Commercial Fixed Wing
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Training / Qualification; Communication Breakdown; Distraction; Situational Awareness; Time Pressure
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Overrode Automation; Flight Crew Returned To Clearance
Environment - Non Weather Related; Human Factors
The flight was worked by myself/CA as the PM and the FO as the PF. Both of us are reserve pilots and haven't flown very much this year. Extensive ground delays combined with multiple weather reroutes caused us running 3.5 hours behind schedule. We ended the day with 11.8 hours duty and approximately 8 hours flight time after factoring in a maintenance test run prior to our turn. On the arrival we were assigned delay vectors for Runway XXC due to ZZZ airport's wind shear concerns. We continued to plan accordingly. Visual conditions in the ZZZ terminal area; current speed was 220 knots; approach cleared us down to 3;000 feet and 030 heading. Shortly after they asked if we had the field in sight. We confirmed; then they cleared us for the visual approach Runway XXC and gave additional instruction to slow down to 160 knots. The PF called for Flaps 8 and then Flaps 20 at appropriate speeds. As we continued to slow down; he contemplated a need for flaps 30. Due to it being almost XA PM; the flight deck was dark; so I grabbed the speed cards and turned on my chart holder light to verify if we needed flaps 30 to stay above maneuvering speed. I noted flaps 20 provided a 4 knot buffer above slowest maneuvering speed; however; the flight conditions caused some light turbulence stemming from gusty wind conditions. The PF called for flaps 30 to provide a bigger margin of safety above Va. Unfortunately; as I got distracted with our Va and speed cards previously mentioned; I failed to notice that the APPR mode was not armed. As result; staying in HDG mode and distracted we flew through the Localizer. Approach called and queried us on our flight path. The PF disengaged the autopilot and corrected back without delay while I responded to ATC that we're correcting. The PF landed the aircraft shortly after without any further irregularities. Despite a warranted concern to make sure we're at a safe speed for the given aircraft configuration; I let myself become distracted with said task and should have done better dividing my attention. As soon as the words 'cleared for the approach' are broadcasted; focus should shift to the FMA by both pilots for confirmation that APPR Mode is armed.
Air Carrier Captain reported a track deviation and cited lack of flying by both pilots contributed to the event.