Light Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP)
Human-Machine Interface; Situational Awareness; Confusion
Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued Advisory / Alert; General Maintenance Action
Aircraft
We departed PSP 31L on the Cathedral One Departure. The initial climb instructions on the departure indicate to climb heading 310 to cross the PSP R-268 then turn right direct PSP. The First Officer was the flying pilot and took off by preference in G/A mode. At 400 FT he requested Flaps/YD/NAV mode. I did all 3 items and noticed that the command bars commanded a slight (5-10 degree) turn to the left. The MFD displayed the departure correctly. However; as we continued the climb to the 268 radial; the command bars had taken us approximately 15 degrees to the left of the 310 course (however; it was following the course line correctly on the MFD). My First Officer noted this but believed the FMS was correcting for wind drift. As we approached the 268 Radial the Controller queried us if we were on the 310 heading. I responded that we were on the course and that it did appear that we were slightly left of course on a 295 heading. He confirmed that we were on the Cathedral One departure. I noted that we were close to the rising terrain to our left but not dangerously or uncomfortably so. The Universal FMS in this case shows a 310 heading and then generates a pseudo waypoint at the R-268 point then commands the right turn direct back to the PSP VOR. The Line Item on the FMS display only identifies this as the R-268 Fix. I believe the FMS programming is generating that fix in the wrong location causing the route to fly a 295 heading closer to the rising terrain. I have reported this to my Assistant Chief Pilot for a database correction. However; had we corrected the course heading and over-rode the FMS guidance to more closely follow the instructed heading; we would have avoided the incorrect course drift error. We get so used to the small differences between NAV source guidance and GPS course guidance that these errors are possible when the course error is small as in this case.
The Reporter stated that the R-268 conditional waypoint was displayed west of its actual location and this track was also displayed in the MFD. After turning back toward PSP the remaining departure track was apparently correct. The Reporter's Maintenance Department removed the Universal FMS.
While flying the PSP Runway 31 Cathedral One departure; a Universal FMS generated; and the flight director commanded; a MFD track 15 degrees left of the PSP 310 Radial but the FMS display accurately indicated the R-286 conditional waypoint.