EMB ERJ 145 ER/LR
Flight Crew Air Transport Pilot (ATP)
Distraction; Human-Machine Interface; Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Returned To Clearance; Flight Crew Took Evasive Action
Aircraft
On the MSCOT arrival at the turn onto the downwind leg at DOMNO the autopilot failed to turn; reverting into roll mode. The crew was watching; waiting for the turn and was able to use HDG mode to initiate the turn with minimal lateral deviation. ATC was immediately informed; however they were unconcerned. ATC queried the flight crew if they were operating an older model aircraft with a single FMS unit; which was a correct assumption. ATC further indicated that missing that specific turn was a common occurrence; particularly with that type of avionics configuration. No separation conflict was noted. Prior to reaching that point of the arrival; both members of the flight crew had reviewed the arrival in the FMS; and found no discontinuities; or 'ghost' fixes outlined in tech briefs.The autopilot failed to make a turn on the arrival; presumably due to a problem with the FMS database.
The Reporter does not know why these anomalies are happening. His Company is aware of them and he believed that the issue has been addressed with the FMS manufacturer. He does know that single FMS aircraft has this issue whereas dual FMS equipped aircraft do not.
A single FMS EMB-145 with the autopilot engaged flying the MSCOT 2 RNAV failed to make the turn at DOMNO and transitioned to the ROLL Mode. ATC was aware of the issue as the crew used the HEADING Mode to fly the arrival.