Date: 201902
Local time of day: 0001-0600
Location: SDF.Airport, KY
Weather elements / visibility: Clear
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B SDF
ATC / advisory: TRACON SDF
Second aircraft: B757 Undifferentiated or Other Model
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Human factors: Fatigue; Situational Awareness; Communication Breakdown; Distraction
Anomaly: ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Wake Vortex Encounter
Detector: Person Flight Crew; Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert
Contributing factors: Environment - Non Weather Related; Human Factors; Procedure
Primary problem: Human Factors

Narrative: Without question; I was fatigued after a very long day. Not only was it a 5 leg day; each leg was delayed followed by a quick turn. However; I believe that the majority of the reason this incident occurred was due to improper/lack of vectoring and clearances from ATC. As far as I remember; upon being given that 080 heading to enter a left base for [Runway] 35L; we were never given an approach clearance or told to 'join the localizer 35L'. Therefore; we were technically correct in resuming the 080 heading; even if it took us through the localizer. The next instruction was a 310 heading; cleared for the visual Runway 35L approach. The distraction of the wake turbulence and inquiring ATC for additional spacing distracted me from noticing on my PFD that we were about to fly through the localizer of 35L; putting us on a course to encroach on the [Runway] 35R approach. I believe my fatigue plus the distractions resulted in me failing to notice that we were about to fly through the localizer; which normally I would have inquired ATC about. If an approach clearance and/or a 'join the localizer' clearance was actually given with the 080 heading to join a left base for [Runway] 35L; then I completely missed that clearance and I would without question blame my personal fatigue on missing such a clearance. However; I fully believe that I was never given that clearance or any similar clearance.On approach into SDF; they were landing north. Last leg at the end of a 5 leg day which had encountered quick turns and/or delays on all 5 legs. We were assigned [Runway] 35L on the FRIZN4 arrival. Upon being given a 080 heading to turn left base for [Runway] 35L; we encountered wake turbulence generated by a 757. The Captain asked me to radio ATC to ask for additional spacing. During this very short time; we had flown through the localizer for 35L without being given additional vectors; without being told to 'join the localizer 35L'; nor being cleared for a visual approach to 35L. This had resulted in us beginning to encroach on the 35R approach. We were given a 310 heading to rejoin the localizer and cleared for the visual 35L approach. Traffic was also called out that was on the 35R approach; which I had in sight. We were instructed to maintain visual separation from that traffic. Additional traffic was called out; but I never located that traffic. We landed without incident. After landing and receiving taxi instructions from Ground Control; we were given a phone number to call from ATC. The Ground Controller said there is no paperwork or pilot deviation that'll be reported; just that TRACON wanted to know what had happened. The Captain called the number; and from what I was told; the person he spoke with wanted to ensure that even with it being a visual approach; we had set up for an ILS or other instrument approach as if we were landing in instrument conditions. The Captain assured them that we had - and always do - back up our visual landings with instrument approaches; per our company's SOP.Eliminating 5 leg days sounds like a good start. I think 4 legs should be the maximum amount of flying allowed per day by regulation; but of course that would only be in a perfect world. Cockpit distractions are almost always the contributing factor in deviations from course/altitude; but as I said before; I think very minimal blame in this occurrence rests on the flight crew. Cockpit distraction of the wake turbulence was the result of missing the fact that we had flown through the localizer. But the lack of a 'join the localizer' or a 'cleared for the visual approach' clearance - as far as I remember; was never given.




Synopsis: EMB-145 First Officer reported a track deviation occurred on approach to SDF; with the reporter citing fatigue and a wake encounter as contributing factors.