While being vectored to the ILS final approach course, separation was lost between air carrier X and...

Attributes
ACN	110685
Time
Date	198905
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : iad
State Reference	VA
Altitude	msl bound lower : 1500 msl bound upper : 3000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : iad
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent other
Route In Use	arrival other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : non radar
Experience	controller radar : 5
ASRS Report	110685
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe 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 : 9000 vertical : 500
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Busy session IFR conditions. I was running ILS apches to 1R and 1L. The air carrier X was established on the 1R localizer and cleared for the approach. The air carrier Y was being vectored to 1L, sequenced on the air carrier X. I did not have the 2 mi stagger, so I took the air carrier Y across the 1L localizer (wbound) for a mi, then back to it again. The air carrier Y appeared to take a very wide turn and did not reduce his speed as I had expected. The situation was not going to work. I decided to break out the air carrier X and go ahead and clear the air carrier Y for the 1L approach. The air carrier X was vectored around to the east downwind for 1R again and brought in with minimal delay. It would have been difficult to resequence the air carrier Y with the volume of traffic inbound from the west at the time. Trying to vector for min separation is sometimes difficult. I should have seen the situation deteriorating sooner and done something about it.

Original NASA ASRS Text

Title: WHILE BEING VECTORED TO THE ILS FINAL APCH COURSE, SEPARATION WAS LOST BETWEEN ACR X AND ACR Y.

Narrative: BUSY SESSION IFR CONDITIONS. I WAS RUNNING ILS APCHES TO 1R AND 1L. THE ACR X WAS ESTABLISHED ON THE 1R LOC AND CLRED FOR THE APCH. THE ACR Y WAS BEING VECTORED TO 1L, SEQUENCED ON THE ACR X. I DID NOT HAVE THE 2 MI STAGGER, SO I TOOK THE ACR Y ACROSS THE 1L LOC (WBOUND) FOR A MI, THEN BACK TO IT AGAIN. THE ACR Y APPEARED TO TAKE A VERY WIDE TURN AND DID NOT REDUCE HIS SPEED AS I HAD EXPECTED. THE SITUATION WAS NOT GOING TO WORK. I DECIDED TO BREAK OUT THE ACR X AND GO AHEAD AND CLEAR THE ACR Y FOR THE 1L APCH. THE ACR X WAS VECTORED AROUND TO THE E DOWNWIND FOR 1R AGAIN AND BROUGHT IN WITH MINIMAL DELAY. IT WOULD HAVE BEEN DIFFICULT TO RESEQUENCE THE ACR Y WITH THE VOLUME OF TFC INBND FROM THE W AT THE TIME. TRYING TO VECTOR FOR MIN SEPARATION IS SOMETIMES DIFFICULT. I SHOULD HAVE SEEN THE SITUATION DETERIORATING SOONER AND DONE SOMETHING ABOUT IT.

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.

While being vectored to the ILS final approach course, separation was lost between air carrier X and air carrier Y.