Operational error less than standard separation when aircraft #2 descending to FL250 overtakes and conflicts with aircraft #1 descending at a slower rate to FL240. TCASII RA evasive action taken by aircraft #1.

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Attributes
ACN	375804
Time
Date	199707
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : jpu
State Reference	OH
Altitude	msl bound lower : 25000 msl bound upper : 25000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent other
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 other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller non radar : 15 controller radar : 14
ASRS Report	375804
Person 2
Affiliation	government : faa
Function	controller : flight data
Qualification	controller : radar
Experience	controller non radar : 3 controller radar : 9 flight time total : 120
ASRS Report	375377
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 6200 vertical : 300
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Crw traffic was very complex. All aircraft were deviating around WX. The tracker had been in place for about 1 hour and 40 mins. He was very busy just separating data blocks. We were just starting to have to issue rertes to dfw. Pit traffic was entering the crw sector without the pit rerte. Also, pit arrs were starting to deviate away from ape. I intended to descend aircraft #1 under aircraft #2, both going to pit. I got busy separating aircraft with sse portion of the crw sector. When I realized aircraft #1 was descending slowly, I tried to stop aircraft #2 (descending to FL250) on top of aircraft #1 (descending to FL240). Aircraft #1 advised responding to a TCASII resolution. Supplemental information from acn 375377: I was re-entering the correct routing on 3 different flts at the time of the incident. Therefore, I had no knowledge of the impending problem.

Original NASA ASRS Text

Title: OPERROR LTSS WHEN ACFT #2 DSNDING TO FL250 OVERTAKES AND CONFLICTS WITH ACFT #1 DSNDING AT A SLOWER RATE TO FL240. TCASII RA EVASIVE ACTION TAKEN BY ACFT #1.

Narrative: CRW TFC WAS VERY COMPLEX. ALL ACFT WERE DEVIATING AROUND WX. THE TRACKER HAD BEEN IN PLACE FOR ABOUT 1 HR AND 40 MINS. HE WAS VERY BUSY JUST SEPARATING DATA BLOCKS. WE WERE JUST STARTING TO HAVE TO ISSUE RERTES TO DFW. PIT TFC WAS ENTERING THE CRW SECTOR WITHOUT THE PIT RERTE. ALSO, PIT ARRS WERE STARTING TO DEVIATE AWAY FROM APE. I INTENDED TO DSND ACFT #1 UNDER ACFT #2, BOTH GOING TO PIT. I GOT BUSY SEPARATING ACFT WITH SSE PORTION OF THE CRW SECTOR. WHEN I REALIZED ACFT #1 WAS DSNDING SLOWLY, I TRIED TO STOP ACFT #2 (DSNDING TO FL250) ON TOP OF ACFT #1 (DSNDING TO FL240). ACFT #1 ADVISED RESPONDING TO A TCASII RESOLUTION. SUPPLEMENTAL INFO FROM ACN 375377: I WAS RE-ENTERING THE CORRECT ROUTING ON 3 DIFFERENT FLTS AT THE TIME OF THE INCIDENT. THEREFORE, I HAD NO KNOWLEDGE OF THE IMPENDING PROB.

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.