Narrative:

First time worked in the temporary tower. Winds were out of the south up to 10 knots; and we were beginning to setup for a runway change. A VFR requested a right downwind departure but was given a left downwind departure due to an arrival aircraft from the east and aircraft in the pattern on the right runway. When the VFR was downwind abeam the numbers they were given a right turn twenty degrees to pass behind aircraft X on base. Aircraft X was given traffic on base to final for the parallel but not the downwind traffic that was passing behind and received a TCAS RA on the VFR. When aircraft X advised they were responding to an RA I instructed them to make left traffic pattern altitude 2;000 feet. The aircraft was about 2.5 miles south of an adjacent airport runway centerline and about a 1/2 mile north of any conflicting traffic.there was another aircraft that I had to focus extra attention on because they came in VFR and were at 5;500 feet 6 miles northwest of this airport were issued left traffic pattern altitude 2;000 feet. Aircraft Y was an IFR aircraft about a 1/2 mile west of the airport on approach to the adjacent airport and aircraft X was about a 1/2 south of aircraft Y's approach course centerline when the conflict alert alarm activated during a transmission to another aircraft. As soon as it went off I stopped that transmission and told aircraft X that I need him down at 2;000 feet now. I did not issue aircraft X traffic to aircraft Y because I saw the two aircraft and aircraft X was descending. I determined that they were not going to hit and moved on. I was just trying to keep up with the current traffic level and was scrambling to keep everyone safe. I was overworked for the session on a position that I had not worked yet in the temporary tower with combined positions and no assist due to configuration of the cab; the layout; and staffing. We are to assume that the ILS approach into the adjacent airport is always in use regardless of actual traffic. Traffic should be pointed out to us to make us aware of the potential traffic conflict; because TRACON does not stagger the arrivals into my airport and the adjacent airport. When an aircraft does a go-around not associated with an RA this isn't as much of a problem. However; when there is a go-around associated with an RA the pilot complies with the instructions of the RA. I did not anticipate aircraft X to continue to climb for two miles after the conflict and that they were going to descend to the pattern altitude that was issued. The temporary tower does not have a single position that is setup for a north configuration. All the positions face to the north adding to the complexity. We also do not have visibility to the west on the downwind due to the location of the temporary tower sitting below the tower being remodeled.

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Original NASA ASRS Text

Title: VNY Tower Controller reported an aircraft on final approach responded to an RA and climbed into confliction with an aircraft on approach to an adjacent airport.

Narrative: First time worked in the temporary tower. Winds were out of the south up to 10 knots; and we were beginning to setup for a runway change. A VFR requested a right downwind departure but was given a left downwind departure due to an arrival aircraft from the east and aircraft in the pattern on the right runway. When the VFR was downwind abeam the numbers they were given a right turn twenty degrees to pass behind Aircraft X on base. Aircraft X was given traffic on base to final for the parallel but not the downwind traffic that was passing behind and received a TCAS RA on the VFR. When Aircraft X advised they were responding to an RA I instructed them to make left traffic pattern altitude 2;000 feet. The aircraft was about 2.5 miles south of an adjacent airport runway centerline and about a 1/2 mile north of any conflicting traffic.There was another aircraft that I had to focus extra attention on because they came in VFR and were at 5;500 feet 6 miles northwest of this airport were issued left traffic pattern altitude 2;000 feet. Aircraft Y was an IFR aircraft about a 1/2 mile west of the airport on approach to the adjacent airport and Aircraft X was about a 1/2 south of Aircraft Y's approach course centerline when the Conflict Alert Alarm activated during a transmission to another aircraft. As soon as it went off I stopped that transmission and told Aircraft X that I need him down at 2;000 feet NOW. I did not issue Aircraft X traffic to Aircraft Y because I saw the two aircraft and Aircraft X was descending. I determined that they were not going to hit and moved on. I was just trying to keep up with the current traffic level and was scrambling to keep everyone safe. I was overworked for the session on a position that I had not worked yet in the temporary tower with combined positions and no assist due to configuration of the cab; the layout; and staffing. We are to assume that the ILS Approach into the adjacent airport is always in use regardless of actual traffic. Traffic should be pointed out to us to make us aware of the potential traffic conflict; because TRACON does not stagger the arrivals into my airport and the adjacent airport. When an aircraft does a go-around not associated with an RA this isn't as much of a problem. However; when there is a go-around associated with an RA the pilot complies with the instructions of the RA. I did not anticipate Aircraft X to continue to climb for two miles after the conflict and that they were going to descend to the pattern altitude that was issued. The temporary tower does not have a single position that is setup for a north configuration. All the positions face to the north adding to the complexity. We also do not have visibility to the west on the downwind due to the location of the temporary tower sitting below the tower being remodeled.

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.