Flight Crew Flight Instructor; Flight Crew Flight Engineer; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 75; Flight Crew Total 20000; Flight Crew Type 4700
Communication Breakdown; Workload
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown
Flight Crew Requested ATC Assistance / Clarification
Human Factors
Approach from the west on the arrival; on IFR flight plan; in VFR conditions; planning a visual landing on Runway 29.Aircraft is equipped with [a] FMS system. Regular copilot was not available for trip; so I was flying with a contract pilot in right seat who; it turns out; did not have complete mastery over the [FMS] system. Therefore; I had to do most of the programming of the FMS; and I did program the reference STAR.Near ZZZZZ intersection; we were given a heading change for traffic; and a descent clearance to 3;000 ft. I switched from NAV to HDG mode; complied with turn; and started the descent. Believing that we were no longer required to track on the arrival route; I selected 'direct ZZZZZ' (fix on the Runway 19 ILS approach course); inserted the inbound course; and executed the command. The result; which was expected; was that the course and fixes that were previously displayed on the MFD disappeared; and were replaced with a depiction of the final approach course fixes and runway.Shortly thereafter; the approach controller asked if we were proceeding to ZZZZZ. I replied that we were not and asked for a vector. His reply was 'no problem'; and he gave us the vector.The reason I asked for the vector was that it was a very busy time in the cockpit; the copilot was having trouble re-programming the FMS for the ZZZZZ One Arrival; I didn't have time to do it while managing the flying duties; and it seemed to be the best course of action.My recommendations are: 1. To not change FMS programming from 'arrival' to 'approach' mode until you ascertain that you have been cleared off the STAR; and 2. To make sure that your fellow pilot is fully qualified in the operation of your NAV equipment.
General Aviation Jet Captain on Standard Terminal Arrival Route proceeded to the Initial Approach Fix before being cleared off the arrival. The Aircraft had been given a heading for traffic.