B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 129
Distraction; Situational Awareness; Workload
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Human Factors
Approaching the FUZZY intersection on the SUNST3 Arrival; we were told to maintain current heading for vectors to Runway 1L. I centered up the heading bug and selected HDG SEL and immediately began to fumble with the EFB as we had not briefed this approach (as we were expecting Runway 25L). As we began to brief the new approach and the First Officer was looking at the landing numbers on the OPC; the aircraft began to turn slightly to the left as apparently LNAV was still engaged as we passed over FUZZY. Just about then ATC gave us heading to fly further to the right.Task saturation was definitely a factor in this case as there were many things that needed to be done on short notice. I was also concerned about high terrain at night and staying in the Class B airspace surrounding it. The Class B was of particular concern as ATC was pushing hard for a visual approach; the DME on the LAS VOR was out of service and we were in a 737 with no map mode or any way to clearly define the airspace boundaries! Next time I think I'll just request the runway we had already briefed as it was favorable for the winds and was advertised as the landing runway on the ATIS.
B737 Captain reported a track deviation on approach to LAS as a result of high workload related to a late runway change.