ZDC controller issues incorrect altitude and en route carj conflicts with descending E145.

Attributes
ACN	503662
Time
Date	200103
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : mol.vor
State Reference	VA
Altitude	msl bound lower : 26500 msl bound upper : 27000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc.artcc
Operator	common carrier : air carrier
Make Model Name	Regional Jet CL65, Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise : level ground : maintenance
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zdc.artcc
Operator	common carrier : air carrier
Make Model Name	EMB ERJ 145 ER&LR
Operating Under FAR Part	Part 121
Flight Phase	cruise : enroute altitude change
Route In Use	arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 13 controller time certified in position1 : 1
ASRS Report	503662
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment : conflict alert other controllera
Resolutory Action	controller : issued new clearance
Consequence	faa : investigated
Miss Distance	horizontal : 22800 vertical : 500
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Carj at FL260, E145 at FL290. I vectored E145 right for descent around carj and thought I descended to FL270, but mistakenly cleared to FL240. When within 5 mi laterally, E145 altitude indicated FL268 and I asked if he was level FL270 -- no answer. I asked again. Pilot said he was cleared to FL240. Separation was already lost. Because I believed descent to FL270 was issued, it wasn't until his altitude showed lower than FL270 that the conflict alert activated and I was alerted to the situation. I assumed the pilot had deviated from his clearance. By the time conflict alert activated, separation was lost.

Original NASA ASRS Text

Title: ZDC CTLR ISSUES INCORRECT ALT AND ENRTE CARJ CONFLICTS WITH DSNDING E145.

Narrative: CARJ AT FL260, E145 AT FL290. I VECTORED E145 R FOR DSCNT AROUND CARJ AND THOUGHT I DSNDED TO FL270, BUT MISTAKENLY CLRED TO FL240. WHEN WITHIN 5 MI LATERALLY, E145 ALT INDICATED FL268 AND I ASKED IF HE WAS LEVEL FL270 -- NO ANSWER. I ASKED AGAIN. PLT SAID HE WAS CLRED TO FL240. SEPARATION WAS ALREADY LOST. BECAUSE I BELIEVED DSCNT TO FL270 WAS ISSUED, IT WASN'T UNTIL HIS ALT SHOWED LOWER THAN FL270 THAT THE CONFLICT ALERT ACTIVATED AND I WAS ALERTED TO THE SIT. I ASSUMED THE PLT HAD DEVIATED FROM HIS CLRNC. BY THE TIME CONFLICT ALERT ACTIVATED, SEPARATION WAS LOST.

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.