Less than standard separation between army helicopter and commuter flight. Operational error.

Attributes
ACN	94623
Time
Date	198809
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : azo
State Reference	MI
Altitude	msl bound lower : 5000 msl bound upper : 5000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : azo
Operator	common carrier : air carrier
Make Model Name	Helicopter
Flight Phase	cruise other
Flight Plan	IFR
Aircraft 2
Operator	other
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
Flight Phase	cruise other descent other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller military : 4 controller radar : 4 controller supervisory : 2
ASRS Report	94623
Person 2
Affiliation	government : military
Function	flight crew : captain oversight : pic
Qualification	pilot : military
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	faa : investigated
Miss Distance	horizontal : 6000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Military helicopter X was overflying azo airspace level at 5000'. Flight data indicated the aircraft had a transponder, but it was apparently not working. I took a primary radar handoff on the aircraft from the adjacent approach control. I was also vectoring another aircraft to land at azo and had descended the aircraft from 9000' to 6000, initially to miss the helicopter at 5000'. I later turned the second aircraft (commuter Y) northbound and descended him to 5000'. I could not continue the descent of aircraft Y because of traffic below him at 4000'. I failed to maintain adequate tracking of the primary target helicopter and allowed the 2 aircraft to pass within 1 mi of each other at the same altitude. The pilot of the helicopter saw the aircraft and brought it to my attention. I had not paid close enough attention to the helicopter's position and west/O his transponder working I did not have the benefit of computer tracking. If his transponder had been functional, I am certain this would not have happened.

Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION BETWEEN ARMY HELI AND COMMUTER FLT. OPERATIONAL ERROR.

Narrative: MIL HELI X WAS OVERFLYING AZO AIRSPACE LEVEL AT 5000'. FLT DATA INDICATED THE ACFT HAD A TRANSPONDER, BUT IT WAS APPARENTLY NOT WORKING. I TOOK A PRIMARY RADAR HDOF ON THE ACFT FROM THE ADJACENT APCH CTL. I WAS ALSO VECTORING ANOTHER ACFT TO LAND AT AZO AND HAD DSNDED THE ACFT FROM 9000' TO 6000, INITIALLY TO MISS THE HELI AT 5000'. I LATER TURNED THE SECOND ACFT (COMMUTER Y) NBOUND AND DSNDED HIM TO 5000'. I COULD NOT CONTINUE THE DSCNT OF ACFT Y BECAUSE OF TFC BELOW HIM AT 4000'. I FAILED TO MAINTAIN ADEQUATE TRACKING OF THE PRIMARY TARGET HELI AND ALLOWED THE 2 ACFT TO PASS WITHIN 1 MI OF EACH OTHER AT THE SAME ALT. THE PLT OF THE HELI SAW THE ACFT AND BROUGHT IT TO MY ATTN. I HAD NOT PAID CLOSE ENOUGH ATTN TO THE HELI'S POS AND W/O HIS TRANSPONDER WORKING I DID NOT HAVE THE BENEFIT OF COMPUTER TRACKING. IF HIS TRANSPONDER HAD BEEN FUNCTIONAL, I AM CERTAIN THIS WOULD NOT HAVE HAPPENED.

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.