Operational error. Loss of standard separation between air carrier X and air carrier Y.

Attributes
ACN	281154
Time
Date	199408
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : mem
State Reference	TN
Altitude	msl bound lower : 3000 msl bound upper : 3000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : mem
Operator	common carrier : air carrier
Make Model Name	DC-9 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : approach descent other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	SF 340A
Operating Under FAR Part	Part 121
Flight Phase	descent : approach descent other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller radar : 12
ASRS Report	281154
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	non adherence : published procedure non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Miss Distance	horizontal : 18000
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I was vectoring for an ILS approach due to hazy conditions. Controller sitting beside me also vectoring for ILS approach to a parallel runway. I was supposed to be turning final at 3000 ft and the other controller at 4000 ft. He coordinated to turn final at 2000 ft, but the SF34 he was controling made an extremely slow descent and also failed to intercept the parallel runway localizer. Visual separation obtained, but probably at less than 3 mi separation. I should not have approved the other controller's request to descend out of 4000 ft. My aircraft (a DC9) would have been level at 3000 ft and the required ATC separation maintained, even though the SF34 crossed the localizer for both parallel runways. I would like to stress the importance of maintaining vertical separation, ie, 1000 ft, when turning final on both visual and ILS approachs to parallel runways.

Original NASA ASRS Text

Title: OPERROR. LOSS OF STANDARD SEPARATION BTWN ACR X AND ACR Y.

Narrative: I WAS VECTORING FOR AN ILS APCH DUE TO HAZY CONDITIONS. CTLR SITTING BESIDE ME ALSO VECTORING FOR ILS APCH TO A PARALLEL RWY. I WAS SUPPOSED TO BE TURNING FINAL AT 3000 FT AND THE OTHER CTLR AT 4000 FT. HE COORDINATED TO TURN FINAL AT 2000 FT, BUT THE SF34 HE WAS CTLING MADE AN EXTREMELY SLOW DSCNT AND ALSO FAILED TO INTERCEPT THE PARALLEL RWY LOC. VISUAL SEPARATION OBTAINED, BUT PROBABLY AT LESS THAN 3 MI SEPARATION. I SHOULD NOT HAVE APPROVED THE OTHER CTLR'S REQUEST TO DSND OUT OF 4000 FT. MY ACFT (A DC9) WOULD HAVE BEEN LEVEL AT 3000 FT AND THE REQUIRED ATC SEPARATION MAINTAINED, EVEN THOUGH THE SF34 CROSSED THE LOC FOR BOTH PARALLEL RWYS. I WOULD LIKE TO STRESS THE IMPORTANCE OF MAINTAINING VERT SEPARATION, IE, 1000 FT, WHEN TURNING FINAL ON BOTH VISUAL AND ILS APCHS TO PARALLEL RWYS.

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.