF in order to keep it 'corralled'. ATIS advertised 6SM BR OVC250. I found the conditions to be much closer to MVFR; with low clouds beginning to form near the airport. Airport was in sight around 2000 agl. Lost sight of airport around 1800 agl down to 1200 agl. During this time; lateral instability increased. Deviations called and responded to appropriately; but with overshoots. Energy state was always safe and we were vertically stable. Airport was in sight; aircraft fully configured; and lateral corrections in progress by 1000 agl. Stable all axes by 500 agl; and landed in the touchdown zone on speed.I replayed this approach in my mind many times and referenced the FOM and FH. I came to the following evaluation: scan policy was followed; stabilized approach criteria and configuration were met by the appropriate gates; and the next gate was continuously achievable; bracketing corrections due to conditions were correct and overshoots were not sustained. 500 agl to touchdown was stable and landed on speed in the touchdown zone. Approach callouts were not made except for 'landing' as I (PM (Pilot Monitoring)) was in tunnel vision on monitoring path.All this being said; as I believe we followed all policy and met all gates; for me this approach felt like the least successful of all my time at (airline); as it was near max tolerance several times; which is just so out of the norm for me. Hence; I decided to fill out this [report].As PM; I should have been more assertive in prompting briefs and checklists at the standardized times. Considering the 'feel' of the approach; I should have called for a go around when sight of the airport was lost. And I should not have missed the approach callouts.




Synopsis: B737-900 First Officer reported a safe landing followed a challenging approach that involved a number of lateral and vertical deviations that were within allowable limits.