Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 130; Flight Crew Total 2243; Flight Crew Type 2243
Confusion; Communication Breakdown; Situational Awareness
ATC Issue All Types; Conflict NMAC
Airspace Structure; Weather; Procedure; Human Factors
I DO NOT KNOW IF THIS WAS A CLOSE CALL. We never received an RA. We were on final to ZZZ Runway XXL. Weather was below CATIII mins. We were established on the LOC; I believe level at 3;000 feet or 4;000 feet. A white traffic symbol popped up showing 3 to 4 hundred feet. below us under the tip of the triangle for our own ship display. As it passed to our left; we broke out of the clouds and saw it was an air carrier crossing over to the ZZZ ILS XX. We never received an RA nor were we ever given any traffic calls from approach.
Air Carrier Captain reported an NMAC with another air carrier crossing underneath them on final approach. The reporter stated they did not receive a TCAS/RA or traffic advisory from ATC.