Air carrier X probably had less than standard separation from aircraft Y. Probable system error.

Attributes
ACN	141035
Time
Date	199003
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : olc
State Reference	NV
Altitude	msl bound lower : 33000 msl bound upper : 34000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zlc
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude cruise other
Route In Use	enroute : direct enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 6500 flight time type : 1100
ASRS Report	141035
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 250 flight time total : 6000 flight time type : 200
ASRS Report	141233
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	controller : issued new clearance other
Consequence	faa : investigated
Miss Distance	vertical : 1000
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

During cruise at FL330, ZLC told air carrier X left 30 degrees for traffic. The following exchange took place: us, 'roger, left 30 degrees'. ATC, 'climb to FL350'. Us, 'unable.' ATC, 'turn left 30 degrees and give me a climb to some altitude.' us, 'roger'. We turned and climbed to FL340 (maximum capable altitude) and were cleared back down to FL330 and back on course within 2 mins. No other aircraft seen. When asked for an explanation, ZLC said that aircraft Y was lost in the 'data blocks'. Controller said that the data blocks obscured aircraft Y and he did 'not see the guy coming up from the south'. We got the impression that this has happened before in this area. Supplemental information from acn 141233. In the way of explanation, ZLC volunteered that occasionally 'data blocks' are obscured by other 'data blocks' and that he did not see 'the guy coming up from the south'. We got the impression that the situation happens regularly in this specific area.

Original NASA ASRS Text

Title: ACR X PROBABLY HAD LESS THAN STANDARD SEPARATION FROM ACFT Y. PROBABLE SYSTEM ERROR.

Narrative: DURING CRUISE AT FL330, ZLC TOLD ACR X LEFT 30 DEGS FOR TFC. THE FOLLOWING EXCHANGE TOOK PLACE: US, 'ROGER, L 30 DEGS'. ATC, 'CLB TO FL350'. US, 'UNABLE.' ATC, 'TURN L 30 DEGS AND GIVE ME A CLB TO SOME ALT.' US, 'ROGER'. WE TURNED AND CLBED TO FL340 (MAX CAPABLE ALT) AND WERE CLRED BACK DOWN TO FL330 AND BACK ON COURSE WITHIN 2 MINS. NO OTHER ACFT SEEN. WHEN ASKED FOR AN EXPLANATION, ZLC SAID THAT ACFT Y WAS LOST IN THE 'DATA BLOCKS'. CTLR SAID THAT THE DATA BLOCKS OBSCURED ACFT Y AND HE DID 'NOT SEE THE GUY COMING UP FROM THE S'. WE GOT THE IMPRESSION THAT THIS HAS HAPPENED BEFORE IN THIS AREA. SUPPLEMENTAL INFO FROM ACN 141233. IN THE WAY OF EXPLANATION, ZLC VOLUNTEERED THAT OCCASIONALLY 'DATA BLOCKS' ARE OBSCURED BY OTHER 'DATA BLOCKS' AND THAT HE DID NOT SEE 'THE GUY COMING UP FROM THE S'. WE GOT THE IMPRESSION THAT THE SITUATION HAPPENS REGULARLY IN THIS SPECIFIC AREA.

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.