Narrative:

Aircraft Y; on final to runway 19C; had a TCAS RA with aircraft X; crossing the final while en-route to jyo. There was no loss of separation as aircraft X was maintaining visual separation from aircraft Y. It was also entered in cedar as our monthly class B services ssr; currently in draft status but already reviewed by our local safety council. Iad was VMC; arriving 19L/C/right; departing runway 30. Local control (local control)1 radar identified aircraft X east of iad and approved his request to proceed to jyo via helicopter routes 20 and 9. Another helicopter; aircraft Z; was on helicopter route 9 southeast bound and was switched to LC1 by potomac approach. There was no requirement to separate the two helicopters which would have been opposite direction on route 9; however; LC1 decided to clear aircraft X direct jyo to avoid the conflict. LC1 pointed out aircraft X to LC3 who was concerned with aircraft Z; not on LC3's frequency. LC1 was talking to aircraft Z and advised that aircraft X would cross the 19C final. The point-out was approved with no mention of aircraft Y descending on 19C final; about 6 miles from aircraft X. Both aircraft appeared to be on intercept courses. Since most aircraft on a visual approach use the glideslope for guidance; this would put aircraft X crossing [runway] 19C at about the same altitude that aircraft Y would be as he descended on the visual approach in the vicinity of the final approach fix. LC1 eventually pointed out aircraft Y to aircraft X who said he would maintain visual separation from the aircraft. The frequency was congested at the time; but LC1 must have heard aircraft X's call sign or just assumed it was him. LC1 said approved. The aircraft were still converging; with about 2 miles separation. LC3 called the helicopter traffic to aircraft Y but really didn't know what the helicopter would do; only that it would maintain visual separation from aircraft Y. Aircraft X; on his own; turned north to avoid aircraft Y as LC1 told him to descend to 1;000 ft. As the two targets approached one another; aircraft Y advised LC3 that he had a TCAS RA. I suspect the conflict alert sounded but that data was not available for this analysis.a better way of handling this would have been for LC1 to keep aircraft X on helicopter route 9 (which by design caps the helicopters at 700 ft between dranesville and xerox; well underneath the glideslope) and just advise him of aircraft Z. Or; once clear of aircraft Z; LC1 could have turned aircraft X north to rejoin route 9 and pass behind aircraft Y; providing a wider margin of separation and alleviating confusion. With proper coordination; LC3 could have advised aircraft Y of ATC's intentions for aircraft X. Instead; at this crucial point in the arrival phase; the separation was left up to aircraft X. This lack of positive control by ATC resulted in a TCAS RA on 4-mile final and was a safety risk. Unfortunately; this facility has had a long history of these types of situations; crossing the finals with VFR aircraft and not providing positive control resulting in many TCAS RA's. For the last four years we have tried to educate our controllers by providing refresher training during which videos were shown of similar scenarios. We had meetings with the chief pilot of the medi-vac unit. We redesigned the helicopter routes to provide more vertical separation underneath our finals. Yet these two local controllers; who had that training; still turned the separation over to the helicopter crew. Issuing vectors to provide positive control is second nature to radar controllers. This particular LC1 controller does not have rtf type radar training. LC3; an experienced tower controller; has en-route radar training but was unsuccessful at the center. No manually written flight progress strips were found for the two helicopters. These strips serve as memory joggers and are required by SOP. This is a systemic issue at our facility. 1) ipm with individual local controllers.2) a discussion with chief pilot about the scenario. We did this once before with some success; but maybe they need to be reminded that coming in such close proximity to aircraft causes TCAS RA's compromising safety.3) rtf type training for controllers at towers with class B airspace.

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Original NASA ASRS Text

Title: IAD Staff Specialists reports of an incident that involved two arrival aircraft and a TCAS RA caused by a helicopter crossing the arrival paths. Memory jogger was not used by the local Controller to show the helicopter involved.

Narrative: Aircraft Y; on final to Runway 19C; had a TCAS RA with Aircraft X; crossing the final while en-route to JYO. There was no loss of separation as Aircraft X was maintaining visual separation from Aircraft Y. It was also entered in CEDAR as our monthly Class B services SSR; currently in draft status but already reviewed by our Local Safety Council. IAD was VMC; arriving 19L/C/R; Departing Runway 30. Local Control (LC)1 radar identified Aircraft X east of IAD and approved his request to proceed to JYO via Helicopter Routes 20 and 9. Another helicopter; Aircraft Z; was on Helicopter Route 9 southeast bound and was switched to LC1 by Potomac Approach. There was no requirement to separate the two helicopters which would have been opposite direction on Route 9; however; LC1 decided to clear Aircraft X direct JYO to avoid the conflict. LC1 pointed out Aircraft X to LC3 who was concerned with Aircraft Z; not on LC3's frequency. LC1 was talking to Aircraft Z and advised that Aircraft X would cross the 19C final. The point-out was approved with no mention of Aircraft Y descending on 19C final; about 6 miles from Aircraft X. Both aircraft appeared to be on intercept courses. Since most aircraft on a visual approach use the glideslope for guidance; this would put Aircraft X crossing [Runway] 19C at about the same altitude that Aircraft Y would be as he descended on the visual approach in the vicinity of the final approach fix. LC1 eventually pointed out Aircraft Y to Aircraft X who said he would maintain visual separation from the aircraft. The frequency was congested at the time; but LC1 must have heard Aircraft X's call sign or just assumed it was him. LC1 said approved. The aircraft were still converging; with about 2 miles separation. LC3 called the helicopter traffic to Aircraft Y but really didn't know what the helicopter would do; only that it would maintain visual separation from Aircraft Y. Aircraft X; on his own; turned north to avoid Aircraft Y as LC1 told him to descend to 1;000 FT. As the two targets approached one another; Aircraft Y advised LC3 that he had a TCAS RA. I suspect the conflict alert sounded but that data was not available for this analysis.A better way of handling this would have been for LC1 to keep Aircraft X on Helicopter Route 9 (which by design caps the helicopters at 700 FT between DRANESVILLE and XEROX; well underneath the glideslope) and just advise him of Aircraft Z. Or; once clear of Aircraft Z; LC1 could have turned Aircraft X north to rejoin Route 9 and pass behind Aircraft Y; providing a wider margin of separation and alleviating confusion. With proper coordination; LC3 could have advised Aircraft Y of ATC's intentions for Aircraft X. Instead; at this crucial point in the arrival phase; the separation was left up to Aircraft X. This lack of positive control by ATC resulted in a TCAS RA on 4-mile final and was a safety risk. Unfortunately; this facility has had a long history of these types of situations; crossing the finals with VFR aircraft and not providing positive control resulting in many TCAS RA's. For the last four years we have tried to educate our controllers by providing refresher training during which videos were shown of similar scenarios. We had meetings with the chief pilot of the medi-vac unit. We redesigned the helicopter routes to provide more vertical separation underneath our finals. Yet these two local controllers; who had that training; still turned the separation over to the helicopter crew. Issuing vectors to provide positive control is second nature to radar controllers. This particular LC1 controller does not have RTF type radar training. LC3; an experienced Tower controller; has en-route radar training but was unsuccessful at the Center. No manually written flight progress strips were found for the two helicopters. These strips serve as memory joggers and are required by SOP. This is a systemic issue at our facility. 1) IPM with individual local controllers.2) A discussion with Chief Pilot about the scenario. We did this once before with some success; but maybe they need to be reminded that coming in such close proximity to aircraft causes TCAS RA's compromising safety.3) RTF type training for controllers at Towers with Class B airspace.

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.