EMB ERJ 135 ER/LR
Flight Crew Air Transport Pilot (ATP)
Situational Awareness
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; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Aircraft
Inbound on the DRLLR 1 arrival into Houston the FMS/autopilot failed to sequence past the DOMNO fix.  When reaching this fix; the plane automatically disengaged LNAV and went into basic roll mode instead of making the required turn.  Right as this happened I turned the plane back to intercept the arrival and my First Officer re-engaged the nav function of the autopilot and we reintercepted the arrival. Had we both not been watching the airplane that closely we could've had a fairly significant deviation at a lower altitude over the top of a busy airport.  As it was; as Houston Approach called to verify that we were making the turn; we were already in the turn back to course.  Approaching that point there was not a single sign in the flight plan or the FMS or on the course depiction on the ND that the airplane would not make a turn as expected.
EMB-135 Captain reports that the autopilot failed to turn over the DOMNO fix as programmed; during the DRLLR 1 RNAV arrival to IAH. The deviation is immediately detected and corrected.