Air carrier was issued a descent through occupied altitude.

Attributes
ACN	121859
Time
Date	198909
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : oma
State Reference	NE
Altitude	msl bound lower : 35000 msl bound upper : 37000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zmp
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 3 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller non radar : 1 controller radar : 5
ASRS Report	121859
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
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance
Consequence	Other
Miss Distance	horizontal : 12000 vertical : 1500
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I took a handoff on air carrier X from ZMP sector 39. Air carrier X was at FL370.I made a handoff on air carrier Y at FL350 to sector 38 and transferred communications. Air carrier X needed descent to FL330 to meet a ZKC flow restriction. I descended air carrier X to FL330, mistakenly thinking air carrier Y was at FL310. I became aware of the situation and climbed air carrier X to FL370. The sector 38 controller turned air carrier Y to avoid also.

Original NASA ASRS Text

Title: ACR WAS ISSUED A DESCENT THROUGH OCCUPIED ALT.

Narrative: I TOOK A HDOF ON ACR X FROM ZMP SECTOR 39. ACR X WAS AT FL370.I MADE A HDOF ON ACR Y AT FL350 TO SECTOR 38 AND TRANSFERRED COMS. ACR X NEEDED DSCNT TO FL330 TO MEET A ZKC FLOW RESTRICTION. I DSNDED ACR X TO FL330, MISTAKENLY THINKING ACR Y WAS AT FL310. I BECAME AWARE OF THE SITUATION AND CLBED ACR X TO FL370. THE SECTOR 38 CTLR TURNED ACR Y TO AVOID ALSO.

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.