An unknown VFR small aircraft has a near collision with a descending A320 over ldn, va.

Attributes
ACN	449947
Time
Date	199909
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : ldn.vortac
Altitude	msl bound lower : 9700 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : iad.tracon tower : iah.tower
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Route In Use	arrival star : jasen2
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Navigation In Use	other vortac
Flight Phase	cruise : level
Route In Use	enroute : direct
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 213 flight time total : 11000 flight time type : 2390
ASRS Report	449947
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : multi engine
Events
Anomaly	conflict : airborne critical non adherence : required legal separation
Independent Detector	aircraft equipment : tcas other flight crewa
Resolutory Action	flight crew : took evasive action
Miss Distance	horizontal : 3000 vertical : 200
Supplementary
Problem Areas	Airspace Structure Flight Crew Human Performance ATC Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While descending through 10000 ft on the jasen 2 arrival into iad, our TCASII alerted us to traffic converging from our left. This traffic was an unrpted VFR light aircraft at 9500 ft, also heading for the ldn VOR. The alert came in the way of a climb RA at 9700 ft. I immediately disconnected the autoplt, advanced the throttles, and began a climb. When we visually acquired the traffic, I leveled the aircraft at 10000 ft. We advised approach control of the TCASII RA climb and the traffic. We continued to a normal landing. The climb maneuver was smooth with no passenger comments. Thank you TCASII.

Original NASA ASRS Text

Title: AN UNKNOWN VFR SMA HAS A NEAR COLLISION WITH A DSNDING A320 OVER LDN, VA.

Narrative: WHILE DSNDING THROUGH 10000 FT ON THE JASEN 2 ARR INTO IAD, OUR TCASII ALERTED US TO TFC CONVERGING FROM OUR L. THIS TFC WAS AN UNRPTED VFR LIGHT ACFT AT 9500 FT, ALSO HDG FOR THE LDN VOR. THE ALERT CAME IN THE WAY OF A CLB RA AT 9700 FT. I IMMEDIATELY DISCONNECTED THE AUTOPLT, ADVANCED THE THROTTLES, AND BEGAN A CLB. WHEN WE VISUALLY ACQUIRED THE TFC, I LEVELED THE ACFT AT 10000 FT. WE ADVISED APCH CTL OF THE TCASII RA CLB AND THE TFC. WE CONTINUED TO A NORMAL LNDG. THE CLB MANEUVER WAS SMOOTH WITH NO PAX COMMENTS. THANK YOU TCASII.

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.