Radar separation was lost between 2 small transport's while being vectored onto final approach.

Attributes
ACN	105206
Time
Date	198902
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : lan
State Reference	MI
Altitude	msl bound lower : 2500 msl bound upper : 2500
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : lan
Operator	general aviation : corporate
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
Flight Phase	descent : approach descent other
Route In Use	arrival other
Flight Plan	IFR
Aircraft 2
Operator	general aviation : corporate
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	descent : approach descent other
Route In Use	arrival other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
ASRS Report	105206
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	non adherence : required legal separation non adherence : published procedure
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Miss Distance	horizontal : 12000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I was working south arrival radar. I was working small transport X. He had been cleared for the ILS 10R approach and was joining the localizer from the south. The north arrival controller had small transport Y from the north and coordinated to follow my small transport X. The north controller asked me small transport X's airspeed since we had xa 42 radar that does not have airspeed readout. I, in turn, asked the small transport X pilot. At that point it became apparent that the sequence wouldn't work and sep was decreasing to less than minimum standards. The north controller then took evasive action and turned the small transport Y wbound, away from the small transport X.

Original NASA ASRS Text

Title: RADAR SEPARATION WAS LOST BETWEEN 2 SMT'S WHILE BEING VECTORED ONTO FINAL APCH.

Narrative: I WAS WORKING S ARR RADAR. I WAS WORKING SMT X. HE HAD BEEN CLRED FOR THE ILS 10R APCH AND WAS JOINING THE LOC FROM THE S. THE N ARR CTLR HAD SMT Y FROM THE N AND COORDINATED TO FOLLOW MY SMT X. THE N CTLR ASKED ME SMT X'S AIRSPD SINCE WE HAD XA 42 RADAR THAT DOES NOT HAVE AIRSPD READOUT. I, IN TURN, ASKED THE SMT X PLT. AT THAT POINT IT BECAME APPARENT THAT THE SEQUENCE WOULDN'T WORK AND SEP WAS DECREASING TO LESS THAN MINIMUM STANDARDS. THE N CTLR THEN TOOK EVASIVE ACTION AND TURNED THE SMT Y WBOUND, AWAY FROM THE SMT X.

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.