Mia controller described a TCAS RA event between an IFR and VFR aircraft6 separated by the required ...

Narrative:

A B737 while descending to 4;000 ft assigned by me; the radar controller; and on the fisel RNAV arrival; informed me that he was responding to an RA on a C182 who was directly below him VFR at 3;500 ft. The B737 only climbed up about 300 ft and did not conflict with any other traffic in the vicinity and then returned to 4;000 ft once clear of the conflict. Both the B737 and the C182 were informed well ahead of time about each other as traffic advisories and standard; class C vertical separation was applied and maintained the whole time (500 ft vertical IFR to VFR). [This is] yet another case of; more than likely; too sensitive of TCAS equipment on various types of airplanes/airlines. I had numerous other airliners fly over this cessna with the standard 500 ft vertical separation and no one else complained about traffic proximity nor responded to an RA. It seems like certain TCAS equipment just responds differently in various situations (maybe interpreting climb/descent rate too radically into the avoidance logic?).

Original NASA ASRS Text

Title: MIA Controller described a TCAS RA event between an IFR and VFR aircraft6 separated by the required standard; the reporter questioning the TCAS logic.

Narrative: A B737 while descending to 4;000 FT assigned by me; the Radar Controller; and on the FISEL RNAV arrival; informed me that he was responding to an RA on a C182 who was directly below him VFR at 3;500 FT. The B737 only climbed up about 300 FT and did not conflict with any other traffic in the vicinity and then returned to 4;000 FT once clear of the conflict. Both the B737 and the C182 were informed well ahead of time about each other as traffic advisories and standard; Class C vertical separation was applied and maintained the whole time (500 FT vertical IFR to VFR). [This is] yet another case of; more than likely; too sensitive of TCAS equipment on various types of airplanes/airlines. I had numerous other airliners fly over this Cessna with the standard 500 FT vertical separation and no one else complained about traffic proximity nor responded to an RA. It seems like certain TCAS equipment just responds differently in various situations (maybe interpreting climb/descent rate too radically into the avoidance logic?).

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	982168
Time
Date	201112
Local Time Of Day	1801-2400
Place
Locale Reference	FLL.Airport
State Reference	FL
Aircraft 1
Make Model Name	Skylane 182/RG Turbo Skylane/RG
Flight Phase	Cruise
Flight Plan	VFR
Aircraft 2
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Person 1
Function	Approach
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Aircraft Equipment Problem Less Severe Conflict Airborne Conflict

Mia controller described a TCAS RA event between an IFR and VFR aircraft6 separated by the required standard; the reporter questioning the TCAS logic.