ZMA controller experienced operational error at 5000 ft after approving a direct route with one aircraft that did not provide enough lateral spacing with another aircraft.

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Attributes
ACN	684870
Time
Date	200601
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : fll.airport
Altitude	msl single value : 5000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zma.artcc
Operator	common carrier : air carrier
Make Model Name	Beech 1900
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zma.artcc
Operator	common carrier : air carrier
Make Model Name	Merlin IV A
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 15 controller time certified in position1 : 15
ASRS Report	684870
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	atc equipment : conflict alert other controllera
Resolutory Action	controller : issued alert controller : issued new clearance flight crew : took evasive action
Consequence	faa : investigated
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I was working on sector 41 from XA07Z to XB06Z. Around XA50Z; I issued air carrier X descend clearance to 4000 ft. Air carrier Y checked on my frequency shortly after that level at 5000 ft. Air carrier Y requested direct destination and after evaluating the situation I issued the clearance. Shortly after that; air carrier Y requested lower and I instructed the pilot to stand by; and immediately instructed air carrier X to expedite his descent to 4000 ft to maintain my separation. After that; my next transmission was to turn air carrier Y 30 degrees to the left to maintain lateral and allow for his descent into zbv. About 20 seconds after that; conflict alert went off and I re-evaluated the situation. I noticed that my separation was maintained and I issued xfer of communication to air carrier X and turned air carrier Y back to zbv.

Original NASA ASRS Text

Title: ZMA CTLR EXPERIENCED OPERROR AT 5000 FT AFTER APPROVING A DIRECT RTE WITH ONE ACFT THAT DID NOT PROVIDE ENOUGH LATERAL SPACING WITH ANOTHER ACFT.

Narrative: I WAS WORKING ON SECTOR 41 FROM XA07Z TO XB06Z. AROUND XA50Z; I ISSUED ACR X DSND CLRNC TO 4000 FT. ACR Y CHKED ON MY FREQ SHORTLY AFTER THAT LEVEL AT 5000 FT. ACR Y REQUESTED DIRECT DEST AND AFTER EVALUATING THE SITUATION I ISSUED THE CLRNC. SHORTLY AFTER THAT; ACR Y REQUESTED LOWER AND I INSTRUCTED THE PLT TO STAND BY; AND IMMEDIATELY INSTRUCTED ACR X TO EXPEDITE HIS DSCNT TO 4000 FT TO MAINTAIN MY SEPARATION. AFTER THAT; MY NEXT XMISSION WAS TO TURN ACR Y 30 DEGS TO THE L TO MAINTAIN LATERAL AND ALLOW FOR HIS DSCNT INTO ZBV. ABOUT 20 SECONDS AFTER THAT; CONFLICT ALERT WENT OFF AND I RE-EVALUATED THE SITUATION. I NOTICED THAT MY SEPARATION WAS MAINTAINED AND I ISSUED XFER OF COM TO ACR X AND TURNED ACR Y BACK TO ZBV.

Data retrieved from NASA's ASRS site as of January 2009 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.