Pbi controller described a conflict event during the application of visual separation between an IFR...

Narrative:

I was working all pbi airspace combined. I was handed off air carrier X from the center descending VFR out of 13;500 ft. Aircraft Y was enroute to vrb at 7;000 ft. Air carrier X was issued traffic on some VFR PA28's then on aircraft Y. Aircraft Y was issued traffic on air carrier X; reported him in sight; and was told to maintain visual separation. Air carrier X eventually got aircraft Y in sight and; since he was VFR; he was not issued any control instructions. Air carrier X continued descending directly at aircraft Y and the pilot questioned air carrier X's intentions. Air carrier X appeared to pass directly over aircraft Y with 300 ft vertical separation. The pilot of aircraft Y said his passengers were unhappy with the close proximity of air carrier X; but he never reported a near mid-air. Recommendation; since the closure rate of the aircraft was near 500 KTS I considered air carrier X's actions unsafe. Both aircraft did have one another insight; but air carrier X's continued descent did not seem appropriate for the aircraft. Both aircraft are larger turboprops and I don't know if they need to keep a minimum safe distance when VFR. I could have stopped air carrier X's descent above aircraft Y; but they had one another insight and I didn't want to restrict an aircraft's ability to maintain VFR. If I knew of the aircraft's intentions to practically buzz the other I would have stopped his descent.

Original NASA ASRS Text

Title: PBI Controller described a conflict event during the application of visual separation between an IFR and VFR traffic; the reporter noting positive altitude separation may have more appropriate until the aircraft passed.

Narrative: I was working all PBI airspace combined. I was handed off Air Carrier X from the Center descending VFR out of 13;500 FT. Aircraft Y was enroute to VRB at 7;000 FT. Air Carrier X was issued traffic on some VFR PA28's then on Aircraft Y. Aircraft Y was issued traffic on Air Carrier X; reported him in sight; and was told to maintain visual separation. Air Carrier X eventually got Aircraft Y in sight and; since he was VFR; he was not issued any control instructions. Air Carrier X continued descending directly at Aircraft Y and the pilot questioned Air Carrier X's intentions. Air Carrier X appeared to pass directly over Aircraft Y with 300 FT vertical separation. The pilot of Aircraft Y said his passengers were unhappy with the close proximity of Air Carrier X; but he never reported a near mid-air. Recommendation; since the closure rate of the aircraft was near 500 KTS I considered Air Carrier X's actions unsafe. Both aircraft did have one another insight; but Air Carrier X's continued descent did not seem appropriate for the aircraft. Both aircraft are larger turboprops and I don't know if they need to keep a minimum safe distance when VFR. I could have stopped Air Carrier X's descent above Aircraft Y; but they had one another insight and I didn't want to restrict an aircraft's ability to maintain VFR. If I knew of the aircraft's intentions to practically buzz the other I would have stopped his descent.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	934773
Time
Date	201102
Local Time Of Day	0001-0600
Place
Locale Reference	PBI.Airport
State Reference	FL
Environment
Light	Night
Aircraft 1
Make Model Name	Saab 340 Undifferentiated
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Route In Use	Vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Super King Air 200
Flight Phase	Descent
Route In Use	None
Flight Plan	VFR
Person 1
Function	Departure Approach
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	Conflict NMAC

Pbi controller described a conflict event during the application of visual separation between an IFR and VFR traffic; the reporter noting positive altitude separation may have more appropriate until the aircraft passed.