Reported loss of separation between 2 air carrier B737's on approach to las.

Attributes
ACN	399756
Time
Date	199804
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : las
State Reference	NV
Altitude	msl bound lower : 6100 msl bound upper : 6100
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : las tower : ind
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise other descent : approach
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	approach : visual
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	other personnel other
Qualification	controller : radar
ASRS Report	399756
Person 2
Affiliation	government : faa
Function	other personnel other
Qualification	controller : developmental
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	other other : unspecified
Resolutory Action	controller : issued new clearance other
Consequence	Other
Miss Distance	horizontal : 9000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I was providing OJT on the stadium sector at las TRACON. Air carrier a, a B737, was being vectored on base leg to runway 25L, descending to 5600 ft and became in conflict with air carrier B, a B737, on visual approach to runway 25R. I took over the position and instructed air carrier B to cancel approach clearance, maintain 6100 ft, and I issued traffic. Air carrier B did not report air carrier a in sight. I vectored air carrier B right to 050 degrees. Separation standard was lost between air carrier B and air carrier a before air carrier B was established in the right turn. Human performance: the sector was busy when we took over. I gave the trainee too much latitude in his decision to vector air carrier a in front of air carrier B. I should have vectored air carrier B initially before issuing traffic which may have ensured standard separation.

Original NASA ASRS Text

Title: RPTED LOSS OF SEPARATION BTWN 2 ACR B737'S ON APCH TO LAS.

Narrative: I WAS PROVIDING OJT ON THE STADIUM SECTOR AT LAS TRACON. ACR A, A B737, WAS BEING VECTORED ON BASE LEG TO RWY 25L, DSNDING TO 5600 FT AND BECAME IN CONFLICT WITH ACR B, A B737, ON VISUAL APCH TO RWY 25R. I TOOK OVER THE POS AND INSTRUCTED ACR B TO CANCEL APCH CLRNC, MAINTAIN 6100 FT, AND I ISSUED TFC. ACR B DID NOT RPT ACR A IN SIGHT. I VECTORED ACR B R TO 050 DEGS. SEPARATION STANDARD WAS LOST BTWN ACR B AND ACR A BEFORE ACR B WAS ESTABLISHED IN THE R TURN. HUMAN PERFORMANCE: THE SECTOR WAS BUSY WHEN WE TOOK OVER. I GAVE THE TRAINEE TOO MUCH LATITUDE IN HIS DECISION TO VECTOR ACR A IN FRONT OF ACR B. I SHOULD HAVE VECTORED ACR B INITIALLY BEFORE ISSUING TFC WHICH MAY HAVE ENSURED STANDARD SEPARATION.

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.