Narrative:

Was enroute to teb via the LVZ3 arrival. Had received left and right turn vectors for spacing after jhw VORTAC; was subsequently cleared direct hoxie and the remainder of the LVZ3 arrival. Pilot monitoring entered 'direct hoxie' into the right hand FMS and executed the flightplan change. FMS's had been sync'd the whole flight and remained so subsequently. LNAV was coupled to the pilot flying (left) side that had 'FMS 1' as the selected navigation source. Aircraft tracked to hoxie. A short time after crossing hoxie; while crew was conducting descent checklist items; ny center called to verify we were proceeding direct to lvz. Two heads snapped up to observe a) LNAV was annunciated in the EFIS lateral FMA (flight mode annunciator) window; b) autopilot was coupled to flight director 1; c) left side (flight director 1) navigation source was FMS 1; d) FMS CDU showed 'from:dir'(in white); 'to:hoxie'(in magenta); e) EFIS plan view showed aircraft position to be east-northeast of hoxie intersection; on the north side of the charted course from hoxie to lvz. Crew did not check if either FMS CDU annunciated 'inhibit' (meaning inhibiting of automatic waypoint sequencing; i.e. FMS would not sequence to next leg of the flight plan if 'inhibit' were active/annunciated). I immediately 'closed up' the flight plan by placing hoxie in the FMS CDU 'from' field; which moved lvz into the 'to' field; and executed the flight plan change; whereupon the aircraft entered a right turn to establish and intercept of the charted course between hoxie and lvz. At no time in the flight did the crew deliberately push the 'inhibit' lsk (line select key) on either FMS nor was there a 'discontinuity' displayed anywhere in the flight plan. It is possible that 'inhibit' was pushed inadvertently and not noticed; or that the procedure is incorrectly coded in the database; or that there was some other FMS malfunction.

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Original NASA ASRS Text

Title: A CL604 experienced a track deviation when the FMC failed to track the cleared course.

Narrative: Was enroute to TEB via the LVZ3 arrival. Had received left and right turn vectors for spacing after JHW VORTAC; was subsequently cleared direct HOXIE and the remainder of the LVZ3 arrival. Pilot monitoring entered 'direct HOXIE' into the right hand FMS and executed the flightplan change. FMS's had been sync'd the whole flight and remained so subsequently. LNAV was coupled to the pilot flying (left) side that had 'FMS 1' as the selected NAV source. Aircraft tracked to HOXIE. A short time after crossing HOXIE; while crew was conducting descent checklist items; NY Center called to verify we were proceeding direct to LVZ. Two heads snapped up to observe a) LNAV was annunciated in the EFIS lateral FMA (flight mode annunciator) window; b) autopilot was coupled to flight director 1; c) left side (flight director 1) NAV source was FMS 1; d) FMS CDU showed 'FROM:DIR'(in white); 'TO:HOXIE'(in magenta); e) EFIS plan view showed aircraft position to be east-northeast of HOXIE intersection; on the north side of the charted course from HOXIE to LVZ. Crew did not check if either FMS CDU annunciated 'inhibit' (meaning inhibiting of automatic waypoint sequencing; i.e. FMS would not sequence to next leg of the flight plan if 'inhibit' were active/annunciated). I immediately 'closed up' the flight plan by placing HOXIE in the FMS CDU 'FROM' field; which moved LVZ into the 'TO' field; and executed the flight plan change; whereupon the aircraft entered a right turn to establish and intercept of the charted course between HOXIE and LVZ. At no time in the flight did the crew deliberately push the 'INHIBIT' LSK (line select key) on either FMS nor was there a 'discontinuity' displayed anywhere in the flight plan. It is possible that 'INHIBIT' was pushed inadvertently and not noticed; or that the procedure is incorrectly coded in the database; or that there was some other FMS malfunction.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.