B737NG first officer reported a near midair collision with a warbird while on final approach.

Attributes
ACN	1610077
Time
Date	201901
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	IMC
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Flight Plan	IFR
Aircraft 2
Make Model Name	Military
Person 1
Function	Pilot Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 3 Flight Crew Total 14000 Flight Crew Type 1500
Events
Anomaly	Conflict NMAC Deviation - Procedural Published Material / Policy
Miss Distance	Vertical 500

Narrative:

We were on the RNAV (rnp) runway 31 approach with clearance for that approach when a [warbird] came barreling up in front of us. I saw it on the TCAS turn from white to amber; and then red. At the time; we were IFR; just about to break out into VMC conditions. A minute or two earlier the tower reported a [warbird] flying in the area; and we got the impression that the controller personally knew the pilot of the [warbird]. We were on the approach; exactly where we were supposed to be; when the RA happened. I executed a climbing RA (per guidance); and within maybe 40 seconds we got a 'clear of conflict' and were able to continue the approach to an uneventful landing. I never saw the plane; but I have no doubt that it our clearance was not very far apart - probably less than 500 feet. We reported the incident to the tower; and they in turn said they would report it through their channels.the [warbird] pilot needs to understand that you cannot fly into the approach end of a runway; especially in marginal to IMC conditions.

Original NASA ASRS Text

Title: B737NG First Officer reported a NMAC with a warbird while on final approach.

Narrative: We were on the RNAV (RNP) Runway 31 approach with clearance for that approach when a [warbird] came barreling up in front of us. I saw it on the TCAS turn from white to amber; and then red. At the time; we were IFR; just about to break out into VMC conditions. A minute or two earlier the Tower reported a [warbird] flying in the area; and we got the impression that the Controller personally knew the pilot of the [warbird]. We were on the approach; exactly where we were supposed to be; when the RA happened. I executed a climbing RA (per guidance); and within maybe 40 seconds we got a 'clear of conflict' and were able to continue the approach to an uneventful landing. I never saw the plane; but I have no doubt that it our clearance was not very far apart - probably less than 500 feet. We reported the incident to the Tower; and they in turn said they would report it through their channels.The [warbird] pilot needs to understand that you cannot fly into the approach end of a runway; especially in marginal to IMC conditions.

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.