Separation was lost between aircraft on converging courses.

Attributes
ACN	124887
Time
Date	198910
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : per
State Reference	OK
Altitude	msl bound lower : 33000 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zkc tower : ord
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
ASRS Report	124887
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	non adherence : required legal separation non adherence : published procedure
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance
Consequence	Other
Miss Distance	horizontal : 29400 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X check on frequency at FL350 landing okc from northeast. Air carrier Y on frequency at FL330 per rzc (sebnd). With aircraft 2 mins apart, air carrier X requested lower altitude. Told he would have to wait or could take turns. He requested turn. Told to turn 10 degrees right and descend to FL240. C/a activated. Track on air carrier Y appeared to jump slightly. Aircraft now within 5 mi. Air carrier X reported air carrier Y in sight. Turned air carrier X 10 degrees right further and air carrier Y 15 degrees right. Lost sep for 1 sweep and then regained it. Wind was 120 KTS from the west. Even though the sep looked good, a slight target jump and the aircraft adjustment from the wind resulted in loss of sep. To prevent recurrence, separate by more than 5 mi and take into account the wind. Also air carrier Y changed radar sites which resulted in slight jumping of target.

Original NASA ASRS Text

Title: SEPARATION WAS LOST BETWEEN ACFT ON CONVERGING COURSES.

Narrative: ACR X CHK ON FREQ AT FL350 LNDG OKC FROM NE. ACR Y ON FREQ AT FL330 PER RZC (SEBND). WITH ACFT 2 MINS APART, ACR X REQUESTED LOWER ALT. TOLD HE WOULD HAVE TO WAIT OR COULD TAKE TURNS. HE REQUESTED TURN. TOLD TO TURN 10 DEGS RIGHT AND DSND TO FL240. C/A ACTIVATED. TRACK ON ACR Y APPEARED TO JUMP SLIGHTLY. ACFT NOW WITHIN 5 MI. ACR X RPTED ACR Y IN SIGHT. TURNED ACR X 10 DEGS RIGHT FURTHER AND ACR Y 15 DEGS RIGHT. LOST SEP FOR 1 SWEEP AND THEN REGAINED IT. WIND WAS 120 KTS FROM THE W. EVEN THOUGH THE SEP LOOKED GOOD, A SLIGHT TARGET JUMP AND THE ACFT ADJUSTMENT FROM THE WIND RESULTED IN LOSS OF SEP. TO PREVENT RECURRENCE, SEPARATE BY MORE THAN 5 MI AND TAKE INTO ACCOUNT THE WIND. ALSO ACR Y CHANGED RADAR SITES WHICH RESULTED IN SLIGHT JUMPING OF TARGET.

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.