Gulfstream G650
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 54; Flight Crew Total 10391; Flight Crew Type 88
Human-Machine Interface; Confusion
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance
Flight Crew FLC Overrode Automation
Human Factors
ATC held us up past our top of descent. Issued a clearance to descend via an RNAV arrival. Descent was going to require a descent in excess of 3;000 FPM. In a rushed mode in order to make the descent I quickly spun the vertical descent knob on the autopilot control panel the wrong way and engaged. Airplane started an aggressive climb. I disengaged the VS mode spun the descent mode in the correct direction and reengaged. Airplane did not respond and kept climbing. Disengaged autopilot; started the descent and informed ATC.
On our flight we were filed for FL410 and climbed to FL450 due to turbulence. We were filed and cleared for the RNAV arrival. Shortly prior to the beginning of the published arrival we were cleared to descend to FL240. FO initiated a descent to FL240 using the autopilot. We were level at FL240 for a short period when were issued a clearance to 'descend via' the RNAV arrival. The final altitude on the arrival is 4;000 feet. This was confirmed by FO and myself; and I set 4;000 feet in the altitude preselect. FO then requested a 'vertical direct to' an intersection altitude on the arrival. I informed him there was not a published altitude for this intersection; but there was an altitude published for [the next intersection] and asked if he would like a 'vertical direct to' [that] altitude? He responded; 'yes'. I went heads down to program the FMS for his request.When I was done programming the FMS; I looked up and saw the aircraft was in a climb; climbing through approximately 24;800 feet. In addition; I noticed FO's hand on the vertical speed dial with a 2;500 FPM climb dialed in and he was continuing to dial a greater climb. I immediately informed him 'we need to descend'. He did not reverse his actions; in fact increased the vertical speed to 3;500 FPM climb; thinking he was initiating a descent. I then told him; 'you need to disconnect the autopilot and descend!' He said 'no; I will just dial it back down'. We are now climbing through approximately 25;500 feet. I said again; 'you need to disconnect and descend!!!' Finally; approaching FL260 he disconnected the autopilot and descended. I immediately made a radio call to Center that [we] had climbed and we are back descending for the arrival. The response from Center was 'roger' and no other comment was made. VNAV was reengaged and we descended on the arrival.The only lesson learned here is the PF needed to have a better understanding of the autopilot; flight guidance panel; FMS and situational awareness.
Pilot flying selected a climb vice a descent on the vertical speed dial.