Narrative:

I was working local 1. There were two GA aircraft on final for runway 31L that were cleared to land. I had one GA aircraft extended on right downwind to follow the two aircraft on final; but then I received an inbound point-out from P80; the overlying TRACON; on aircraft X from the southeast. I asked P80 to slow aircraft X and direct him to fly over the fix intll. I told the GA aircraft extended in the right downwind that I was unable to accommodate his full stop on runway 31L because of the faster aircraft X traffic. I instructed the GA aircraft to extend right downwind and contact the local 2 controller on 132.8 for a full stop landing on runway 31R. Aircraft X checked on frequency and I cleared him to land number two behind the GA aircraft on short final. Additionally; I told aircraft X that there would be traffic ahead and to his right on extended final for the north parallel. When aircraft X was on about a five mile final; I observed an aircraft on what appeared to be a right base about four miles from the airport. I told aircraft X to stop his descent and that it appeared that the aircraft for the north runway was overshooting final underneath aircraft X at 1000 MSL. At that point aircraft X indicated 1600 MSL. Aircraft X said that he saw the aircraft and was responding to a TCAS RA; but it didn't look like one of the high wing GA aircraft. Local 2 immediately advised that that was not his aircraft; and we determined that the southwest-bound aircraft was an airspace violator. I passed this information along to aircraft X and asked if he would like to continue the approach. Aircraft X said he could; and I cleared him to land again on runway 31L. I did not observe aircraft X take any evasive maneuver to avoid the aircraft. I had both aircraft in sight the entire time; and aircraft X appeared to cross over the violator between 400-600 feet. After aircraft X landed the pilot called the tower and advised that the violator in question; aircraft Y; landed at 7s3 shortly after. The pilot of aircraft X also advised that they were reporting this incident as a near mid-air collision.on the falcon replay; aircraft Y could be seen violating the airspace from the northeast and then exiting the delta airspace and skirt the edge of the airspace south bound. Aircraft Y re-entered the airspace from the southeast and made a turn southwest bound. This put him directly under final at about 1000 MSL. Had I noticed this violator earlier; I could have prepped aircraft X sooner. But I am confident that my timely actions to stop aircraft X's descent prevented this from becoming a collision.

Google
 

Original NASA ASRS Text

Title: HIO Tower Controller and pilot reported of a Class Delta airspace violation and a NMAC.

Narrative: I was working Local 1. There were two GA aircraft on final for Runway 31L that were cleared to land. I had one GA aircraft extended on right downwind to follow the two aircraft on final; but then I received an inbound point-out from P80; the overlying TRACON; on Aircraft X from the southeast. I asked P80 to slow Aircraft X and direct him to fly over the fix INTLL. I told the GA aircraft extended in the right downwind that I was unable to accommodate his full stop on Runway 31L because of the faster Aircraft X traffic. I instructed the GA aircraft to extend right downwind and contact the Local 2 controller on 132.8 for a full stop landing on Runway 31R. Aircraft X checked on frequency and I cleared him to land number two behind the GA aircraft on short final. Additionally; I told Aircraft X that there would be traffic ahead and to his right on extended final for the north parallel. When Aircraft X was on about a five mile final; I observed an aircraft on what appeared to be a right base about four miles from the airport. I told Aircraft X to stop his descent and that it appeared that the aircraft for the north runway was overshooting final underneath Aircraft X at 1000 MSL. At that point Aircraft X indicated 1600 MSL. Aircraft X said that he saw the aircraft and was responding to a TCAS RA; but it didn't look like one of the high wing GA aircraft. Local 2 immediately advised that that was not his aircraft; and we determined that the southwest-bound aircraft was an airspace violator. I passed this information along to Aircraft X and asked if he would like to continue the approach. Aircraft X said he could; and I cleared him to land again on Runway 31L. I did not observe Aircraft X take any evasive maneuver to avoid the aircraft. I had both aircraft in sight the entire time; and Aircraft X appeared to cross over the violator between 400-600 feet. After Aircraft X landed the pilot called the tower and advised that the violator in question; Aircraft Y; landed at 7S3 shortly after. The pilot of Aircraft X also advised that they were reporting this incident as a near mid-air collision.On the FALCON replay; Aircraft Y could be seen violating the airspace from the northeast and then exiting the Delta airspace and skirt the edge of the airspace south bound. Aircraft Y re-entered the airspace from the southeast and made a turn southwest bound. This put him directly under final at about 1000 MSL. Had I noticed this violator earlier; I could have prepped Aircraft X sooner. But I am confident that my timely actions to stop Aircraft X's descent prevented this from becoming a collision.

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.