Challenger 300
Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 45; Flight Crew Total 8500; Flight Crew Type 600
Human-Machine Interface
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 Became Reoriented; Flight Crew Returned To Clearance
Aircraft; Human Factors
Prior to passenger boarding we briefed the MIXUT2 (6L) departure procedure.  The first instruction is to fly a 57 degree heading to 1000' msl then continue of a 57 heading and expect vectors to MOBEL. During the discussion we determined we should fly the departure in nav mode instead of heading because the vector was contained in the FMS legs page. At 1000' MSL the FMS commanded a turn toward MOBEL.  The pilot flying (PF) turned (we were hand flying; the autopilot would have done the same thing) and we were immediately questioned by Departure Control as to our assigned heading.  We confessed our turn and were vectored back to the departure course.  I believe this departure procedure (MIXUT2) is coded incorrectly in the navigation database.  There is no sequence inhibit or gap between the vector and the first waypoint (MOBEL).  The turn to the waypoint is an 'expect' only; not a fixed turn.  We have seen several sequence type errors on departures with headings in the Rockwell Collins Proline 21 avionics systems.  We have reported it to them and they say it will be 'corrected' in the next database revision.  The sequence errors keep appearing.  If we had flown the procedure in HDG the problem would not have occurred. That is our new; accepted procedure with a departure with an initial heading. We had just completed an in house RNAV/RNP/PBN training which stressed retrieving departures from the database and never to modify them. We complied with that guidence but if we would have inhibited the sequence that would have eliminated the problem as well. We trust the procedures to be correct out of the box.  Missing gaps or sequence inhibits are critical on most departures yet they are hard to find in the Proline 21 FMS leg page.Lastly as the pilot not flying (pilot monitoring) I should have stopped the PF from making the turn but I was preoccupied with traffic avoidence and gear and flap retraction.
The reporter states that it is not easy to tell if this FMS is planning on honoring a vector or is going direct at some point. The FMS will fly radar vector departures from TEB flawlessly but fails to do so at CYYZ and SDL.
CL30 First Officer states that the MIXUT2 as flown by his Rockwell Collins Proline 21 avionics system; does not maintain the 057 degree heading as required by the SID. Instead; at 1000 feet; it directs a turn direct to MOBEL. ATC detects the error.