An ARTCC radar controller issued the same altitude to 2 aircraft.

Attributes
ACN	319380
Time
Date	199510
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : mol
State Reference	VA
Altitude	msl bound lower : 26000 msl bound upper : 27000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc tower : lgb
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude cruise other
Route In Use	enroute other
Flight Plan	IFR
Aircraft 2
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	other : unknown
Flight Phase	cruise other
Route In Use	enroute 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 : 200 flight time total : 20000 flight time type : 6000
ASRS Report	319380
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : commercial pilot : instrument
Experience	flight time last 90 days : 150 flight time total : 5000 flight time type : 1200
ASRS Report	318845
Events
Anomaly	conflict : airborne less severe non adherence : published procedure other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance other
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 60000 vertical : 1000
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Deviation other

Narrative:

ATC cleared us to FL270 and thought he had cleared us to FL260. He realized his mistake and turned us 30 degrees left and descended the other aircraft to avoid any conflict. We were still able to maintain about 10 NM separation on TCASII. Supplemental information from acn 318845: he said he thought he had stopped us at FL260. Other aircraft passed approximately 10 mi from us 1000 ft below us (TCASII estimate).

Original NASA ASRS Text

Title: AN ARTCC RADAR CTLR ISSUED THE SAME ALT TO 2 ACFT.

Narrative: ATC CLRED US TO FL270 AND THOUGHT HE HAD CLRED US TO FL260. HE REALIZED HIS MISTAKE AND TURNED US 30 DEGS L AND DSNDED THE OTHER ACFT TO AVOID ANY CONFLICT. WE WERE STILL ABLE TO MAINTAIN ABOUT 10 NM SEPARATION ON TCASII. SUPPLEMENTAL INFO FROM ACN 318845: HE SAID HE THOUGHT HE HAD STOPPED US AT FL260. OTHER ACFT PASSED APPROX 10 MI FROM US 1000 FT BELOW US (TCASII ESTIMATE).

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.