Air carrier X descent through air carrier Y climbing had less than standard separation. System error...

Attributes
ACN	272395
Time
Date	199405
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : obk
State Reference	IL
Altitude	msl bound lower : 15000 msl bound upper : 15000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B747 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	descent other
Route In Use	enroute : direct enroute airway : zau
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Fokker 100
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 2
ASRS Report	272395
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : developmental
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	faa : investigated
Miss Distance	horizontal : 27000 vertical : 200
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error Intra Facility Coordination Failure

Narrative:

I was training a developmental controller at the kubbs arrival sector at ZAU. Air carrier X was a B747 landing ord and air carrier Y was a FK10 landing ord. X was cleared to pivot (although at the time we thought he was cleared to pappi) to cross 15 mi northeast of pappi at 10000 ft and to maintain 320 KTS or greater. Y was off of grr cleared to pappi and cleared to cross 15 mi northeast of pappi at 10000 ft and to maintain 310 KTS or greater. X was 12 mi in front and would not have been a factor if he was direct pappi as we thought. Direct pivot, however, gave us too great an angle of convergence. We kept waiting for X to 'correct' his course to the north. When he did not we attempted to stop his descent above Y. He was descending at 4500 FPM and was already through the altitude of Y when he reported. X had already been turned 20 degrees right to try to maintain separation, but it was not enough. The problem was the misunderstanding of the intersection to which X was cleared and could have been avoided with more thorough coordination.

Original NASA ASRS Text

Title: ACR X DSCNT THROUGH ACR Y CLBING HAD LTSS. SYS ERROR.

Narrative: I WAS TRAINING A DEVELOPMENTAL CTLR AT THE KUBBS ARR SECTOR AT ZAU. ACR X WAS A B747 LNDG ORD AND ACR Y WAS A FK10 LNDG ORD. X WAS CLRED TO PIVOT (ALTHOUGH AT THE TIME WE THOUGHT HE WAS CLRED TO PAPPI) TO CROSS 15 MI NE OF PAPPI AT 10000 FT AND TO MAINTAIN 320 KTS OR GREATER. Y WAS OFF OF GRR CLRED TO PAPPI AND CLRED TO CROSS 15 MI NE OF PAPPI AT 10000 FT AND TO MAINTAIN 310 KTS OR GREATER. X WAS 12 MI IN FRONT AND WOULD NOT HAVE BEEN A FACTOR IF HE WAS DIRECT PAPPI AS WE THOUGHT. DIRECT PIVOT, HOWEVER, GAVE US TOO GREAT AN ANGLE OF CONVERGENCE. WE KEPT WAITING FOR X TO 'CORRECT' HIS COURSE TO THE N. WHEN HE DID NOT WE ATTEMPTED TO STOP HIS DSCNT ABOVE Y. HE WAS DSNDING AT 4500 FPM AND WAS ALREADY THROUGH THE ALT OF Y WHEN HE RPTED. X HAD ALREADY BEEN TURNED 20 DEGS R TO TRY TO MAINTAIN SEPARATION, BUT IT WAS NOT ENOUGH. THE PROB WAS THE MISUNDERSTANDING OF THE INTXN TO WHICH X WAS CLRED AND COULD HAVE BEEN AVOIDED WITH MORE THOROUGH COORD.

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.