Aircraft reported coming in close proximity to another aircraft and reported a near midair collision...

Attributes
ACN	127055
Time
Date	198910
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : bwi
State Reference	MD
Altitude	msl bound lower : 6000 msl bound upper : 8000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
Flight Phase	descent other
Route In Use	arrival other enroute airway : bwi
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	cruise other
Flight Plan	None
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller radar : 5
ASRS Report	127055
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : nmac non adherence : far other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	Other
Miss Distance	horizontal : 0 vertical : 400
Supplementary
Primary Problem	Flight Crew Human Performance

Narrative:

Air carrier X reported near miss with a VFR small transport. Callback conversation with reporter revealed the following: the reporter doesn't remember too much about the incident, although he does remember working the position combined with no training in progress. The aircraft he was working was either an overflt to dca, or an arrival to bwi. The aircraft reported that he had a near midair collision with a twin-engine aircraft. The reporter told his supervisor, but did not ask the aircraft for more information. No distance between aircraft was given. The other aircraft was not being worked by ATC and not observed on radar. No traffic was issued. He said his aircraft was an small transport.

Original NASA ASRS Text

Title: ACFT REPORTED COMING IN CLOSE PROX TO ANOTHER ACFT AND REPORTED A NMAC.

Narrative: ACR X RPTED NEAR MISS WITH A VFR SMT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: THE RPTR DOESN'T REMEMBER TOO MUCH ABOUT THE INCIDENT, ALTHOUGH HE DOES REMEMBER WORKING THE POS COMBINED WITH NO TRNING IN PROGRESS. THE ACFT HE WAS WORKING WAS EITHER AN OVERFLT TO DCA, OR AN ARR TO BWI. THE ACFT RPTED THAT HE HAD A NMAC WITH A TWIN-ENG ACFT. THE RPTR TOLD HIS SUPVR, BUT DID NOT ASK THE ACFT FOR MORE INFO. NO DISTANCE BTWN ACFT WAS GIVEN. THE OTHER ACFT WAS NOT BEING WORKED BY ATC AND NOT OBSERVED ON RADAR. NO TFC WAS ISSUED. HE SAID HIS ACFT WAS AN SMT.

Data retrieved from NASA's ASRS site as of August 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.