CL65 flight crew reported taking evasive action to avoid a collision with a light aircraft on arriva...

Attributes
ACN	1461993
Time
Date	201707
Local Time Of Day	0601-1200
Place
Locale Reference	PHL.Airport
State Reference	PA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Regional Jet CL65 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Aircraft Low Wing 1 Eng Fixed Gear
Person 1
Function	Pilot Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Conflict Airborne Conflict Deviation - Track / Heading All Types

Narrative:

Descending to 9;000 feet on the BUNTS3 arrival into phl a target appeared on our mfd with no corresponding altitude. We began to look for the traffic and then received a TA alert from the TCAS and then spotted the target at our 12'oclock position within 3 miles. I then turned off the autopilot and turned at about 30-35 degrees bank to avoid colliding with the aircraft. The captain called ATC and advised them we were maneuvering to avoid colliding with the traffic. After we were clear of the traffic we requested to direct bunts to return to the arrival. After we returned to course we asked ATC about the traffic and they said they didn't have a mode C transponder and didn't think they were above 3;000 feet.always be vigilant for traffic regardless if ATC advises you of them or not. Be especially vigilant if the traffic target does not have an altitude shown.

Original NASA ASRS Text

Title: CL65 flight crew reported taking evasive action to avoid a collision with a light aircraft on arrival into PHL. Reporter stated the conflict aircraft had no altitude readout on the TCAS.

Narrative: Descending to 9;000 feet on the BUNTS3 Arrival into PHL a target appeared on our MFD with no corresponding altitude. We began to look for the traffic and then received a TA alert from the TCAS and then spotted the target at our 12'oclock position within 3 miles. I then turned off the autopilot and turned at about 30-35 degrees bank to avoid colliding with the aircraft. The Captain called ATC and advised them we were maneuvering to avoid colliding with the traffic. After we were clear of the traffic we requested to direct BUNTS to return to the arrival. After we returned to course we asked ATC about the traffic and they said they didn't have a Mode C transponder and didn't think they were above 3;000 feet.Always be vigilant for traffic regardless if ATC advises you of them or not. Be especially vigilant if the traffic target does not have an altitude shown.

Data retrieved from NASA's ASRS site 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.

CL65 flight crew reported taking evasive action to avoid a collision with a light aircraft on arrival into phl. Reporter stated the conflict aircraft had no altitude readout on the TCAS.