Controller had less than standard separation between air carrier X and Y. System error.

Attributes
ACN	120949
Time
Date	198908
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : alo
State Reference	IA
Altitude	msl bound lower : 11000 msl bound upper : 11000
Environment
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	descent other
Route In Use	enroute : direct enroute airway : zdc
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	descent other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
ASRS Report	120949
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 non adherence : required legal separation other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance
Consequence	faa : investigated
Miss Distance	horizontal : 18000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X reported at 120. Air carrier Y was cleared to 130. Air carrier X was cleared to 90 and asked to expedite descent. Air carrier Y was cleared to 110. Altitude reporting information was lost on both aircraft. Air carrier X was asked what his altitude was. He reported leaving 110. Air carrier Y was reclred to maintain 120. Air carrier Y had reported leaving 110 to 120.

Original NASA ASRS Text

Title: CTLR HAD LESS THAN STANDARD SEPARATION BETWEEN ACR X AND Y. SYSTEM ERROR.

Narrative: ACR X REPORTED AT 120. ACR Y WAS CLRED TO 130. ACR X WAS CLRED TO 90 AND ASKED TO EXPEDITE DESCENT. ACR Y WAS CLRED TO 110. ALT REPORTING INFO WAS LOST ON BOTH ACFT. ACR X WAS ASKED WHAT HIS ALT WAS. HE REPORTED LEAVING 110. ACR Y WAS RECLRED TO MAINTAIN 120. ACR Y HAD REPORTED LEAVING 110 TO 120.

Data retrieved from NASA's ASRS site as of August 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.