ZDC controller experienced loss of separation in holding pattern.

Attributes
ACN	583093
Time
Date	200305
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : acy.airport
State Reference	NJ
Altitude	msl bound lower : 8000 msl bound upper : 9000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc.artcc
Operator	common carrier : air carrier
Make Model Name	A330
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude descent : holding descent : approach
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zdc.artcc
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 9 controller time certified in position1 : 1 controller time certified in position2 : 11
ASRS Report	583093
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne less severe non adherence : clearance non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance
Consequence	faa : investigated
Miss Distance	horizontal : 12000 vertical : 500
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Aircraft #1 originally cleared to 8000 ft. Then given holding instructions, altitude changed to 9000 ft and read back correctly. Aircraft #2 subsequently climbed to 8000 ft. Traffic called and saw each other. Aircraft #1 descended through assigned altitude, received TCASII alert and climbed back up.

Original NASA ASRS Text

Title: ZDC CTLR EXPERIENCED LOSS OF SEPARATION IN HOLDING PATTERN.

Narrative: ACFT #1 ORIGINALLY CLRED TO 8000 FT. THEN GIVEN HOLDING INSTRUCTIONS, ALT CHANGED TO 9000 FT AND READ BACK CORRECTLY. ACFT #2 SUBSEQUENTLY CLBED TO 8000 FT. TFC CALLED AND SAW EACH OTHER. ACFT #1 DSNDED THROUGH ASSIGNED ALT, RECEIVED TCASII ALERT AND CLBED BACK UP.

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.