Commercial Fixed Wing
Communication Breakdown; Situational Awareness
ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Taxiway
Air Traffic Control Issued New Clearance
Human Factors
The safety of the flight was compromised when we taxied past the approach end of [Runway] 9L in PHL on Taxiway Y. Taxi clearance was '9L; J; Y; K.' We continued south on Y instead of making the left onto K. Taxiway Y does not intersect 9L so this was not a runway incursion. Runway 9L was being used exclusively for departures; no aircraft observed on final approach at the time. Taxiway Y is very close to the approach end of [Runway] 9L. [This] could have caused the potential for a go-around or collision with an approaching aircraft had anyone been on short final. As we turned from J onto Y; the Captain commented something like 'Approach for 9L is clear; we're good to go.' I had just finished the mini brief and Engine 2 Start Checklist; looked up to see us passing K; and said 'which runway?' The Captain hit the brakes; then changed mind and continued taxiing (we were already under the approach path for 9L). I contacted Ground; told them we had passed K; and read back new taxi clearance '9L; Y; P; W.' The flight continued uneventfully. Several factors contributed: Delays caused by IFR; marginal VFR weather. Weather delayed our flight; causing pressure to get out as soon as possible. Delays throughout the system meant Dispatch had fallen behind on paperwork. [We] didn't receive ours until very late; which contributed to [our] completing tasks in non-standard order. Delayed paperwork prevented me from getting Departure Clearance at the usual time. Didn't realize I'd forgotten to get it until after pushback. At that point; I called for clearance over the radio after two failed attempts to get clearance via PDC. We quickly confirmed the Departure Clearance verbally; I had written it down; then told the Captain what we got. From there we followed procedures and SOP; both listened to taxi clearance; Captain wrote it down; we had airport diagrams out. The route was not as I had briefed; but I thought I understood where to go despite the fact that this flight was my first departure from PHL. The taxi out was rushed; the taxi route was short; there were several other aircraft trapped at their gates until we started taxiing; and we had already been delayed because of the weather and forgetting our Departure Clearance. CRM communication breakdown. Inexperienced First Officer; very experienced Captain; I may have been able to keep us from continuing under [Runway] 9L's approach path if I had said 'Stop!' as soon as I saw the Captain wasn't planning on turning onto [Taxiway] K; rather than phrasing it as a question 'Which runway were we cleared to?' CRM time on task. Adequate rest the previous night; but we sat in the terminal for 1.5 hours before being able to begin preflight preparations. ATC clearance taxi instructions were issued with standard phraseology; but it may have helped if the Controller mentioned 'don't cross 9L.' Taxiway signage/markings and airport diagram. Taxiway Y doesn't intersect [Runway] 9L so it doesn't have any markings or signage that indicate proximity to [Runway] 9L's approach end (is there even standard markings for that?). Airport diagram has no note or hot spot marking indicating how easy it is to miss the turn from Y onto K. It's a very fast turn. Rain was falling heavily enough that both the Captain and I needed to turn our windshield wipers on/off to be able to see where we were going. Suggestions; this incident seems to be another example of why it's better to speak up if you're not sure what's going on and to be assertive about it if you know your crewmember is doing something wrong. Hopefully awareness of this mistake will help other pilots avoid it. If there are others who have made the same mistake; then additional signage/marking on Y should be installed and a hot spot added to the PHL airport diagram. Speaking personally; I knew I was getting task-saturated; but didn't realize I was overloaded until it was too late. I will try to remember that feeling; so that I can recognize it in the future and take steps to manage the workload more effectively before something like this happens again.
[Narrative added no additional information].
Air Carrier flight crew taxiing for departure at PHL passed an assigned turn and taxied under the arrival path for Runway 9L; no traffic conflicts occurred.