Narrative:

A C207; had departed merrill field airport (mri) behind a company C207; both were VFR westbound heading across knik arm for the west side of cook inlet to either the villages of beluga or tyonek. An A319; was inbound to anchorage intl. Airport (anc) from the north; landing runway 15. A runway change from a runway 7/33 flow to a runway 15/25 flow had just taken place at anc. I had sat down at the north low position which was right after the runway change had occurred. The two C207s both climbed high over the city before crossing knik arm due to an aircraft on an instrument approach landing runway 6 at elemendorf air force base (edf) which is adjacent to merrill field. VFR aircraft arriving and departing mri from the northwest must cross knik arm at or below 006; or at or above 020 when there are aircraft arriving straight in to runway 6 at edf to comply with far part 93. Both C207 aircraft opted to go high across the inlet rather than low. They proceeded west northwest bound towards the pt. Mckenzie area which is a very congested area for VFR aircraft and which is near the 15 final approach course. There were other VFR aircraft in the mri area initially where the two C207s were; and there were multiple ca alarms going off and data tags covering each other and changing positions. I was initially distracted with all of that and with other aircraft as I was getting settled into the position including a helicopter that wasn't familiar with a VFR arrival route into anc from the north with runway 15 in use. After crossing the inlet; one of the C207s advised that he wanted to descend to 015 from 022. I then noticed his proximity to the A319 who was on final to runway 15; and who had already been changed over to anchorage tower frequency from final. I gave the C207 traffic at his 1 o'clock and 2 miles. The C207 initially did not see the A319. I did not approve the C207's descent as I was expecting the A319 to continue his descent assuming that he was on the ILS to 15 (as that was the approach that was being advertised). If I would approved the C207's request for descent; it would have put them on a converging course with the A319. I again issued traffic to the C207 who advised that he had that he had the A319 in sight. I advised the C207 to maintain visual separation from the A319. I then noted the A319 descend out of 022 to 020 as the C207 passed from the A319's 12 to 1 o'clock at 022 and approximately 1 mile ahead. I felt that the A319 was higher than he should have been on an ILS to 15 at that point which was approximately 5.5 - 5.75 miles out on the localizer. He may have been cleared for a visual approach; but I'm not sure. In speaking with my supervisor afterwards; he advised that the A319 may have had a TCAS/RA; but did not act on it; as he was descending on the approach; but wasn't sure. Additionally; weather in the area was VMC; but there were scattered/broken layers north of pt. Mckenzie in the area of the 15 final approach course which made it difficult for the C207 to see the A319. Given a similar situation with similar circumstances; I feel that all aircraft coming out of mri wanting to cross the inlet to go westbound at higher altitudes need to be advised to fly north and east of the runway 15 final approach course after crossing the inlet until they can descend to a lower altitude to cross under the final approach course. I also feel that aircraft landing runway 15 at anc need to be instructed to cross abeam pt. Mckenzie at 016 if on a visual approach.

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Original NASA ASRS Text

Title: A11 Controller described a conflict event involving IFR and VFR traffic complicated by local procedures and airport locations.

Narrative: A C207; had departed Merrill Field Airport (MRI) behind a company C207; both were VFR westbound heading across Knik Arm for the west side of Cook Inlet to either the villages of Beluga or Tyonek. An A319; was inbound to Anchorage Intl. Airport (ANC) from the north; landing Runway 15. A runway change from a Runway 7/33 flow to a Runway 15/25 flow had just taken place at ANC. I had sat down at the North Low position which was right after the runway change had occurred. The two C207s both climbed high over the city before crossing Knik Arm due to an aircraft on an instrument approach landing Runway 6 at Elemendorf Air Force Base (EDF) which is adjacent to Merrill Field. VFR aircraft arriving and departing MRI from the northwest must cross Knik Arm at or below 006; or at or above 020 when there are aircraft arriving straight in to Runway 6 at EDF to comply with FAR Part 93. Both C207 aircraft opted to go high across the inlet rather than low. They proceeded west northwest bound towards the Pt. McKenzie area which is a very congested area for VFR aircraft and which is near the 15 final approach course. There were other VFR aircraft in the MRI area initially where the two C207s were; and there were multiple CA alarms going off and data tags covering each other and changing positions. I was initially distracted with all of that and with other aircraft as I was getting settled into the position including a helicopter that wasn't familiar with a VFR arrival route into ANC from the north with Runway 15 in use. After crossing the inlet; one of the C207s advised that he wanted to descend to 015 from 022. I then noticed his proximity to the A319 who was on final to Runway 15; and who had already been changed over to Anchorage Tower frequency from Final. I gave the C207 traffic at his 1 o'clock and 2 miles. The C207 initially did not see the A319. I did not approve the C207's descent as I was expecting the A319 to continue his descent assuming that he was on the ILS to 15 (as that was the approach that was being advertised). If I would approved the C207's request for descent; it would have put them on a converging course with the A319. I again issued traffic to the C207 who advised that he had that he had the A319 in sight. I advised the C207 to maintain visual separation from the A319. I then noted the A319 descend out of 022 to 020 as the C207 passed from the A319's 12 to 1 o'clock at 022 and approximately 1 mile ahead. I felt that the A319 was higher than he should have been on an ILS to 15 at that point which was approximately 5.5 - 5.75 miles out on the localizer. He may have been cleared for a visual approach; but I'm not sure. In speaking with my Supervisor afterwards; he advised that the A319 may have had a TCAS/RA; but did not act on it; as he was descending on the approach; but wasn't sure. Additionally; weather in the area was VMC; but there were scattered/broken layers north of Pt. McKenzie in the area of the 15 final approach course which made it difficult for the C207 to see the A319. Given a similar situation with similar circumstances; I feel that all aircraft coming out of MRI wanting to cross the inlet to go westbound at higher altitudes need to be advised to fly north and east of the Runway 15 final approach course after crossing the inlet until they can descend to a lower altitude to cross under the final approach course. I also feel that aircraft landing Runway 15 at ANC need to be instructed to cross abeam Pt. McKenzie at 016 if on a visual approach.

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.