Center controller clears aircraft to descent. Notices conflict. Clearance back to previous altitude.

Attributes
ACN	135459
Time
Date	199001
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : far
State Reference	ND
Altitude	msl bound lower : 25000 msl bound upper : 27000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zmp
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : flight engineer pilot : instrument pilot : atp
Experience	flight time last 90 days : 240 flight time total : 8000 flight time type : 1000
ASRS Report	135459
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 other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error
Situations
ATC Facility	procedure or policy : unspecified

Narrative:

While in cruise at FL270, requested FL250 from ZMP because of turbulence. Request was granted and I acknowledged with our full call sign. At 26200' ZMP asked our altitude and I replied 'leaving 26.2 for 250.' center immediately issued clearance back to FL270. I looked off our right side and saw our company medium large transport traffic at FL250. He saw us also, and there was no need for evasive action by either aircraft. Before we got handed off to the next frequency, I asked the controller how many frequencys he was working. His reply was 'now I am working 3 or 4, but before our little incident I was working 6.'

Original NASA ASRS Text

Title: CENTER CTLR CLEARS ACFT TO DESCENT. NOTICES CONFLICT. CLRNC BACK TO PREVIOUS ALT.

Narrative: WHILE IN CRUISE AT FL270, REQUESTED FL250 FROM ZMP BECAUSE OF TURB. REQUEST WAS GRANTED AND I ACKNOWLEDGED WITH OUR FULL CALL SIGN. AT 26200' ZMP ASKED OUR ALT AND I REPLIED 'LEAVING 26.2 FOR 250.' CENTER IMMEDIATELY ISSUED CLRNC BACK TO FL270. I LOOKED OFF OUR RIGHT SIDE AND SAW OUR COMPANY MLG TFC AT FL250. HE SAW US ALSO, AND THERE WAS NO NEED FOR EVASIVE ACTION BY EITHER ACFT. BEFORE WE GOT HANDED OFF TO THE NEXT FREQ, I ASKED THE CTLR HOW MANY FREQS HE WAS WORKING. HIS REPLY WAS 'NOW I AM WORKING 3 OR 4, BUT BEFORE OUR LITTLE INCIDENT I WAS WORKING 6.'

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.