Date: 201211
Local time of day: 0601-1200
Location: EWR.Airport, NJ
Flight conditions: VMC
Light: Dawn
Aircraft: Beechjet 400
Operator: Air Taxi
Operating under: Part 135
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Ground EWR
Reporter organization: Air Taxi
Reporter function: Pilot Not Flying; First Officer
Human factors: Fatigue; Situational Awareness
Second reporter function: Pilot Flying; Captain
Anomaly: Deviation / Discrepancy - Procedural Clearance; Ground Incursion Taxiway
Detector: Person Flight Crew
When detected: Taxi
Result: Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Contributing factors: Human Factors; Chart Or Publication; Airport
Primary problem: Ambiguous

Narrative: Taxiing from the FBO to Runway 4L; we were given instructions Sierra; Bravo; Delta. While proceeding south on Sierra; we did not make the slight left turn to join taxiway Bravo. ATC gave us new instructions to turn left on Romeo Foxtrot and rejoin Bravo southbound. Factors that led to the mistake were my lack of experience at EWR airport; fatigue; and an ambiguous Commercial airport diagram. This was my first departure ever from EWR so I was unfamiliar with the airport layout. Due to the very early morning duty-on time; I was unable to obtain proper rest the evening prior. Combined with my lack of experience with the EWR airport; this contributed to my lack of situational awareness and missing the Bravo taxiway. Additionally; the Commercial airport diagram is slightly confusing. It does not clearly depict the inner and outer taxiways that surround the main terminal. The NACO airport diagram versus the Commercial airport diagram is night and day; with the NACO being far superior. An airport diagram that more clearly depicts the taxiways would be very helpful.


Second narrative: Following a busy peak travel period where we (the crew) had 3-4 days back to back with over 12 hours of duty each day flying multiple legs with quick turns or not greater than 1 hour between flights and short overnights. I had personally begun to feel fatigued towards the end of our 'duty marathon' but our aircraft was scheduled down for maintenance for several days. This day was going to be our first day without any legs since the beginning of the rotation 8 days prior. I got a call from Dispatch that they were putting us on a new tail number and they needed a 2 hour call out for a reposition to EWR for a trip the following morning. The First Officer and I left the hotel within the first hour of our call out and were not surprisingly told that our expected wheels up time was in 4 hours. Now Dispatch would like us to 'hurry up and duty off' so we can get our 10 hours of rest for a reposition the next morning. The following day we got our repo accomplished as planned but I continued to notice some signs of fatigue on my part; such as having to double check clearances and confirm; then reconfirm every little thing. Once on the ground in EWR the First Officer and I briefed how this was a complex airport and that we'd take our time with the taxi instructions and write everything down. We noticed in the FBO that the taxi looked basically like a straight shot from taxiway S down to runway 4L but it looked like that one piece of pavement was taxiway S then it turned into B then D. We received instructions to taxi via 'S B and D to 4L'. I confirmed with the First Officer who had his diagram out that we'd continue straight ahead on S and it would turn into B then D. I also knew that based on the Commercial Airport Diagram; we'd be in the outermost ring of the taxiway around the terminal; ie there would be grass on our left side but solid pavement all the way to the airline terminals. This coincided with everything we were looking at until I saw a yellow 'A' straight ahead while on S just short of RF. I stopped the aircraft and asked the First Officer to tell ATC we made a mistake and we were on S after missing the turn for B that neither I nor the First Officer were looking for. They actually called us while were waiting for a break to transmit to them and told us; 'just make the left on RF and join B there'. ATC then told us to 'contact tower and have a nice day.' We were only stopped briefly and we were not in a position to delay any ground traffic behind us. The rest of the taxi and takeoff was uneventful.There are multiple issues at play here but in my opinion the easiest way to prevent this would have been to call fatigue the previous day. Once we got called out to the airport and had to run around for a while under a fairly high stress environment I should have known a 3 am wake up would not be a good idea. Upon further review of the Airport Diagram after completing the flight the First Officer pointed out how much clearer the NOS Airport Diagram was as opposed to the Commercial Taxi Diagram. The Commercial Diagram has several taxiways bunched so close together that their identifying letters are actually offset from there actual position. There is also white shading denoting non-paved areas; this is what led me to believe I could just taxi straight ahead as there was no white shading to the right of S or B. There are however; black circles with dark grey shading inside them that is apparently supposed to mean an unpaved or grassy area. On the NOS Airport Diagram this distinction is clearly made; i.e. I would have seen that I'm not to taxi with solid pavement to my right. I am willing to admit that I could have made this taxi error even if I was at 100%; the diagram is quite confusing. I do believe that my chances of noticing the slight left turn onto B from S would be greatly increased had I been less weary from the long days. I did not include the events that led up to this event to complain about them; as you can see I wasthe one who originally proposed the early morning repo to EWR. I added them in because I see room for improvement in how we select what crews do what and when. Taking into account a crew's previous levels of activity seems prudent at this operating tempo.


Synopsis: BE400 flight crew reports missing the turn from Taxiway S to Taxiway B southbound due to fatigue and the cluttered Commercial airport diagram.