Light Transport
Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 150; Flight Crew Total 15000; Flight Crew Type 4000
Communication Breakdown; Distraction; Human-Machine Interface; Situational Awareness; Troubleshooting
Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew FLC Overrode Automation
Aircraft
We were issued the infamous RUUDY 6 Departure from TEB. We briefed the procedure in detail and both of us had recent experience flying it. However; the PF [pilot Flying] is relatively new to the airplane and is wary of using the automation. He was a little timid in making the initial level-off at 1;500 at the WENTZ intersection. I believe the FMS calculated that we would not arrive at WENTZ by the required 1;500 feet and commanded the flight director to initiate a left 360 degree turn in order to cross WENTZ at the required altitude. The PF started to fly the flight director. I noticed that he was starting a left turn while the CDI was showing the correct track to WENTZ off the right. I said 'fly the course' and he thought I was saying 'fly the guidance.' We were approximately 0.5 miles left of course (1/2 scale deflection on an RNAV 1 procedure) by the time he realized what was happening and made the proper correction to get back on course. At that time Teterboro Tower also commanded a right turn and handed us off to New York Departure. We were then assigned a heading of 270 degrees and broken-off of the RUUDY 6 SID. The problem we encountered is well known with the Honeywell Epic FMS. They published a 'PIREP' in April of 2019 to explain the issue in detail. We even discussed the possibility during the pre-departure briefing. However; the PF was still blindly following the incorrect FMS guidance instead of looking at the correct CDI indication to stay on the correct course. There was a lot happening on the SID due to the low altitude level-off and the potential for inaccurate FMS guidance. We will be using the automation in the future to relieve some of the workload and allow both pilots to monitor the aircraft path/track.
Light Transport Captain reported continuing navigational problems with this avionics package during this departure.