Conflict alert activated due to data block track jump. Separation maintained.

Attributes
ACN	106074
Time
Date	198903
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : eug
State Reference	OR
Altitude	msl bound lower : 18000 msl bound upper : 18000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : pit
Operator	common carrier : air carrier
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
Flight Phase	cruise other
Route In Use	enroute airway : v23
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time total : 7000
ASRS Report	106074
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	other anomaly other
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	other
Consequence	faa : investigated faa : reviewed incident with flight crew
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

Approximately 30 mins after takeoff from evg en route to sea on V23 at FL180, on centerline with a left correction angle of approximately 20 degrees (heading 335 degrees on a 355 arwy), we were given a right turn of 10 degrees, quickly followed by another right turn to 030 degrees. After turning I inquired if the turns were for traffic and the reply was a very short 'yes' with no further explanation. A left turn back on course followed within a minute or so and the first officer and I thought no more of the incident until the next sector north gave me a phone # to call collect. On speaking to center supervisor I was informed that there had been a loss of sep incident which the controller attributed to our flight making a 'sharp left turn.' he then asked a lot of questions about our headings during the event. Not until I asked if this 'incident' was the reason for the vectors were we informed of any conflict or traffic. On the morning of the X I phoned center from home to determine the status of the 'incident' and was informed that viewing the radar tapes indicated a computer glitch called 'track jumping' had caused a false alarm on the snitch machine and I had no cause for further concern.

Original NASA ASRS Text

Title: CONFLICT ALERT ACTIVATED DUE TO DATA BLOCK TRACK JUMP. SEPARATION MAINTAINED.

Narrative: APPROX 30 MINS AFTER TKOF FROM EVG ENRTE TO SEA ON V23 AT FL180, ON CENTERLINE WITH A LEFT CORRECTION ANGLE OF APPROX 20 DEGS (HDG 335 DEGS ON A 355 ARWY), WE WERE GIVEN A RIGHT TURN OF 10 DEGS, QUICKLY FOLLOWED BY ANOTHER RIGHT TURN TO 030 DEGS. AFTER TURNING I INQUIRED IF THE TURNS WERE FOR TFC AND THE REPLY WAS A VERY SHORT 'YES' WITH NO FURTHER EXPLANATION. A LEFT TURN BACK ON COURSE FOLLOWED WITHIN A MINUTE OR SO AND THE F/O AND I THOUGHT NO MORE OF THE INCIDENT UNTIL THE NEXT SECTOR N GAVE ME A PHONE # TO CALL COLLECT. ON SPEAKING TO CENTER SUPVR I WAS INFORMED THAT THERE HAD BEEN A LOSS OF SEP INCIDENT WHICH THE CTLR ATTRIBUTED TO OUR FLT MAKING A 'SHARP LEFT TURN.' HE THEN ASKED A LOT OF QUESTIONS ABOUT OUR HDGS DURING THE EVENT. NOT UNTIL I ASKED IF THIS 'INCIDENT' WAS THE REASON FOR THE VECTORS WERE WE INFORMED OF ANY CONFLICT OR TFC. ON THE MORNING OF THE X I PHONED CENTER FROM HOME TO DETERMINE THE STATUS OF THE 'INCIDENT' AND WAS INFORMED THAT VIEWING THE RADAR TAPES INDICATED A COMPUTER GLITCH CALLED 'TRACK JUMPING' HAD CAUSED A FALSE ALARM ON THE SNITCH MACHINE AND I HAD NO CAUSE FOR FURTHER CONCERN.

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.