A single FMS emb-145 with the autopilot engaged flying the mscot 2 RNAV failed to make the turn at d...

Attributes
ACN	1182730
Time
Date	201406
Local Time Of Day	1201-1800
Place
Locale Reference	I90.TRACON
State Reference	TX
Environment
Light	Daylight
Aircraft 1
Make Model Name	EMB ERJ 145 ER/LR
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	STAR MSCOT 2
Flight Plan	IFR
Component
Aircraft Component	FMS/FMC
Person 1
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types

Narrative:

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 heading 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.

Original NASA ASRS Text

Title: 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.

Narrative: 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.

Data retrieved from NASA's ASRS site 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.

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.