B727 and lear jet had less than legal separation in D-21 class B.

Attributes
ACN	484370
Time
Date	200008
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : dtw.airport
State Reference	MI
Altitude	msl single value : 5000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : d21.tracon tower : dtw.tower
Operator	general aviation : corporate
Make Model Name	Gates Learjet Corp Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Navigation In Use	other vortac
Flight Phase	climbout : vacating altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : d21.tracon
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	climbout : vacating altitude
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : departure
Qualification	controller : radar
Person 2
Affiliation	government : faa
Function	controller : departure oversight : supervisor
Qualification	controller : radar
Events
Anomaly	non adherence : required legal separation non adherence : published procedure non adherence : far other anomaly other
Independent Detector	atc equipment : conflict alert other controllera
Resolutory Action	controller : issued new clearance other
Miss Distance	horizontal : 12000
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Inter Facility Coordination Failure Operational Error

Narrative:

I was working moderate departure traffic wbound out of dtw. Air carrier Y to dallas checked in followed shortly by aircraft X going to sturgis, mi. Both aircraft were climbing to 10000 ft MSL and assigned the same heading and both were off runway 3C. The learjet aircraft X was on the wrong transponder code and I gave him the correct code. When he automatic-acquired, he was 2 mi behind air carrier Y at the same altitude. I stopped air carrier Y climb and expedited the lear. I notified my supervisor of a possible system error. I was told that since the lear wasn't tagged up until there was positive separation that an occurrence had not occurred. This error would not have happened if the local controller was aware that a light lear jet will outperform a B727 going all the way to dallas (fully loaded).

Original NASA ASRS Text

Title: B727 AND LEAR JET HAD LESS THAN LEGAL SEPARATION IN D-21 CLASS B.

Narrative: I WAS WORKING MODERATE DEP TFC WBOUND OUT OF DTW. ACR Y TO DALLAS CHKED IN FOLLOWED SHORTLY BY ACFT X GOING TO STURGIS, MI. BOTH ACFT WERE CLBING TO 10000 FT MSL AND ASSIGNED THE SAME HEADING AND BOTH WERE OFF RWY 3C. THE LEARJET ACFT X WAS ON THE WRONG XPONDER CODE AND I GAVE HIM THE CORRECT CODE. WHEN HE AUTO-ACQUIRED, HE WAS 2 MI BEHIND ACR Y AT THE SAME ALT. I STOPPED ACR Y CLB AND EXPEDITED THE LEAR. I NOTIFIED MY SUPVR OF A POSSIBLE SYS ERROR. I WAS TOLD THAT SINCE THE LEAR WASN'T TAGGED UP UNTIL THERE WAS POSITIVE SEPARATION THAT AN OCCURRENCE HAD NOT OCCURRED. THIS ERROR WOULD NOT HAVE HAPPENED IF THE LCL CTLR WAS AWARE THAT A LIGHT LEAR JET WILL OUTPERFORM A B727 GOING ALL THE WAY TO DALLAS (FULLY LOADED).

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.