Descending aircraft overtook a preceding aircraft which resulted in less than standard separation.

Attributes
ACN	149003
Time
Date	199006
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : lan
State Reference	MI
Altitude	msl bound lower : 31000 msl bound upper : 31000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : non radar
Qualification	controller : non radar
Experience	controller non radar : 1
ASRS Report	149003
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment other atc equipment : unspecified
Resolutory Action	controller : issued new clearance other
Consequence	faa : investigated
Miss Distance	horizontal : 27000 vertical : 600
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Better communications, req congestion, the action taken was appropriate. Callback conversation with reporter revealed the following information. Reporter stated that he was busy on the manual side and he could not provide any more detail than what he submitted. An operational error was reported. Equipment detected error. Controller took some action to separate aircraft. Both aircraft were air carrier. Maybe medium large transport type. Aircraft were same direction at different altitudes. One act asked for descent clearance. Controller issued clearance and aircraft overtook the preceding aircraft.

Original NASA ASRS Text

Title: DESCENDING ACFT OVERTOOK A PRECEDING ACFT WHICH RESULTED IN LESS THAN STANDARD SEPARATION.

Narrative: BETTER COMS, REQ CONGESTION, THE ACTION TAKEN WAS APPROPRIATE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. RPTR STATED THAT HE WAS BUSY ON THE MANUAL SIDE AND HE COULD NOT PROVIDE ANY MORE DETAIL THAN WHAT HE SUBMITTED. AN OPERROR WAS RPTED. EQUIP DETECTED ERROR. CTLR TOOK SOME ACTION TO SEPARATE ACFT. BOTH ACFT WERE AIR CARRIER. MAYBE MLG TYPE. ACFT WERE SAME DIRECTION AT DIFFERENT ALTS. ONE ACT ASKED FOR DSNT CLRNC. CTLR ISSUED CLRNC AND ACFT OVERTOOK THE PRECEDING ACFT.

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.