ZKC controller lost separation between 2 climbing aircraft.

Attributes
ACN	574281
Time
Date	200302
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : ict.vortac
State Reference	KS
Altitude	msl bound lower : 17000 msl bound upper : 18500
Environment
Flight Conditions	Marginal
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zkc.artcc tower : orf.tower
Operator	general aviation : personal
Make Model Name	Learjet 60
Operating Under FAR Part	Part 91
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zkc.artcc
Operator	general aviation : personal
Make Model Name	Citation V
Operating Under FAR Part	Part 91
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller non radar : 5 controller radar : 15 controller time certified in position1 : 11
ASRS Report	574281
Person 2
Affiliation	government : faa
Function	controller : supervisor oversight : supervisor
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	atc equipment : conflict alert other controllera
Resolutory Action	controller : issued alert
Miss Distance	horizontal : 24000 vertical : 1500
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Just relieved last controller 5 mins prior. Fairly busy sector (low altitude). Took handoff on both aircraft, climbed both aircraft to FL230 initially. Realized back aircraft was faster, so turned first aircraft 20 degrees right and back aircraft 10 degrees left. Stopped back aircraft at 17000 ft. At the time, FL180 was unusable for separation due to low altimeter setting (29.83). Conflict alert activated and back aircraft's mode C read 17400 ft. Front aircraft's mode C read FL180. I asked back aircraft to verify level at 17000 ft, he said affirmative. Front aircraft said leaving FL185. They were approximately 4 mi apart. The supervisor asked what happened. I told him the same thing as above. I had momentarily forgot about FL180 being unusable.

Original NASA ASRS Text

Title: ZKC CTLR LOST SEPARATION BTWN 2 CLBING ACFT.

Narrative: JUST RELIEVED LAST CTLR 5 MINS PRIOR. FAIRLY BUSY SECTOR (LOW ALT). TOOK HDOF ON BOTH ACFT, CLBED BOTH ACFT TO FL230 INITIALLY. REALIZED BACK ACFT WAS FASTER, SO TURNED FIRST ACFT 20 DEGS R AND BACK ACFT 10 DEGS L. STOPPED BACK ACFT AT 17000 FT. AT THE TIME, FL180 WAS UNUSABLE FOR SEPARATION DUE TO LOW ALTIMETER SETTING (29.83). CONFLICT ALERT ACTIVATED AND BACK ACFT'S MODE C READ 17400 FT. FRONT ACFT'S MODE C READ FL180. I ASKED BACK ACFT TO VERIFY LEVEL AT 17000 FT, HE SAID AFFIRMATIVE. FRONT ACFT SAID LEAVING FL185. THEY WERE APPROX 4 MI APART. THE SUPVR ASKED WHAT HAPPENED. I TOLD HIM THE SAME THING AS ABOVE. I HAD MOMENTARILY FORGOT ABOUT FL180 BEING UNUSABLE.

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.