Citation Excel (C560XL)
Flight Crew Air Transport Pilot (ATP)
Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway; Ground Incursion Taxiway
Air Traffic Control Issued Advisory / Alert; Flight Crew Took Evasive Action
Airport; Human Factors
Crew was given clearance to taxi from the Cessna service center via G;B;N to runway 30L.  I put our taxi clearance in the scratch pad before taxing.  We started to taxi and I asked my F/O if he knew where he was going  he said 'he did.'  I then said I was inside and I started my taxi checks.  When I got to the ant-ice checklist; I was distracted and concerned about the system not working correctly.  The day before we had multiple  malfunctions with the system.  My F/O said out loud 'I don't see Bravo.'  He then asked if we were cleared to cross?  I answered 'Yes.'  In my mind I thought we were cleared all the way to 30L.  I then asked where do we turn right on 'bravo?' and he answered 'At the end somewhere.'  I then went head down in the cockpit at that time to finish the taxi checks.  ATC then asked us to stop as my F/O was stopping also. We had crossed the hold short line on the end of 12R by an airplane length at most.  We turned around and stopped the plane.  Made sure with ground where 'B' was located.  Ground gave us a phone number to call after the flight  We continued the flight with no other events.  I want to note that the temp in the cockpit was 101 degrees with limited airflow.  We had diverted the plane the day before with electrical and anti-icing malfunctions.  We had been on duty sitting for nine hours prior to flight.  Also crew had been on early shift all three days prior to flying on the later schedule.  Both crew members are East Coast; based on the West Coast.  We had been working very well as a crew all week.  This miscommunication and event was 'no way' intentional.  There were a lot of factors involved.  I spoke with the supervisor of the IWA tower.  She told me other pilots have struggled with the taxi clearance as well and she thought the taxi area should be an incursion area.
ATC issued taxi clearance G B N to 31L (I heard 31R) [30L/30R].  PIC read back clearance; noted GBN in FMS scratch pad.  SIC performing taxi.  Coming out F; I (SIC) started to query the PIC on the strangeness of departing from a far runway (31R) when he voiced something we had discussed earlier about the anti-ice check that he was performing.  My query was forgotten (change of subject) and I was busy looking for the taxi signage.  Merging onto G I was looking for a sign for B but saw none; only for G and Y.  The PIC asked if I knew where I was going.  I interpreted this as 'do I understand the clearance?'; when this is not what he meant.  I said yes.  Approaching the 30L hold short bars; looking down the runway for traffic; I said 'I don't see B are we cleared to cross (31L)?' (knowing there was a taxiway on the far side of 31R; I assumed that must be B) He replied; 'Yes.'  He misunderstood what I was asking.  As we started across the hold bars; PIC asked 'when do we turn right?'  Before I had time to respond; ATC issued a 'stop' command; which I did.  I had crossed the bars perhaps 20 feet; turned around and exited 30L.  There was no traffic conflict.  It was only after I stopped that I looked back and further down the taxiway did I see a sign for B; which you cannot see unless you are past it from the direction I was coming out.Assume less and communicate more clearly.  Unless there was a sign neither of us saw; coming out from the Cessna Service Center on F; where you merge onto G (first part of the clearance); the sign for B is behind and to your right about 200+ feet.  Better signage would certainly significantly decrease the likelihood of a recurrence.
CE560 Flight Crew describes a runway incursion at IWA.