Less than standard separation between two air carrier in holding pattern. Operational error.

Attributes
ACN	102491
Time
Date	198901
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : ffu
State Reference	UT
Altitude	msl bound lower : 22000 msl bound upper : 22000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zlc
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	descent other other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
ASRS Report	102491
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Resolutory Action	none taken : unable none taken : insufficient time
Consequence	faa : investigated
Miss Distance	horizontal : 15000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Cleared FL230, aircraft X, to descend through FL220, aircraft Y, in holding stack. Controller error believing descending aircraft to be lowest in the stack. Discovered by automatic-alert system. Failed to check with other controller.

Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION BETWEEN TWO ACR IN HOLDING PATTERN. OPERATIONAL ERROR.

Narrative: CLRED FL230, ACFT X, TO DSND THROUGH FL220, ACFT Y, IN HOLDING STACK. CTLR ERROR BELIEVING DSNDING ACFT TO BE LOWEST IN THE STACK. DISCOVERED BY AUTO-ALERT SYSTEM. FAILED TO CHK WITH OTHER CTLR.

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.