Flight Crew Commercial; Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Flight Instructor
Flight Crew Last 90 Days 15; Flight Crew Total 1550; Flight Crew Type 800
Human-Machine Interface; Situational Awareness
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Human Factors
Flight planned SJC VINCO V107 PXN ... During IMC climb transition to level at 6;000 MSL; TRACON assigned a heading which was essentially direct VINCO Intersection. Nearing the intersection; I was cleared pilot navigation to join V107. I (too) quickly noted position on moving map display; and then engaged GPSS and alt hold. As the aircraft began its turn; I turned to check the wings and tail for icing; as the aircraft was in cloud tops and temperature was slightly above freezing. A few moments later; I noted that the turn was continuing well beyond the expected heading; and immediately disengaged the autopilot while beginning a turn back toward the V107 course. Simultaneously; NCT TRACON called to ask heading. I confirmed the turn on course and the Controller noted that the heading had been almost the reciprocal of the expected heading. At this point; I recognized the problem. When I engaged GPSS; the GPS had not yet sequenced from the SJC-VINCO leg to the VINCO-PXN (V107) leg. The GPS was attempting to reestablish itself on the first leg inbound to VINCO; and GPSS had commanded a near-360 turn. The correction is simple: before engaging the automation; ensure you know the state of the automation.
BE35 pilot reports engaging the autopilot and GPS without verifying the waypoint after being cleared to join V107. The aircraft attempts to turn back to the previous fix (VOR) before it is detected by both ATC and the reporter.