Tpa controller's application of visual separation results in TCASII event at approximately 10000 ft.

Attributes
ACN	608255
Time
Date	200402
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : tpa.airport
State Reference	FL
Altitude	msl single value : 10000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : tpa.tracon
Operator	common carrier : air carrier
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : tpa.tracon
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller radar : 22 controller time certified in position1 : 20
ASRS Report	608255
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne less severe non adherence : far
Independent Detector	atc equipment : conflict alert aircraft equipment : tcas other controllera
Resolutory Action	flight crew : took evasive action
Miss Distance	vertical : 150
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

Aircraft X, a B737-800 was northbound at 9000 ft. Aircraft Y (an A320) was wbound at 10000 ft. Both aircraft were advised of the other and both aircraft advised that they had each other in sight. Aircraft X was then instructed to maintain visual separation with the A320 and climb to 12000 ft. Aircraft Y was told that the B737-800 was maintaining visual separation in the climb to 12000 ft. Aircraft X climbed at a rate so as to pass 100-200 ft below the A320. The A320 got a TCASII alert climb and climbed.

Original NASA ASRS Text

Title: TPA CTLR'S APPLICATION OF VISUAL SEPARATION RESULTS IN TCASII EVENT AT APPROX 10000 FT.

Narrative: ACFT X, A B737-800 WAS NBOUND AT 9000 FT. ACFT Y (AN A320) WAS WBOUND AT 10000 FT. BOTH ACFT WERE ADVISED OF THE OTHER AND BOTH ACFT ADVISED THAT THEY HAD EACH OTHER IN SIGHT. ACFT X WAS THEN INSTRUCTED TO MAINTAIN VISUAL SEPARATION WITH THE A320 AND CLB TO 12000 FT. ACFT Y WAS TOLD THAT THE B737-800 WAS MAINTAINING VISUAL SEPARATION IN THE CLB TO 12000 FT. ACFT X CLBED AT A RATE SO AS TO PASS 100-200 FT BELOW THE A320. THE A320 GOT A TCASII ALERT CLB AND CLBED.

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.