Mmac and less than standard separation between air carrier and VFR GA twin in TCA. Operational error...

Attributes
ACN	173694
Time
Date	199103
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : bwi
State Reference	MD
Altitude	msl bound lower : 5500 msl bound upper : 5800
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : bwi artcc : slc
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent : approach descent other
Route In Use	enroute : on vectors
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	VFR
Person 1
Affiliation	company : air carrier
Function	controller : approach
Qualification	controller : radar
Experience	controller military : 4 controller radar : 8
ASRS Report	173694
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	conflict : nmac non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	flight crew : took evasive action none taken : insufficient time
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 0 vertical : 300
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X was northeast of bwi southbound descending and as he checked on my frequency, I issued traffic. GA small transport Y, VFR nebnd at 5500, was not on my frequency. Air carrier X took evasive action and climbed 500' to miss aircraft Y. Callback conversation with reporter revealed the following information. Reporter was working the final position. Feeder controller had been working both air carrier X and small transport Y before making handoff and frequency change on air carrier X. Feeder controller had not exchanged traffic with the two aircraft and had failed to ensure sep. After landing the flight crew called TRACON and they reviewed the incident via telephone, but there was no formal near midair collision or operation error report filed.

Original NASA ASRS Text

Title: MMAC AND LESS THAN STANDARD SEPARATION BETWEEN ACR AND VFR GA TWIN IN TCA. OPERATIONAL ERROR.

Narrative: ACR X WAS NE OF BWI SBND DSNDING AND AS HE CHKED ON MY FREQ, I ISSUED TFC. GA SMT Y, VFR NEBND AT 5500, WAS NOT ON MY FREQ. ACR X TOOK EVASIVE ACTION AND CLBED 500' TO MISS ACFT Y. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. REPORTER WAS WORKING THE FINAL POS. FEEDER CTLR HAD BEEN WORKING BOTH ACR X AND SMT Y BEFORE MAKING HDOF AND FREQ CHANGE ON ACR X. FEEDER CTLR HAD NOT EXCHANGED TFC WITH THE TWO ACFT AND HAD FAILED TO ENSURE SEP. AFTER LNDG THE FLC CALLED TRACON AND THEY REVIEWED THE INCIDENT VIA TELEPHONE, BUT THERE WAS NO FORMAL NMAC OR OP ERROR RPT FILED.

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.