Narrative:

The event occurred due to a mechanical failure that had grounded the aircraft prior in the day. It was signed off by maintenance and didn't fail or have any irregularities until the vector to final. While being vectored on base to final my pfd and mfd suddenly had red X's over the systems associated with the ahrs; and the autopilot disengaged. I handed off the controls to the first officer since his data was present; and compared it to the standby instruments. We asked to get vectored around to buy us time and run the applicable QRH checklist prior to going IMC. The checklist was run and instructed me to use the reversionary button to give me cross-side ahrs data. We let ATC know we were ready and continued the approach once it was safe and the situation was under control.the aircraft was written up and I filed a report. My chief pilot called me to say there may have been a pilot deviation reported by ATC. I was not aware if we had descended or [had] not been at the prescribed speed during the event and ATC made no mention of it at the time. The event happened during a vector for final so I could see how my ahrs failing would cause a deviation at a crucial time. There really wasn't anything that could have been done differently. The situation was at an awkward moment in the terminal area but all procedures were complied with and the flight was completed safely. I wish ATC would have let us know we had deviated at the time. But I'm sure they were busy accommodating us and coordinating the other traffic. They were very helpful otherwise.

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Original NASA ASRS Text

Title: EMB-145 flight crew reported a failure of the Captain's attitude instrument just at localizer intercept.

Narrative: The event occurred due to a mechanical failure that had grounded the aircraft prior in the day. It was signed off by Maintenance and didn't fail or have any irregularities until the vector to final. While being vectored on base to final my PFD and MFD suddenly had red X's over the systems associated with the AHRS; and the autopilot disengaged. I handed off the controls to the First Officer since his data was present; and compared it to the standby instruments. We asked to get vectored around to buy us time and run the applicable QRH checklist prior to going IMC. The checklist was run and instructed me to use the reversionary button to give me cross-side AHRS data. We let ATC know we were ready and continued the approach once it was safe and the situation was under control.The aircraft was written up and I filed a report. My Chief Pilot called me to say there may have been a pilot deviation reported by ATC. I was not aware if we had descended or [had] not been at the prescribed speed during the event and ATC made no mention of it at the time. The event happened during a vector for final so I could see how my AHRS failing would cause a deviation at a crucial time. There really wasn't anything that could have been done differently. The situation was at an awkward moment in the terminal area but all procedures were complied with and the flight was completed safely. I wish ATC would have let us know we had deviated at the time. But I'm sure they were busy accommodating us and coordinating the other traffic. They were very helpful otherwise.

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.