Air carrier X had less than standard separation from air carrier Y. System error.

Attributes
ACN	186139
Time
Date	199108
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : mcw
State Reference	IA
Altitude	msl bound lower : 32000 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 210 flight time total : 7000
ASRS Report	186139
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation non adherence : published procedure
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	faa : investigated
Miss Distance	horizontal : 12000 vertical : 1000
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Intra Facility Coordination Failure Operational Error

Narrative:

Air carrier X had previously been cleared to cross 80 mi east of mason city, ia, at FL290, pilot's discretion. Out altitude prior to descent was FL330. Shortly thereafter we call departing FL330. At approximately 66 mi east of mason city, and during the descent, the controller instructed us to level off at FL320. Because we were already below this altitude, I began to level off and initiate a climb back up in order to comply with the latest controller's instruction. The controller advised us of air carrier Y at FL310, at 1 O'clock. Neither myself nor the first officer saw any traffic. Shortly thereafter we were again cleared to FL290. Before leaving the frequency (132.72), I advised the controller that we were following our previously issued altitude clearance instructions, and asked if there was a problem. Controller said the problem was between ATC sectors and 'really doesn't affect you'.

Original NASA ASRS Text

Title: ACR X HAD LTSS FROM ACR Y. SYS ERROR.

Narrative: ACR X HAD PREVIOUSLY BEEN CLRED TO CROSS 80 MI E OF MASON CITY, IA, AT FL290, PLT'S DISCRETION. OUT ALT PRIOR TO DSCNT WAS FL330. SHORTLY THEREAFTER WE CALL DEPARTING FL330. AT APPROX 66 MI E OF MASON CITY, AND DURING THE DSCNT, THE CTLR INSTRUCTED US TO LEVEL OFF AT FL320. BECAUSE WE WERE ALREADY BELOW THIS ALT, I BEGAN TO LEVEL OFF AND INITIATE A CLB BACK UP IN ORDER TO COMPLY WITH THE LATEST CTLR'S INSTRUCTION. THE CTLR ADVISED US OF ACR Y AT FL310, AT 1 O'CLOCK. NEITHER MYSELF NOR THE FO SAW ANY TFC. SHORTLY THEREAFTER WE WERE AGAIN CLRED TO FL290. BEFORE LEAVING THE FREQ (132.72), I ADVISED THE CTLR THAT WE WERE FOLLOWING OUR PREVIOUSLY ISSUED ALT CLRNC INSTRUCTIONS, AND ASKED IF THERE WAS A PROBLEM. CTLR SAID THE PROBLEM WAS BTWN ATC SECTORS AND 'REALLY DOESN'T AFFECT YOU'.

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.