ARTCC controller at ZOB descended air carrier Y at FL390 to FL290 with air carrier X at FL350.

Attributes
ACN	454167
Time
Date	199911
Day	Tue
Local Time Of Day	0601 To 1200
Place
State Reference	MI
Altitude	msl single value : 35000
Environment
Weather Elements	Turbulence
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob.artcc tower : boi.tower
Operator	common carrier : air carrier
Make Model Name	DC-10 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zob.artcc
Operator	common carrier : air carrier
Make Model Name	A319
Operating Under FAR Part	Part 121
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller limited radar : 3 controller military : 3 controller radar : 26
ASRS Report	454167
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : published procedure
Independent Detector	atc equipment : conflict alert other controllera
Resolutory Action	none taken : detected after the fact
Miss Distance	horizontal : 24600 vertical : 1400
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier Y crossing over air carrier X. Air carrier Y at FL390. Air carrier X at FL350. Descended air carrier Y FL370. Air carrier X psb direct grb. Thought air carrier Y was clear descended to FL290. Air carrier X was faster. Causal factor: noisy backgnd, chop at all altitudes except FL240, and giving relief briefing. Also finishing ord push.

Original NASA ASRS Text

Title: ARTCC CTLR AT ZOB DSNDED ACR Y AT FL390 TO FL290 WITH ACR X AT FL350.

Narrative: ACR Y XING OVER ACR X. ACR Y AT FL390. ACR X AT FL350. DSNDED ACR Y FL370. ACR X PSB DIRECT GRB. THOUGHT ACR Y WAS CLR DSNDED TO FL290. ACR X WAS FASTER. CAUSAL FACTOR: NOISY BACKGND, CHOP AT ALL ALTS EXCEPT FL240, AND GIVING RELIEF BRIEFING. ALSO FINISHING ORD PUSH.

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.