Less than standard separation between two air carrier. Operational error.

Attributes
ACN	99965
Time
Date	198812
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : iow
State Reference	IA
Altitude	msl bound lower : 29000 msl bound upper : 30000
Environment
Light	Night
Aircraft 1
Controlling Facilities	artcc : zau
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other
Route In Use	enroute airway : j60
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 18
ASRS Report	99965
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	other other : unspecified atc
Resolutory Action	controller : issued new clearance none taken : unable other
Consequence	faa : investigated
Miss Distance	horizontal : 24600 vertical : 1000
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X was eastbound over iowa city at FL290. Air carrier Y was wbound over iowa city at FL280. Y requested FL310 due to chop at FL280. I informed Y FL310 unavailable due to an aircraft behind him who was faster. Y then requested FL350. I informed him FL350 was reported as continuous light to moderate chop. He re-requested FL350 and I climbed him to FL350. When conflict alert went off. I turned Y 40 degree right. My next clearance was going to be a 40 degree right turn to air carrier X but air carrier Y requested to know the reason for the 40 degree turn. When I got the frequency back I turned X 40 degree right. They passed about 4.1 mi instead of 5 mi horizontal and approximately 1000' instead of 2000' vertical.

Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION BETWEEN TWO ACR. OPERATIONAL ERROR.

Narrative: ACR X WAS EBND OVER IOWA CITY AT FL290. ACR Y WAS WBOUND OVER IOWA CITY AT FL280. Y REQUESTED FL310 DUE TO CHOP AT FL280. I INFORMED Y FL310 UNAVAILABLE DUE TO AN ACFT BEHIND HIM WHO WAS FASTER. Y THEN REQUESTED FL350. I INFORMED HIM FL350 WAS RPTED AS CONTINUOUS LIGHT TO MODERATE CHOP. HE RE-REQUESTED FL350 AND I CLBED HIM TO FL350. WHEN CONFLICT ALERT WENT OFF. I TURNED Y 40 DEG RIGHT. MY NEXT CLRNC WAS GOING TO BE A 40 DEG RIGHT TURN TO ACR X BUT ACR Y REQUESTED TO KNOW THE REASON FOR THE 40 DEG TURN. WHEN I GOT THE FREQ BACK I TURNED X 40 DEG RIGHT. THEY PASSED ABOUT 4.1 MI INSTEAD OF 5 MI HORIZ AND APPROX 1000' INSTEAD OF 2000' VERT.

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.