Altitude deviation altitude excursion in flight crew response to TCASII RA in TCA on VFR traffic.

Attributes
ACN	249562
Time
Date	199308
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : phl
State Reference	PA
Altitude	msl bound lower : 5800 msl bound upper : 6000
Environment
Flight Conditions	Marginal
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : phl tower : cdw
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport
Navigation In Use	Other Other
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : cfi pilot : atp
Experience	flight time last 90 days : 150 flight time total : 8200 flight time type : 750
ASRS Report	249562
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : flight engineer pilot : instrument pilot : atp pilot : commercial
Experience	flight time last 90 days : 150 flight time total : 6000 flight time type : 300
ASRS Report	249783
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 0 vertical : 500
Supplementary
Air Traffic Incident	Pilot Deviation
Situations
ATC Facility	procedure or policy : unspecified

Narrative:

The aircraft we were flying, an medium large transport, was level at 6000 ft being vectored by phl approach. The approach controller advised us of VFR traffic at 6500 ft in our proximity. Our TCASII system tracked the other aircraft giving us first a TA and then an RA. The first officer (PF) responded to the RA by descending approximately 200 ft below our assigned altitude. The controller was advised of the situation and asked us to return to 6000 ft when clear of the conflict. I believe 2 primary factors caused this situation. I question the judgement of the other PIC in operating his aircraft in at best marginal VFR in a TCA. I question the judgement of the controller to allow both aircraft, which she had control of, to pass within 500 ft of each other while neither had visual contact.

Original NASA ASRS Text

Title: ALTDEV ALT EXCURSION IN FLC RESPONSE TO TCASII RA IN TCA ON VFR TFC.

Narrative: THE ACFT WE WERE FLYING, AN MLG, WAS LEVEL AT 6000 FT BEING VECTORED BY PHL APCH. THE APCH CTLR ADVISED US OF VFR TFC AT 6500 FT IN OUR PROX. OUR TCASII SYS TRACKED THE OTHER ACFT GIVING US FIRST A TA AND THEN AN RA. THE FO (PF) RESPONDED TO THE RA BY DSNDING APPROX 200 FT BELOW OUR ASSIGNED ALT. THE CTLR WAS ADVISED OF THE SIT AND ASKED US TO RETURN TO 6000 FT WHEN CLR OF THE CONFLICT. I BELIEVE 2 PRIMARY FACTORS CAUSED THIS SIT. I QUESTION THE JUDGEMENT OF THE OTHER PIC IN OPERATING HIS ACFT IN AT BEST MARGINAL VFR IN A TCA. I QUESTION THE JUDGEMENT OF THE CTLR TO ALLOW BOTH ACFT, WHICH SHE HAD CTL OF, TO PASS WITHIN 500 FT OF EACH OTHER WHILE NEITHER HAD VISUAL CONTACT.

Data retrieved from NASA's ASRS site as of July 2007 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.