<< >> NASA ASRS Report 633859, October 2004

ZOB controller experienced operational error at FL310 when pilot's discretion descent clearance information was not coordination.

Attributes
ACN	633859
Time
Date	200410
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : djb.vortac
State Reference	OH
Altitude	msl single value : 31000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob.artcc tower : ind.tower
Operator	common carrier : air carrier
Make Model Name	A319
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zob.artcc
Operator	common carrier : air carrier
Make Model Name	Regional Jet CL65, Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 22 controller time certified in position1 : 22
ASRS Report	633859
Person 2
Affiliation	government : faa
Function	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Consequence	faa : investigated
Miss Distance	horizontal : 21000 vertical : 900
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Intra Facility Coordination Failure Operational Error

Narrative:

It was XA00. I had just taken over the position. I was told the A319 was descending into pit. The data block showed FL309 with an assigned altitude of FL290. The other traffic CRJ1 was converging at FL310, but still more than 4 mins out, so at normal descent rates should not have been a factor. I was not talking to the A319 at this point and later learned after the incident that the A319 clearance was changed to pilot's discretion from FL310 to FL290 which caused it to become a factor with the CRJ1 level at FL310. FL310 is the base altitude in the sector I was controling and the sector that gave the discretion descent controled FL290 and below. Had I known that the A319 was not descending, I would have devoted more attention to the situation.

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Original NASA ASRS Text

Title: ZOB CTLR EXPERIENCED OPERROR AT FL310 WHEN PLT'S DISCRETION DSCNT CLRNC INFO WAS NOT COORD.

Narrative: IT WAS XA00. I HAD JUST TAKEN OVER THE POS. I WAS TOLD THE A319 WAS DSNDING INTO PIT. THE DATA BLOCK SHOWED FL309 WITH AN ASSIGNED ALT OF FL290. THE OTHER TFC CRJ1 WAS CONVERGING AT FL310, BUT STILL MORE THAN 4 MINS OUT, SO AT NORMAL DSCNT RATES SHOULD NOT HAVE BEEN A FACTOR. I WAS NOT TALKING TO THE A319 AT THIS POINT AND LATER LEARNED AFTER THE INCIDENT THAT THE A319 CLRNC WAS CHANGED TO PLT'S DISCRETION FROM FL310 TO FL290 WHICH CAUSED IT TO BECOME A FACTOR WITH THE CRJ1 LEVEL AT FL310. FL310 IS THE BASE ALT IN THE SECTOR I WAS CTLING AND THE SECTOR THAT GAVE THE DISCRETION DSCNT CTLED FL290 AND BELOW. HAD I KNOWN THAT THE A319 WAS NOT DSNDING, I WOULD HAVE DEVOTED MORE ATTN TO THE SIT.

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.