Less than standard separation between air carrier and another IFR aircraft. Operational error.

Attributes
ACN	96097
Time
Date	198810
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : air
State Reference	OH
Altitude	msl bound lower : 31000 msl bound upper : 32500
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : intermediate altitude descent other
Route In Use	enroute airway : j80
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 : 210 flight time total : 26500 flight time type : 737
ASRS Report	96097
Person 2
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance
Consequence	Other
Miss Distance	horizontal : 12000 vertical : 1500
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

While en route to empty intersection on a phl-ind leg, indy center gave me descent instructions to flight level 310 from 330. While the first officer commenced a gradual descent to 310 I queried center regarding another aircraft I had visually at 11 O'clock and approximately 2 mi who appeared to be at flight level 310 by stating 'indy center, I assume that we have radar sep by you with the traffic I have at 11 O'clock.' a brief silence ensued followed by instructions to return immediately to FL330. No further reference was made by center of the incident. This all occurred on frequency 132.82.

Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION BETWEEN ACR AND ANOTHER IFR ACFT. OPERATIONAL ERROR.

Narrative: WHILE ENRTE TO EMPTY INTXN ON A PHL-IND LEG, INDY CENTER GAVE ME DSCNT INSTRUCTIONS TO FLT LEVEL 310 FROM 330. WHILE THE F/O COMMENCED A GRADUAL DSCNT TO 310 I QUERIED CENTER REGARDING ANOTHER ACFT I HAD VISUALLY AT 11 O'CLOCK AND APPROX 2 MI WHO APPEARED TO BE AT FLT LEVEL 310 BY STATING 'INDY CENTER, I ASSUME THAT WE HAVE RADAR SEP BY YOU WITH THE TFC I HAVE AT 11 O'CLOCK.' A BRIEF SILENCE ENSUED FOLLOWED BY INSTRUCTIONS TO RETURN IMMEDIATELY TO FL330. NO FURTHER REFERENCE WAS MADE BY CENTER OF THE INCIDENT. THIS ALL OCCURRED ON FREQ 132.82.

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.