EMB ERJ 170/175 ER/LR
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 100; Flight Crew Total 1750; Flight Crew Type 70
Communication Breakdown; Human-Machine Interface; Situational Awareness
Conflict NMAC; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Took Evasive Action
Human Factors; Procedure
Cleared for the ILS XXR into ZZZ. ZZZ was running simultaneous approaches to XXL as well at the time. We were established on the middle of the localizer for XXR inbound when an OAL I assume was supposed to be on XXL came over onto our course; and caused us to get an RA. We had to descend roughly 300-700 feet per the RA guidance to avoid the conflict.
EMB-175 Captain reported taking evasive action to avoid another aircraft while on approach to landing.