Super King Air 350
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Rotorcraft
Flight Crew Last 90 Days 60; Flight Crew Total 9000; Flight Crew Type 1150
Time Pressure; Confusion
Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew FLC Overrode Automation
Human Factors; Aircraft
I was PIC of a multi piloted King Air 350 on an IFR flight from to HEF. The departure; enroute and enroute descent portion of the flight was uneventful. We obtained ATIS at HEF and proceeded on the Arrival. Prior to BRV VOR; approach advised us to expect the GPS RWY 34R approach. We selected and loaded this approach on our recently installed Garmin 1000 FMS system. We selected BRV as the IAF since it was on the STAR. Prior to BRV; Potomac approach cleared us direct to (IF) HANOK which we selected and proceeded to this point. Potomac approach had not cleared us for the approach 5 miles from HANOK so we inquired about this. We were directed to descend from 3;000 feet to 2;000 feet and intercept the final approach course. Between HANOK (IF) and PEZSY (FAF); we were cleared for the approach and directed to contact the tower. At this point we activated the approach on the Garmin 1000 and selected approach arm on the auto pilot. (Per our training; we did not arm the approach until we were cleared for the approach by ATC.) The aircraft immediately started a left turn to the southwest toward the BRV VOR vice continuing on final approach course. Maintaining 2;000 feet; I deselected the auto pilot and attempted to fly the inbound course heading. I directed the SIC to select PEZSY and give me a Direct To this fix so I could have navigational guidance. As he was attempting to accomplish this; tower directed us to turn left to 120; maintain 2;000 and contact Potomac approach. I assumed we flew outside the approach corridor as the auto pilot was attempting to take us to BRV VOR. After composing ourselves as to why we were taken off course with an unexpected left southwest turn; we followed approach's vectors. During the vectors; we received the dreaded phone number to call upon landing. In the process; we reprogramed the FMS for vectors to final for the GPS RWY 34R approach. We flew the vectors provided by Potomac Approach to the final approach course for an uneventful approach and landing. We contacted the Potomac Approach Ops Manager upon landing and gave him our information and an explanation for the event.There are a couple factors leading to this event. We had the Garmin 1000 system installed aboard the aircraft approximately 2 months prior. We received 8 hours of training on the system...as well as completing private school Garmin G1000 and Garmin 1000 online courses prior to flying the aircraft. We were well prepared to operate the system. Although we had selected HANOK as a direct-to point from the loaded approach portion of the flight plan when approach cleared us to this fix; selecting BRV prior as the IAF when we first programed the approach caused the system to turn to BRV when we armed the approach vice continuing on the final approach course. Although we tried to correct the problem when we first noticed the turn; it happened very quickly and it took time to for us realize what was occurring. With our only navigation guidance directing us to BRV; we could not correct back to final approach course. KUDOS to tower and approach for timely monitoring; recognizing we were experiencing navigation difficulties and directing us to a vector and altitude to attempt the approach again.We plan to correct this in our flight department G1000 procedures by only loading vectors vice an IAF in our FMS unless we are specifically directed to proceed to an IAF in our approach instructions from ATC. This was a very attention getting and disconcerting experience which I hope never to repeat again.
Utilizing a newly installed Garmin 1000 GPS the flight crew of a Super King Air 350 set up for the RNAV (GPS) 34R approach to HEF.  Improper sequencing of other waypoints when 'direct to clearances' were provided by approach resulted in a course reversal turn back to BRV; the planned IAF; and possible penetration of R-6608C just southwest of the inbound course.