Phl controller described a TCAS RA event between an IFR air carrier and VFR traffic that resulted in...

Attributes
ACN	1023625
Time
Date	201207
Local Time Of Day	1201-1800
Place
Locale Reference	PHL.Airport
State Reference	PA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Regional Jet 200 ER/LR (CRJ200)
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Route In Use	Vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Cessna Stationair/Turbo Stationair 6
Operating Under FAR Part	Part 135
Flight Phase	Cruise
Flight Plan	VFR
Person 1
Function	Approach Departure
Qualification	Air Traffic Control Fully Certified
Person 2
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	ATC Issue All Types Deviation - Altitude Excursion From Assigned Altitude

Narrative:

A C206 was orbiting at 4;500; VFR; northeast of frose intersection. A CRJ2 was heading 110 at 5;000 ft; IFR. I turned the CRJ2 southeast bound for the downwind to runway 35. I called the cessna traffic and the CRJ2 responded by saying they were responding to an RA and climbing. I called the overhead traffic and the CRJ2 responded by saying they had the B767 in sight maintaining visual separation. I replied saying 'caution wake turbulence.' the CRJ2 was now clear of the C206 and I issued a descent to 4;000 ft. Calibration of the TCAS system needs to be the same as FAA ATC separation minima. Five hundred feet is standard separation between an IFR and VFR aircraft in class B; and then the TCAS equipment needs to be exactly the same. TCAS created something out of nothing. There is no reason for this to happen and it could be a lot worse than what happened today. Rumor has it that TCAS resolution is set at 650 feet which is 150 higher than our minimum separation for IFR/VFR aircraft.

Original NASA ASRS Text

Title: PHL Controller described a TCAS RA event between an IFR Air Carrier and VFR traffic that resulted in an additional conflict with other IFR traffic. The Controller recommended re-calibration of TCA to coincide with ATC separation.

Narrative: A C206 was orbiting at 4;500; VFR; NE of FROSE Intersection. A CRJ2 was heading 110 at 5;000 FT; IFR. I turned the CRJ2 southeast bound for the downwind to Runway 35. I called the Cessna traffic and the CRJ2 responded by saying they were responding to an RA and climbing. I called the overhead traffic and the CRJ2 responded by saying they had the B767 in sight maintaining visual separation. I replied saying 'caution wake turbulence.' The CRJ2 was now clear of the C206 and I issued a descent to 4;000 FT. Calibration of the TCAS system needs to be the same as FAA ATC separation minima. Five hundred feet is standard separation between an IFR and VFR aircraft in Class B; and then the TCAS equipment needs to be exactly the same. TCAS created something out of nothing. There is no reason for this to happen and it could be a lot worse than what happened today. Rumor has it that TCAS resolution is set at 650 feet which is 150 higher than our minimum separation for IFR/VFR aircraft.

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.

Phl controller described a TCAS RA event between an IFR air carrier and VFR traffic that resulted in an additional conflict with other IFR traffic. The controller recommended re-calibration of TCA to coincide with ATC separation.