Narrative:

A B737 was on a vector to the base leg to turn a 10 mile final; and a C208 a law enforcement aircraft was on an active mission approximately 1-2 miles south of the final approach course and maneuvering at 5;500 ft MSL. Traffic was called to both airplanes more than once; however with other things going on; I failed to instruct either pilot to 'maintain visual separation'. The B737 was now on vectors to final and asked if they could square the turn to final and that he saw the VFR C208. I wasn't able to approve it because there was a heavy airbus on final and immediately after I informed the pilot I was unable to approve his request I canceled his approach clearance; issued a heading of 170 and issued an altitude of 5;500 ft because directly south of the aircraft was a 5;500 ft MVA. This transmission was not acknowledged and 'someone on the air said blocked'. I then went back a second time and issued to the B737 'approach clearance canceled; fly heading 170 and maintain 5;500'; however this transmission also went unanswered. I went back and a third time issued the same previous instructions to the B737 and at that point he advised me he is in a TCAS RA descent and was around 5;100; but turning left to a 170 heading. I told the pilot to advise when he was complete with his RA and could accept the maneuver. By this time the B737 was southeast bound and there was no longer a conflict. First; I would make sure to ensure visual separation was being applied to one or both of the airplanes. Second; I felt compelled to work the C208 and not move him because he was on an active law enforcement mission at that moment. I thought there was enough room in the area; but the C208 suddenly moved towards the point where I was vectoring too. In the future; I imagine we shouldn't be able to approve any kind of mission whether it is a law enforcement or a photo mission in such close proximity to a busy final. There are lots of photo mission and law enforcement missions approved that always come very close to final. I think these should be approved less and with more awareness on impact of the standard operation and its safety.

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Original NASA ASRS Text

Title: L30 Controller described a TCAS RA event involving a Law Enforcement aircraft and an Air Carrier arrival into LAS; the reporter expressing concern regarding the approval procedures for these types of operations.

Narrative: A B737 was on a vector to the base leg to turn a 10 mile final; and a C208 a Law Enforcement aircraft was on an active mission approximately 1-2 miles south of the final approach course and maneuvering at 5;500 FT MSL. Traffic was called to both airplanes more than once; however with other things going on; I failed to instruct either pilot to 'maintain visual separation'. The B737 was now on vectors to final and asked if they could square the turn to final and that he saw the VFR C208. I wasn't able to approve it because there was a heavy Airbus on final and immediately after I informed the pilot I was unable to approve his request I canceled his approach clearance; issued a heading of 170 and issued an altitude of 5;500 FT because directly south of the aircraft was a 5;500 FT MVA. This transmission was not acknowledged and 'someone on the air said blocked'. I then went back a second time and issued to the B737 'Approach clearance canceled; fly heading 170 and maintain 5;500'; however this transmission also went unanswered. I went back and a third time issued the same previous instructions to the B737 and at that point he advised me he is in a TCAS RA descent and was around 5;100; but turning left to a 170 heading. I told the pilot to advise when he was complete with his RA and could accept the maneuver. By this time the B737 was southeast bound and there was no longer a conflict. First; I would make sure to ensure visual separation was being applied to one or both of the airplanes. Second; I felt compelled to work the C208 and not move him because he was on an active Law Enforcement Mission at that moment. I thought there was enough room in the area; but the C208 suddenly moved towards the point where I was vectoring too. In the future; I imagine we shouldn't be able to approve any kind of mission whether it is a Law Enforcement or a photo mission in such close proximity to a busy final. There are lots of photo mission and Law Enforcement missions approved that always come very close to final. I think these should be approved less and with more awareness on impact of the standard operation and its safety.

Data retrieved from NASA's ASRS site as of July 2013 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.