Radar vectors to avoid other aircraft resulted in air carrier Y overtaking air carrier X.

Attributes
ACN	113794
Time
Date	198906
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : tol
State Reference	OH
Altitude	msl bound lower : 17000 msl bound upper : 17800
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
ASRS Report	113794
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	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	other
Consequence	faa : investigated
Miss Distance	horizontal : 25500 vertical : 800
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I was working and/or watching 8-10 aircraft. Some aircraft were deviating for WX. Air carrier X entered my sector on V275 at FL240. Air carrier Y was 4 mi behind him at FL200. Air carrier X was 60 KTS faster. I started air carrier X down to FL230. I descended air carrier Y to 17,000 and turned him to 340 degree. When I got some spacing between air carrier X and air carrier Y, I descended air carrier X to 20,000. I turned air carrier X to a 330 heading and descended him to 10,000. There was 8 mi between air carrier X and air carrier Y. Just to be sure, I expedited air carrier X's descent and turned him to 290 degree for about 15 seconds, then turned him back to 030 degree, once he was clear of the pointout. I failed to turn air carrier Y further left thinking I had enough room. Air carrier Y caught air carrier X on the back side.

Original NASA ASRS Text

Title: RADAR VECTORS TO AVOID OTHER ACFT RESULTED IN ACR Y OVERTAKING ACR X.

Narrative: I WAS WORKING AND/OR WATCHING 8-10 ACFT. SOME ACFT WERE DEVIATING FOR WX. ACR X ENTERED MY SECTOR ON V275 AT FL240. ACR Y WAS 4 MI BEHIND HIM AT FL200. ACR X WAS 60 KTS FASTER. I STARTED ACR X DOWN TO FL230. I DESCENDED ACR Y TO 17,000 AND TURNED HIM TO 340 DEG. WHEN I GOT SOME SPACING BETWEEN ACR X AND ACR Y, I DESCENDED ACR X TO 20,000. I TURNED ACR X TO A 330 HDG AND DESCENDED HIM TO 10,000. THERE WAS 8 MI BETWEEN ACR X AND ACR Y. JUST TO BE SURE, I EXPEDITED ACR X'S DSCNT AND TURNED HIM TO 290 DEG FOR ABOUT 15 SECONDS, THEN TURNED HIM BACK TO 030 DEG, ONCE HE WAS CLEAR OF THE POINTOUT. I FAILED TO TURN ACR Y FURTHER LEFT THINKING I HAD ENOUGH ROOM. ACR Y CAUGHT ACR X ON THE BACK SIDE.

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.