B737 deviates from assigned altitude in ZDC airspace.

Attributes
ACN	422860
Time
Date	199812
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : mol
State Reference	VA
Altitude	msl bound lower : 34700 msl bound upper : 35000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-300
Navigation In Use	Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	other personnel other
Experience	flight time last 90 days : 40 flight time total : 17000 flight time type : 40
ASRS Report	422860
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	altitude deviation : excursion from assigned altitude other anomaly other
Independent Detector	other flight crewa
Consequence	Other
Supplementary
Air Traffic Incident	Pilot Deviation

Narrative:

After requesting FL310, FL310 was selected in MCP. Aircraft initiated descent prior to clearance. Aircraft descended 300 ft. Correction was initiated. Center did not get an altitude alert.

Original NASA ASRS Text

Title: B737 DEVIATES FROM ASSIGNED ALT IN ZDC AIRSPACE.

Narrative: AFTER REQUESTING FL310, FL310 WAS SELECTED IN MCP. ACFT INITIATED DSCNT PRIOR TO CLRNC. ACFT DSNDED 300 FT. CORRECTION WAS INITIATED. CTR DID NOT GET AN ALT ALERT.

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.