Air carrier X had less than standard separation from air carrier Y. System error.

Attributes
ACN	194126
Time
Date	199111
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : sba
State Reference	CA
Altitude	msl bound lower : 10000 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : oak
Operator	common carrier : air carrier
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Flight Phase	cruise other
Route In Use	enroute : direct enroute airway : zla
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 : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar controller : developmental
Experience	controller non radar : 3
ASRS Report	194126
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
Resolutory Action	controller : issued new clearance other
Consequence	faa : investigated
Miss Distance	horizontal : 27000 vertical : 700
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X level flight 10000. Air carrier Y, in a descent, in front of air carrier X, slowed his airspeed in preparation for approach to sba, causing air carrier X to overtake air carrier Y, causing loss of separation. Discovered by operational error detection program. Corrective action: issued vector to maintain 5 mi lateral.

Original NASA ASRS Text

Title: ACR X HAD LTSS FROM ACR Y. SYS ERROR.

Narrative: ACR X LEVEL FLT 10000. ACR Y, IN A DSCNT, IN FRONT OF ACR X, SLOWED HIS AIRSPD IN PREPARATION FOR APCH TO SBA, CAUSING ACR X TO OVERTAKE ACR Y, CAUSING LOSS OF SEPARATION. DISCOVERED BY OPERROR DETECTION PROGRAM. CORRECTIVE ACTION: ISSUED VECTOR TO MAINTAIN 5 MI LATERAL.

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.