Air carrier X same altitude assigned air carrier Y had less than standard separation. System error.

Attributes
ACN	204730
Time
Date	199203
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : rex
State Reference	FO
Altitude	msl bound lower : 35000 msl bound upper : 35000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : mmty
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : flight engineer pilot : instrument pilot : atp
Experience	flight time last 90 days : 220 flight time total : 17000 flight time type : 6000
ASRS Report	204730
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : cfi pilot : flight engineer
Experience	flight time last 90 days : 210 flight time total : 5900 flight time type : 1900
ASRS Report	204608
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation non adherence : published procedure
Independent Detector	other flight crewa
Resolutory Action	none taken : insufficient time
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 1500 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X cruise at FL350, flight engineer called traffic at 12 O'clock. An air carrier Y passed approximately 1500 ft off our nose at same altitude. No deviation was necessary. Monterey center, when asked, had no explanation. Air carrier Y was not aware, nor saw us. TCASII would have alerted us much earlier and probably issued an RA.

Original NASA ASRS Text

Title: ACR X SAME ALT ASSIGNED ACR Y HAD LTSS. SYSTEM ERROR.

Narrative: ACR X CRUISE AT FL350, FLT ENGINEER CALLED TFC AT 12 O'CLOCK. AN ACR Y PASSED APPROX 1500 FT OFF OUR NOSE AT SAME ALT. NO DEV WAS NECESSARY. MONTEREY CTR, WHEN ASKED, HAD NO EXPLANATION. ACR Y WAS NOT AWARE, NOR SAW US. TCASII WOULD HAVE ALERTED US MUCH EARLIER AND PROBABLY ISSUED AN RA.

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.